An introduction to marine drilling

THE AUTHOR Malcolm Maclachlan was born in Dover, England in 1947 and first worked at sea at the age of fourteen when he gained employment illegally on a crosschannel ferry through a 'misunderstanding' with the ship's master After training for three years on the cadet ship HMS 'Worcester' he sailed as midshipman with the Blue Funnel Line and gained his second mate's certificate at the age of 20 He served as a navigating officer with several deep sea and coastal shipping companies, and after qualifying as a Master Mariner held command of seven containerships whilst still in his early thirties He spent a year lecturing in navigation and seamanship at Leith Nautical College before joining the British drilling contractor Houlder Offshore Limited as a control room operator/mate He served on the semi-submersible drilling rigs 'High Seas Driller' and 'Kingsnorth UK' in the North Sea and aboard the dynamically-positioned diving support vessel 'Orelia' in the Persian Gulf war zone He has been writing and cartooning for many years and became a full-time marine writer and illustrator in 1986, when he was a casualty of the widespread cut-backs in the drilling industry caused by the slumping oil price He has contributed many articles, short stories and drawings to various marine journals and is currently writing a novel set on a North Sea rig Married with a young family, he lives in Biggar, Scotland CONTENTS FOREWORD PREFACE ACKNOWLEDGEMENTS Chapter 1: The Development of Marine Rotary Drilling Hand-dug wells Spring pole drilling Cable tool drilling Rotary drilling Marine drilling 11 11 11 13 18 20 Chapter 2: Preparations for an Offshore Drilling Operation The parties involved The well owner The operator The drilling contractor The drilling contract Supply and service companies Government departments The costs of drilling offshore Well types Petroleum geology The formation of hydrocarbons Migration of hydrocarbons Reservoirs Anticlines Fault traps Stratigraphic traps Unconformity traps Exploration methods Offshore surveying techniques Magnetic surveys Gravimetric surveys Seismic surveys Drilling rig site surveys 25 25 27 27 28 30 31 35 36 42 45 46 46 47 47 47 49 49 49 53 53 53 53 55 Chapter 3: Offshore Drilling Platform Types Fixed drilling platforms Fixed platforms with floating drilling tenders Self-contained fixed platforms Mobile drilling rigs Submersibles Self-elevating (jack-up) platforms Semi-submersibles Drill ships Barge rigs Chapter 4: The Offshore Rig and its Equipment Basic rig components The drill floor The derrick The drawworks The blocks, hook & drilling line The swivel, kelly & rotary hose The rotary table , , The drilling fluid circulation system Drill string motion compensation Downhole bumper subs Surface drill string motion compensators The power plant Drilling equipment API specifications Drilling bits Drill pipe Drill collars Stabilizers & reamers The drill string & bottom hole assembly Tubular handling tools Other drilling tools Sub-sea equipment The temporary guide base The permanent guide base The wellhead/casing hanger system Well control & the blow-out preventer stack The marine riser The riser tensioning system d 57 57 59 59 61 63 64 71 81 85 89 89 89 90 92 94 96 99 102 112 113 114 120 123 123 123 130 134 136 139 139 143 145 145 146 146 148 157 162 165 Chapter 5: Drilling Operations Running in the hole 166 Drilling ahead 171 Making a connection 172 Tripping 177 Running & cementing casing 180 Directional drilling 183 Drilling hazards 189 Stuck pipe 189 Fishing 190 Lost circulation 193 Kicks & blow-outs 194 Hydrogen sulphide 200 Weather & ice 200 Drilling operational sequence 202 Moving rig onto location & running anchors 203 Rigging up 203 Running the temporary guide base 204 Spudding in & drilling 36" hole 205 Running 30" casing & landing the permanent guide base 205 Cementing the 30" casing 207 Drilling 26" hole 209 Running & cementing 20" casing & running the 18314" wellhead 210 Running the 183/4" BOP stack & the marine riser 210 Drilling 17112" hole 213 Logging 215 Running & cementing 13%" casing 215 Making a gyro survey 218 Drilling 12114" hole 219 Logging 219 Running & cementing 9518" casing 219 Displacing the hole to oil base mud 219 Drilling 8112" hole to total depth 219 Coring 220 Logging 220 Running & cementing the 7" liner 222 Well testing 222 Well stimulation 225 FOREWORD Plugging & suspending or abandoning the well Contingencies & weather 227 227 Chapter 6: Marine Operations 228 Basic rig stability 228 Displacement & the principle of flotation 228 The centre of gravity 230 The centre of buoyancy 230 Reserve buoyancy 230 The effect on the CG of adding, removing or shifting weights 230 The righting lever 230 The metacentre 234 Ballasting & free surfaces 234 Ballasting conditions 236 Rig structure & safety maintenance 237 Lifesaving & firefighting equipment 238 Work permits 239 Standby boats 240 Rig-moves 242 Navigation and pilotage 243 Towage 244 Approaching the location 245 Running anchors 247 Anchor types 250 Anchor patterns 251 Pre-tensioning 252 The moorings during drilling 253 Pulling anchors , 253 Dynamic positioning systems 255 Rig supplies 259 Helicopter operations 263 Chapter 7: Rig Personnel & Training Semi-submersible rig personnel Jack-up rig & drill ship personnel Rig personnel training 265 265 279 280 GLOSSARY OF MARINE DRILLING TERMS 284 Over the years, I have seen many changes in the industry from the period of growth in the 1970's to our present day recession, I have had the privilege to witness first hand some outstanding advances in techniques and technology and yet for me at least, drilling remains something of a mystery Infamous for its jargon, it is as complex as it is fascinating It is therefore a particular pleasure to discover, after so many years, a book which is both readable and comprehensive, and which succeeds in revealing to me, as I am sure it will for all its readers, whatever their level of interest, something of the 'black art' of drilling It also gives me pleasure to think that much of the authors knowledge arises from his connection with Houlders First as a cadet on the "Worcester" established at Ingress Abbey on the Thames, my Grandfathers home and more recently during his time offshore with the company Houlder Marine Drilling is the offspring of the shipping company founded by my Grandfather in 1848 Interest in drilling arose in about 1973 as the result of a chance conversation with a Norwegian shipowner who introduced me to Bernard Larsen, another shipowner, who I believe to have originated the conceptual design for the famous H-3 which is illustrated on page 29 Just as the author learned from Houlder, so Houlder in turn had learned from the established drilling industry which in turn had learned from the Moho project This was to discover by drilling, the composition of the core of the earth As much as possible was to be drilled through water, and I think that the drillship owes more to the Moho technology than to the offshore shallows of Louisiana Houlder in turn claims to have originated the idea of transporting a semi-submersible drilling rig on the deck of another ship Page 39 shows the High Seas Driller being carried by this method I conceived the idea and made the preliminary calculations while waiting in the Boardroom of the China National Oil Company in Beiching! I think overall that Houlder has traditionally prospered by innovation and of the innovative approach used for the layout and content of this book is anything to go by, it should be an outstanding success PREFACE This book was conceived during the author's own quest offshore for the answers to a multitude of questions - questions that are inevitably asked by any curious 'green hand' or 'boll weevil' in his first wondrous weeks aboard a semi-submersible or jack-up rig In a complex engineering environment such as an offshore drilling rig only so much can be deduced from a silent observation of the strange and mysterious procedures, and invariably one must repeatedly seek explanations It is not always easy, however, or diplomatic, to ask a driller to explain the intricacies of his art when he is attempting to make a speedy 'round trip' under pressure from a cost-conscious 'company man' Nor is a weary roughneck or derrickman likely to want to spend an extra half hour in the messroom after his 'tour' describing the arduous work he has just been doing for a whole half day The drilling jig-saw puzzle can therefore take a considerable time to piece together, and in retrospect I wish now that I had had the benefit of a book on marine drilling to guide me through my first tentative trip offshore ACKNOWLEDGEMENTS Thanks are due to Adrian Rose, safety officer, and Ian Edwards, barge operator, both of Houlder Offshore, for their helpful clarifications; to Jim Langley of Brown Brothers for information about motion compensators, and to Gavin Strachan, marketing manager of Atlantic Drilling, for his lucid explanation of drilling contracts I must also acknowledge the generosity of Phillips Petroleum and BP, who provided many illustrations, and the many companies who sent me research material Special thanks must also go to my wife Lesley for her encouragement and countless cups of coffee, and to David Gallimore of Dayton's Publishing who had the courage to back my idea form beginning to end The simple aim of this book, then, is to explain to the new rig hand, to the offshore job applicant, to those on the periphery of the offshore industry who may never have the chance to go out to a rig and see for themselves, and to the interested layman and student on the 'beach' the main operations of this fascinating industry It does not pretend to be a comprehensive or learned study of the oil exploration business, nor does it masquerade as an instructional manual of drilling technology; it is hoped merely to throw a little truthful light on some of the operations of an industry which all too often is portrayed by the mass media as being simply a matter of grim and grimy men heaving and slithering on a wet deck as they struggle to latch massive wrenches onto a steel pipe That is one interesting facet of marine drilling, but there are many more which are rarely seen by those not fortunate enough to witness the workings of an offshore rig For any technical errors or omissions I can only apologise to the marine drilling fraternity and ask for their forbearance Biggar, Scotland March 1987 CHAPTER 1: THE DEVELOPMENT OF MARINE ROTARY DRILLING Since his earliest days, man has dug holes in the earth's crust in his search for water, salt and other minerals Over the centuries his digging techniques have changed and become more efficient, culminating in the method today known as rotary drilling which is almost universally used in oil and gas exploration, both on land and offshore Rotary drilling with a land rig is a complex business On an offshore rig it is even more involved, and at the same time is made hazardous by the hostile elements An appreciation of the innovative way in which oilmen have overcome their difficulties can be gained by looking first at the earlier, simpler drilling methods which led to the development of rotary drilling HAND DUG WELLS The age-old traditional method of digging a water well by hand was for one man to pound a hole in the ground with a sharp implement like a big chisel As the hole got deeper and the cuttings started accumulating at the bottom of the hole, the digger had to load them into some sort of container which an assistant at the top of the hole then pulled out Digging had to be temporarily halted for this to be done and the well-digging operation was slow and tedious The walls of the hole had a tendency to cave in as it got deeper, so to prevent this the well had to be lined with some material such as wood or brick as it progressed downwards These materials were the forerunners of what is now known as casing SPRING POLE DRILLING Hand-digging was slow and dangerous for the digger, especially as he dug through a hydrocarbon-bearing zone and oil or gas started seeping into the hole A safer and more efficient mechanical method of digging was sought and, according to ancient Chinese manuscripts, one was in use in China as early as the 3rd Century AD These manuscripts described a method which was really only a logical development from hand-digging The Chinese 'drilled' wells for brine using a percussion system in which a heavy, chisel-shaped bit suspended from a rope was jerked up and down by relays of men bouncing on a spring-board, thus progressively pounding the hole deeper 11 The Development of Marine Rotary Drilling A v~riation of this method used in Europe and America in the eighteenth century was called 'spring pole drilling' A large metal bit was suspended from a flexible wooden pole by a long rope and allowed to drop to the bottom of the well The bit chewed briefly into the formation, like a man stabbing with a chisel, before the springing pole bounced it back up As this happened the length of the rope would be extended a little by the 'driller' controlling it at the surface, so that the bit struck with an unvarying force on each successive blow and chewed in a little deeper on each downward stroke As the bit was reciprocated up and down in this manner the rope twisted slightly and varied the position of each blow on its descent, resulting in a roughly circular hole being dug The Development of Marine Rotary Drilling Large quantities of cuttings naturally collected at the bottom of the hole, and as this was almost as narrow as the bit, the cuttings had to be removed by a self-shutting container, called a bailer, which was periodically lowered to the bottom When this method was eventually introduced to western countries iron bits were used, drilling holes of only 21f2to inches (7 to 10 centimetres) in diameter Wells were seldom more than 240 feet (75 metres) deep, but there is evidence of a brine well being drilled to just over a thousand feet (305 metres) in the USA in the early 1840s To hold back the wall ofthe hole, this American well was 'cased' with lengths of wood shaped into half tubes and wrapped with twine The Chinese, on the other hand, cased their wells with hollow bamboo sticks, and are said to have drilled to depths of more than a thousand feet by this method Spring pole drilling was limited by the weight that the wooden pole could repeatedly lift without breaking, and of course this weight included that of the rope, which got progressively longer with the depth of the well If the rope broke and fell to the bottom of the well with the bit or the bailer attached, the driller had to improvise a method of retrieving, or 'fishing', for the 'fish', as the lost equipment was termed Various gadgets were developed for this purpose and thus the forerunners of today's efficient fishing tools were devised In the early part of the nineteenth century, whale oil was the most commonly used fuel for lighting lamps in America and Europe The US, Britain, Norway and many other countries had large fleets of whalers, and other types of oil were not considered commercially important In America, 'rock oi!' was frequently found seeping into brine wells drilled near salt creeks, and at first it was regarded as no more than a nuisance However, the busy whaling fleets quickly depleted the stocks of whales and it was recognised that sooner or later another source of lamp fuel would be required The value of the black oil that was often found seeping out of the ground in many places was eventually realised, and this rock oil was henceforth harvested However, it was to be some years before oil was specifically drilled for CABLE TOOL DRILLING The early nineteenth century saw the rapid mechanisation of many industries in the western world, and about 1850 a revolutionary new method of drilling called cable tool drilling was introduced It utilised a steam engine with a crank, giving a long, regular, reciprocating motion to a heavy metal bit on the end of a rope, and it was found to be much more efficient than the old percussion method that utilized a spring pole The engine was also used The Development of Marine Rotary Drilling the hoist the drilling, bailing and fishing tools in and out of the well, and the process of drilling a well thus became much faster and more efficient and was almost completely mechanised, just as it is today As the cable tool method gained wider favour, a wide range of ingenious devices were developed to overcome problems encountered and make the job of drilling easier and safer The now familiar drilling derrick, then made of wood rather than steel, but tall enough to house lengths of drilling, bailing or fishing t001s, was introduced Much heavier bits and more robust equipment could now be used with the steam power, and wire instead of fibre rope enabled deeper wells to be drilled Iron casing, replacing the old wooden sheathing, could now be driven into the hole length by length as the well got deeper, so as to retain the wall and to make it easier to extract any minerals that were eventually found The Development of Marine Rotary Drilling Cable tool rigs were particularly useful for drilling medium-hard rocks, but the softer rocks encountered could not withstand the spudding, or jabbing, action of the bit, and holes often caved in or allowed too much water to seep into them for drilling to continue A new type of cylindrical steel casing was developed to replace the old iron type, and if caving occurred, lengths of it were screwed together and lowered into the hole to seal the wall of the hole When the casing reached the bottom, drilling then continued using a slightly smaller bit that could just run through it As each new problem zone was encountered, so more casing was run inside the last 'string', and a correspondingly smaller bit was used to drill out the next section In those days oilmen were not blessed with the huge variety of tools that now enable them to overcome nearly every kind of downhole problem, so if the cable tool well encountered too many hitches, and so many casing runs had to made that the bit got too small to drill with, the hole would have to be abandoned, often before reaching its target depth The method was, therefore, slow and inefficient, but to the early pioneers of the oil industry it represented the pinnacle of drilling technology at that time One of these pioneers, a retired railroad conductor named 'Colonel' Edwin L Drake, is now famed for supervising the drilling, between June and August 1859, of a cable tool well at Oil Creek near Titusville, western Pennsylvania, USA, that is considered to have founded the oil industry as we now know it Drake did not actually own the well; a New York lawyer named George H Bissell owned the land it was drilled on, and his was the idea to drill specifically for oil, since the area had been noted for its surface seepages of oil In any event, the Drake well, as it is now known, successfully located an oil reservoir at a depth of only 691f2feet (21 metres), and oil flowed at a rate of about 19 barrels a day, or 3,000 litres, which was phenomenal for those days Bissell became a founder of the Pennsylvania Rock Oil Company, and further successes with cable tool drilled wells made that state the leading oil producing area for the next fifty years Its lead stimulated the growth of the drilling industry in other areas, notably in Canada, Poland and California From the oilfields of these areas drillers took their knowledge of the newly successful cable tool drilling techniques all over the world, and the worldwide drilling industry thus began By the turn of the twentieth century, after fifty years of continuous use and development, it was possible to drill wells by the cable tool method down to about 3000 feet (1000 metres) in favourable conditions The heydey of the method, however, was the period from 1900 until the great economic depression of the 1930s, and many of the best improvements came during this time Steel derricks replaced the old timber structures, and bits became larger and tougher The most important development, however, was the 15 The Development of Marine Rotary Drilling introduction of the cementing of casing This was first done in 1903 when some liquid cement was dumped from a bailer into a well and a string of steel casing was lowered into it A few days later, when the cement had set, the hard cement inside the casing was drilled out The cement in the annulus between the casing and the wall of the hole was found to have sealed off a zone of water in the formation, and it had also anchored the casing to the wall of the hole This success was further improved on when in 1910 a procedure was introduced for pumping a measured amount of liquid cement down a hole A volume of cement was held between two wooden plugs, spaced one above the other, and was pumped down the inside ofthe casing, round its bottom end, and up the narrow annulus outside, where it was left to set hard Although all the cement was expelled from the 'shoe' at the bottom of the casing, the plugs were retained inside it, but these were drilled out when drilling resumed with a smaller bit Again it was found that the cement in the annulus between the casing and the hole had set hard, and henceforth in this manner each section of casing was run into the hole and cemented to surface, thus overcoming many of the formation difficulties previously encountered Basically, the same procedure is still used today in 'cement jobs', and one of its several virtues is that it allows wells to be carefully planned in advance from start to finish in fields where the formation types are known By 1918 the world's deepest well, drilled by the cable tool method, was 7,386 feet (2,251 metres) deep, and the technology of cable tools nearly at its zenith It was possible to 'spud', or start drilling, one of these wells with a 24-inch (61 em) diameter bit and, if necessary , cement up to seven separate strings of casing, from 20-inch (51 em) diameter down to 5-inch (12.7 em), as problems in the well were encountered However, the rotary system, in which the drill bit was rotated under power on the end of a steel tube instead of being reciprocated on the end of a wire, was also being developed, and by then had become the preferred method for drilling holes deeper than 4,000 feet (1,219 metres) It was recognised that the great disadvantage of the cable tool method was that there was no means by which a drilling fluid could be circulated so that cuttings could continuously be brought to the surface, and so that the wall of the hole, together with any oil, water or gas in it, could be held back During the 1920s a type of combination rig was developed which could employ both cable tool and rotary methods at different stages of the well when it was thought profitable to so, but the rotary type of rig was by this time rapidly gaining favour Up to 1930 there were still far more active cable tool rigs than rotary rigs, and that was the situation obtaining when the pre- 16 The Development of Marine Rotary Urilling war depression drastically reduced drilling activity all over the world By that time the deepest well yet drilled by the rotary method was just over 10,000 feet (3,050 metres) deep When drilling activity resumed after the depression the industry had become leaner, fitter and more competitive, and deeper wells were required to find and exploit new oil reserves to meet the world's revived thirst for energy Cable tools, which could rarely drill more than 60 feet (18 metres) a day, had virtually reached the limits of their technology, but rotary rigs, which could, in favourable conditions, drill 2,000 feet (609 metres) in eight hours, seemed to offer unlimited scope for improvement As a result, after 1930 cable tools never recovered their previous popularity, and they were gradually superseded by the rotary system The deepest cable tool well ever completed was the Kesselring No NYS Nat Gas Corp., completed in 1953 at 11,145 feet and taking over 21f2years to drill Today the cable tool method is rarely used ROTARY DRILLING Rotary drilling evolved from the carpenter's method of boring a hole in wood with a rotating tuol which itself flushed out the cuttings The derrick, initially introduced for cable tool drilling, was now employed as a simple crane from which a hook, suspended from a block and tackle, was moved up or down by a wire running over a hoisting drum called a drawworks The bit was secured to the bottom of a string of steel pipes, and was rotated by power transmitted by an engine on the surface A rotary drilling machine was patented in 1845 but the system was first used in Texas in the early 1890s in an attempt to solve the soft rock problem that had plagued cable tools there Up until the end of the 19th century, cable tools were still favoured for most drilling situations In January, 1901 Anthony Lucas's well at Spindletop, near Beaumont, Texas, was completed with a rotary rig after several attempts to complete it with cable tools failed due to running quicksand The quicksand was easily held back with casing when the rotary equipment was brought in and the well finally blew out, producing 84,000 barrels of crude oil a day from a depth of a little over 1000 feet The 'gusher' blew all the drill pipe out of the 60-foot high derrick and shot more than 200 feet into the air above it, proving beyond doubt the value of rotary rigs On the strength of its Spindletop success rotary drilling soon held sway in the US Gulf coastal areas and was competing strongly with the cable tool method elsewhere Although the early equipment was radically different to that used today, the concept of rotary drilling is fundamentally unchanged 18 Glossary of Marine Drilling terms Glossary of Marine Drilling terms while jack-ups usually have open-girdered legs edged with teeth by which they are jacked up or down LOST CIRCULATION MATERIALS: Material such as walnut shells, mica, olive stones, etc., added to drilling fluids or cement slurries to help stem the loss of drilling fluid into a formation LENGTH O.A.: The overall length of a vessel, meaning her extreme length LIFEBOATS: Survival craft carried by all offshore drilling installations They are normally diesel-engined and totally enclosed Some types are almost circular in shape LIFEBOAT DRILL: A crew survival training exercise held at frequent intervals, often in conjunction with a fire drill LIFERAFTS: Automatically inflating rafts that are carried in addition to the lifeboats LIGHTSHIP WEIGHT: The displacement of a drilling vessel as built, without her most of her equipment, stores, ballast, etc LINER: A string of narrow casing which is set inside the bottom of the lowest string of well casing and runs to the bottom of the well, usually serving as the 'oil string' Tubing can be installed in this to extract well fluids LOST TIME ACCIDENT: An accident in which a period of working time is lost by a rig crewman LOWER MARINE RISER PACKAGE: An assembly comprising the flex or ball joint, an annular blow-out preventer, hydraulic accumulators, sections of riser and the riser slip joint, all of which can be detached from the rest of the BOP stack in an emergency to allow the drilling unit to move off location whilst leaving the well secure L.T.A.: A lost time accident, q.v -MMACHINE ROOM: The engine room, where the main diesel engines of a rig are located MAKE-UP: The act of screwing one joint of pipe, etc onto another LIST: A permanent inclination of a vessel, caused, for example, by bad weight distribution or by a flooded compartment LOCATION: The place at which a well is to be drilled, and usually referring to the area immediately around it A supply boat is said to be 'on location' when she is on station at or near the rig The geographical position of drilling locations are measured very precisely by electronic equipment LOG: A systematic and permanent record of data On a drilling rig many different types of log are obtained including well logs, machinery logs, mud logs, etc Some are continuous recordings, others obtained when required LOGGER: A mud logger, q.v LOGGING SHACK: A portable cabin in which mud logging instruments are installed and the loggers work LOST CIRCULATION: The loss of quantities of drilling fluid into a formation This may be due to caverns, fissures or permeability It is evidenced by lack of returns of drilling fluid and stopped by the pumping downhole of lost circulation materials, q.v 318 MAKE-UP CATHEAD: The cathead on the doghouse side of the drawworks MAKE-UP CHAIN: The chain connecting the arm of the make-up tong with the automatic cathead It is tensioned to provide the torque for tightening a connection MAKE-UP TONG: A large mechanical steel wrench suspended by a wire from the derrick and used to tighten the 'male' ('pin') end of a joint of pipe when this has been stabbed and spun up inside the 'female' ('box') end of another pipe It is also used to back-up the lower joint when a connection is being loosened by the break-out tong The arm of the make-up tong is connected to the drawworks by a chain, and a snub-line tethers it to a sampson post A torque gauge is fitted to its end MAKING A CONNECTION: The operation of screwing a new joint of driJI pipe onto the top end of the drill string This is done when the kelly has travelled down through the rotary table almost as far as it will go The kelly is often made up into the new joint while this is standing in the mousehole, and the joint is then stabbed into the drill string in the rotary 319 Glossary of Marine Drilling terms MAKING A ROUND TRIP: The long operation of pulling the drill string completely out of the hole for some reason, such as changing the bit, and then returning it to the hole It can take eight hours or more in a deep well MAKING HOLE: Rotating the drill bit and deepening the hole Also called 'drilling ahead' MAN OVERBOARD DRILL: A recovery exercise, usually using a dummy thrown overboard from a rig, performed periodically with the rig standby vessel to the operator's requirements MANIFEST: A list of cargo loaded or back loaded by supply boat or helicopter MANIFOLD: A control point in a piping system at which flow can be directed in a number of ways On the drill floor there is a choke manifold for the control of fluids returning from the well See 'choke and kill manifold' MARINE CREW: The mariners barge master, barge engineer or as the maintenance of lifesaving ations CROs, radio operators crew aboard a rig who, under the direction of the barge operator, attend to marine work such and fire appliances, and perform boat operand sometimes the medic are also marine MARINE RISER: The large-diameter pipe connecting the BOP.stack to the drill floor of a semi-submersible or drill ship, through which the drill string passes to the well and through which returns of drilling fluid pass from the well to the rig MARINE SUPERINTENDENT: The rig operator's staff member responsible for the day-to-day maintenance of all marine equipment aboard the fleet's units MATERIALS CO-ORDINATOR: A person responsible for the movement and supply of equipment and stores needed for a well programme Some oil companies keep a materials co-ordinator aboard during the period of hire, while others leave this work to the company man MATSMAN: A common abbreviation used for the materials co-ordinator M.D.: Measured depth, q.v MEASURED DEPTH: Measured depth, which is the total actual length of a 320 Glossary of Marine Drilling terms drilled hole taking account of every deviation from the vertical MEASUREMENT WHILE DRILLING: A technique of logging certain information about downhole conditions through sensors in the bottom hole assembly Information is then sent to measuring devices and a digital display on the drilling rig by means of pulses transmitted by telemetry through the mud This requires rotary drilling to be stopped only for a short period, and does not interrupt drilling at all if a downhole motor is being used It is often used in directional drilling to measure angles of inclination and direction Abbreviated to MWD MECHANIC or RIG MECHANIC: A crewman whose job is to maintain the rig's machinery in good running order Many mechanics are former marine engineers, although aboard a rig they may be called upon to repair items of drilling machinery in addition to the main diesel engines MEDIC: A qualified nurse who is on call 24 hours a day for treating minor injuries He usually doubles as a clerk MEZZANINE DECK: A name sometimes used to describe the cellar deck beneath the drill floor MILL: A special tool with a rough, sharp and very hard cutting head used for milling, q.v Mills are made in many shapes and either fit on the end of a drill string or are incorporated within it like a reamer MILLING: Using a mill to grind down metal debris in the hole, remove sections of casing when sidetracking, or for reaming out tight spots in the hole MOBILE OFFSHORE DRILLING UNIT: A marine drilling platform which us capable of being moved from one location to another Semi-submersibles, jack-ups, drill ships and drilling barges all come into this category, whereas fixed platforms not Abbreviated MODU M.O.D.U.: A mobile offshore drilling unit, q.v MONEL: A type of non-magnetic drill collar MONKEY BOARD: A narrow platform, like a diving board, from which the derrickman manipulates the top ends of stands of drill pipe when making a trip The board can move up or down to reach pipe of different heights MOONPOOL: The void space cut in the deck of a semi-submersible, or 321 Glossary of Marine Drilling terms inside a drillship, which is open to the water and through which sub-sea equipment is run Commonly, if wrongly, also used to describe the area of the cellar deck immediately round the void A small moonpool is also used for running diving equipment Glossary of Marine Drilling terms MUD LOGGER: A trained analyst who records well log data using machinery installed in the logging shack Loggers are sometimes qualified geologists MORNING REPORT: The company man's report sent to 'town' at or about 0600 daily, detailing all rig operations during the last 24 hours MUD LOGGING: A continuous logging process carried out by mud loggers in which the presence of any hydrocarbons in the drilling fluid is recorded on a graph Mud loggers constantly monitor this equipment in the logging shack MOTORMAN: The mechanic's assistant responsible for keeping the engine log, records of lubricants used, and for other minor engine room and associated work A mechanic on an American rig is usually termed a 'motorman' MUD PITS: Large holding tanks for drilling fluids, grouped together in the mud room MOUSEHOLE: A deep tube suspended below the drill floor from which a single joint of drill pipe can be taken when making a connection The joint is made up to the kelly while in the mousehole, then pulled out, transferred to the rotary and made up to the drill string This is called making a 'mousehole connection' MUD: Liquid drilling fluid circulated down the hole and back to the rig MUD PUMP: A large reciprocating pump for forcing drilling fluid through the circulation system There are usually two or three main mud pumps MUD ROOM: A large internal space where mud pits and, frequently, mud pumps and other associated equipment are installed MUD SCREEN: A screen on the shale shaker, through which mud is strained under vibration to remove cuttings MUD ADDITIVES: Chemicals mixed with mud to alter its chemical or physical properties MULTIPLE ZONE COMPLETION: A method used to complete a well so that production can be obtained simultaneously from two or more formations at different depths MUD BUCKET: A cylinder fitted round a connection on the drill floor to save mud from being spilled when the connection is broken -N- MUD CAKE: See filter cake NATURAL GAS: Hydrocarbons occurring naturally in a gaseous form in a well Methane is the main constituent, but small percentages of several other gases are present in natural gas, as well as contaminants such as hydrogen sulphide (sour gas) and water vapour MUD CLEANER: A machine used in the drilling fluid treatment process to remove solids from returning mud and conserve barite and fluid Desilter cones are mounted over a motorised shaker screen which removes drilled solids, while the barite and liquid component of the mud is returned to the circulating system NIGHT PUSHER: The junior toolpusher, who normally works the night tour from 18.00 hours to 06.00 hours Sometimes called the 'tourpusher' MUD ENGINEER: The contracted specialist who supervises the correct mixing and conditioning of mud, which is usually supplied by his company Often called the 'mud man' NON-MAGNETIC DRILL COLLAR: A type of drill collar used in the bottom hole assembly when magnetic survey tools are going to be run Sometimes called a 'monel' MUD LABORATORY: The mud engineer's 'office', in which he tests mud samples -0- MUD MAN: The commonly used term for the mud engineer 322 O.D.: Outside diameter Drilling tubulars are usually referred to by their outside diameter, e.g 5" drill pipe, 9112" drill collar 323 Glossary of Marine Drilling terms Glossary of Marine Drilling terms OFFHIRE SURVEY: An independent survey of a drilling rig made at the end of a hire period when quantities of consumables remaining onboard are checked, as well as structural damage to the unit performing work outboard of the rig structure, when there is a possibility of falling into the sea The standby vessel is called to close standby at such times and a lifevest and safety harness has to be worn by the permit holder OFFSHORE INSTALLATION MANAGER: The person appointed under the Mineral Workings (Offshore Installations) Act 1971to be legally responsible for the safety, health and welfare of all persons on or about a British offshore installation while drilling or production is in progress -p- OIL BASE MUD: Mud mixed using a base of diesel oil instead of water It is useful when drilling shales, deep high-temperature holes and salt formations, and in directional drilling and for freeing stuck pipe OIL SAND: Sandstone containing oil in its pores P A SYSTEM: The public address system by which announcements are normally made aboard a rig PACKER: A tubular sealing device that can be lowered into the casing, liner or open hole and made to expand flexible rings at its circumference in order to isolate a section of the hole, e.g for well testing purposes Many different designs are made for a variety of uses Packers generally have a hole through their stems for circulating drillig fluid or for running wire line tools, and they may have box and pin connections for the attachment of other tools OIL ZONE: A formation which a hole has penetrated from which oil may be produced The oil zone usually lies under the gas zone and over the water zone in a reservoir PAY SAND: The zone which is the target area of the drilling operation; alternatively a formation which is already producing O.I.M.: Offshore Installation Manager, q.v PELICAN HOOK: A device used by anchor handling vessels to secure a rig's anchor chain temporarily on the after deck while connections or disconnections of attachments are made ONHIRE SURVEY: An independent survey of a drilling rig made at the start of a hire period, to determine quantities of consumables onboard and the general condition of the unit OPEN HOLE: A well in which no casing has yet been set This is undesirable if there is a likelihood of pressurised hydrocarbons entering it, so casing is set soon after each section of hole has been drilled OPERA TOR: The company to whom a rig is contracted to drill a well, and which is either the sole financier ')fthe project or the representative of a consortium of partner companies The name 'operator' is also given to the person who operates a unit of machinery offshore, e,g, the wireline operator OUTER CONDUCTOR: A short string of wide-gauge casing, usually 30" bore, which is used as the foundation string in deep wells Also called the 'surface conductor' OVERSHOT: A 'female' ended downhole tool used in fishing operations for lost or stuck pipe, etc., when it is lowered over the end of the fish to obtain a grip Its male counterpart is a spear, q.v OVERS IDE WORK PERMIT: A work permit issued by the OIM to a person 324 PENETRATION, RATE OF: The rate at which the drill bit is cutting through the formation, expressed in feet per hour Abbreviated to 'ROP' PENNANT: A length of strong wire rope with eyes at its ends for making connections, used for a variety of purposes in anchor-handling Many pennants of different lengths and load capacities are used in an anchor-handling operation PERFORATE, TO: To fire steel projectiles through casing or liner, and its surrounding cement, that has previously been set through a formation expected to produce The gun firing the bullets is fired electrically from the surface PERMANENT GUIDE BASE: A steel frame, usually square and with four corner posts, that is lowered onto the temporary guide base following the running of the outer conductor casing to serve as the foundation for the wellhead and BOP stack The guidelines run through the corner posts, and these are used to locate the BOP stack when it is run PERMEABILITY: The ability of hydrocarbons to flow through the pores of a rock 325 Glossary of Marine Drilling terms Glossary of Marine Drilling terms PETROLEUM: Hydrocarbon oil or gas obtained from the earth's subsurface rocks PIGGY BACK: A back-up anchor used in tandem with a main anchor when the main anchor is unable to hold the required chain pre-tension on its own Piggy backs are usually lighter than main anchors PILOT HOUSE: The wheelhouse and navigation centre of a rig, usually found at the forward end near the centreline PIN CONNECTOR: A pressure-sealed device used to connect the marine riser to the wellhead when drilling through large diameter conductor casing that prevents the use of a blow-out preventer stack Pin connectors are used when shallow gas pockets might be encountered PIPE: Oilfield tubulars such as drill pipe, collars, casing and tubing PIPE RACK: A row of spaced parallel beams on the deck of a rig, on which drilling tubulars are laid down for storage PIPE SPINNER: A hydraulic wrench used in place of a spinning chain to spin up a connection prior to torquing-up PITS: Large tanks in which drilling fluid is held prior to pumping down the well by the mud pumps They are usually sited near the mud pumps PITCH: The forward-and-backward way, particularly in a head sea oscillating motion of a vessel in a sea- PLATFORM: The name sometimes used to describe a mobile drilling unit on which a drilling rig is erected Also the term used commonly offshore to describe a self-contained fixed production platform PLUG: A device inserted into a drilled hole to block the passage of fluids Plugs may be made of rubber, cement, or other substances, and some can be drilled out or retrieved when no longer required PLUG & ABANDON, TO: To seal the top of a well with a cement plug and abandon it As much casing as possible is retrieved, together with the wellhead and sub-sea equipment, and the sea-bed is left clear of debris Dry holes are usually plugged and abandoned POD: A sub-sea container, mounted on the BOP stack, that houses control 326 valves and actuators for operating the BOP hydraulics Two pods are usually fitted for full redundancy, each connected by a flexible hose to controls on the drillinge rig PONTOON: A hull of a semi-submersible rig, at the lower end of its columns, which provides buoyancy as well as space for ballast, fuel, water and drilling fluids There may be two or more pontoons, depending on the rig's design P.O.O.H.: Abbreviation used for pulling out of the hole, which is the operation of withdrawing the entire drill string from the well bore for some purpose, such as changing the bit POSSUM BELLY: The name often given to the trip tank, which is a tall and narrow cylindrical tank holding drilling fluid and used for determining whether formation fluids are entering the wellbore during the tripping operation, or whether drilling fluid is being lost into the formation POWER SWIVEL: A type of drilling swivel that is turned by electric or pneumatic power and replaces the rotary table, master bushing, kelly and circulating swivel It is sometimes used for light drilling operations PRE-LOAD: A load placed on a jack-up rig before it is jacked fully up to its working air gap, to test the penetration of individual legs With the rig at about feet air gap, pre-load tanks in the hull are filled with sea water to achieve even total weight distribution on the legs After a test period of several hours the air gap at each leg, which may have changed during this time, is adjusted so that the rig is standing level, after which it is jacked to the desired air gap PRESSURE TEST: A test performed on an item of equipment that is designed to withstand high pressures from fluids BOPs and associated drilling fluid circulating equipment are frequently pressure tested, especially as the hole gets deeper PRE-TENSION: The load which a rig's anchor chain has been proved to withstand without breaking the anchor out of the ground Pre-tcnsion proving is carried out before slacking back to a working tension PREVENTER: A blowout preventer, q v PRIME MOVER: One of the main engines which are the source of power on ang 327 Glossary of Marine Drilling terms Glossary of Marine Drilling terms PRODUCTION: The process of bringing hydrocarbons to the surface from a sub-surface reservoir for onward transport to the refinery ashore RAM: A closing and sealing device in a BOP stack The rams are activated by hydraulic pressure when a blow-out is threatened, and can be locked shut PRODUCTION PLATFORM: A platform, which may be either fixed or floating, designed chiefly for production, although development drilling may take place from it RAT HOLE: A tube recessed below the drill floor, into which the kelly, kelly cock, kelly bushing, kelly spinner and swivel are temporarily placed when 'tripping' is in progress PRODUCTION WELL: A well from which oil or gas is produced R.C.V.: Abbreviation for remote-controlled vehicle, which is a pilotless submersible deployed from a rig to perform subsurface tasks Usually known as an ROV, q.v PROPULSION ROOMS: Compartments in the pontoons of a semi-submersible rig in which propulsion machinery is housed In a diesel-electric rig the diesel engines are on the main deck level and the electric motors that drive the propeller shafts are in the propulsion rooms P.S.I.: Pounds per square inch: the unit of pressure normally used in drilling REAMER: A downhole tool sometimes included in the bottom hole assembly, looking like a drill collar with short fins on which there are cutters It is used for smoothing and enlarging the wall of the hole, stabilizing the bit, straightening the hole where doglegs occur, and in directional drilling If the cutters revolve the tool is called a roller reamer 'P' TANK: A silo in which powdered drilling material such as cement, barite or bentonite is stored in bulk on a drilling unit On a semi-submersible the 'P' tanks are usually in several of the columns REAMING: The operation of enlarging the hole by re-drilling it with a reamer PULL OUT OF THE HOLE, TO: To withdraw the drill string completely from the hole for some purpose, such as for changing the bit RESERVOIR: A subsurface formation in which the pores of the rocks hold hydrocarbons PUMP ROOM: The compartment in a semi-submersible rig in which the ballast, bilge and other pumps are sited It is usually in the pontoons REVERSE CIRCULATION: The circulation of the drilling fluid in the opposite direction to the normal way, i.e down the annulus around the drill pipe and up through the centre of the drill pipe This is sometimes done to alleviate problems in the hole PUP JOINT: A short joint of any kind of tubular, such as drill pipe or marine riser, used to make up a required total length in a string -RRACKING ARM: A large hydraulically controlled telescopic arm used on the drill floor for moving, guiding and stabilizing pipe of various diameters RACK PIPE, TO: To stand pipe back on end in the setbacks inside the derrick as they are pulled out of the hole during tripping RADIOACTIVE WELL LOG: A record of the radioactive characteristics of a formation measured by wireline logging equipment that is lowered into the hole RADIO ROOM: The communications centre aboard an offshore drilling unit 328 RIG: Strictly speaking, the derrick and drilling equipment that are mounted on a platform such as semi-submersible, drill ship, etc In practice, however, the drilling unit itself is commonly referred to as 'the rig' RIG AIR: The rig's compressed air supply, maintained by air compressors and used for many purposes around the rig RIG DOWN, TO: To dismantle and secure certain items of equipment following completion of a well, when preparations are made for the rig-move to the next location RIG FLOOR: An alternative name often used for the drill floor RIG SUPERINTENDENT: The drilling contractor's staff member who is responsible for managing the day-to-day operations of the drilling unit He 329 Glossary of Marine Drilling terms usually works from the office in 'town' and maintains regular contact with the toolpusher or aIM on the rig, although some companies employ rig superintendents onboard their rigs He may be called the 'drilling superintendent' in some companies RIG UP, TO: To prepare a drilling unit ~nd its equipment for the start of drilling following a rig-move to a new location Glossary of Marine Drilling terms drive may be applied by the rotary table or by a downhole drilling motor ROTARY HELPER: A name sometimes used (particularly on American rigs) for a roughneck or floorman ROTARY HOSE: A flexible hose that connects the top end of the stand pipe with the gooseneck connection at the swivel, through which drilling fluid enters the drill string R.I.H.: The usual abbreviation for running in the hole RISER: The steel conduit connecting a floating drilling rig with the wellhead, down which all drilling tools, casing, etc are guided to the well and up which the drilling fluid returns from the well to the rig It also serves as the running string for the BOP stack Properly termed the 'marine riser' RISER ANGLE: The angle from the vertical made by the riser This must be within a certain tolerance to avoid damage to the riser It is usually monitored by acoustic transponders which send signals to instruments on the rig RISER FLEX JOINT: The ball joint, q.v RISER TENSION: The amount of tensile load, usually measured in pounds, set on the riser tensioner wires by adjusting the tensioner air pressure As the hole gets deeper and heavier mud is used, the tension is increased RISER TENSIONER: The system of wires, sheaves and cylinders, operated by pneumatics and hydraulics, that maintain a constant tension on the riser support wires to avoid the riser's collapse ROLL: The side-to-side oscillating motion of a vessel in a seaway, particularly in a beam sea Drill ships are more susceptible to rolling than semi-submersibles are Two or three degrees of roll from the vertical would be considered unusually large on some types of semi-submersible, but different types have their own motion characteristics ROTARY BUSHING: A circular steel cup-shaped lining that fits into the rotary table and into which the kelly bushing is inserted during drilling When the kelly bushing is removed, slips can be wedged into the space between the rotary bushing and drill pipe running through the rotary Also called the master bushing ROTARY DRILLING: Drilling with a bit which is rotated while a force is applied above it; the normal method of drilling an offshore well The rotary 330 ROTARY TABLE: The underdeck housing for the mechanism in the centre of the drill floor that drives the kelly and turns the drill string and bit All downhole tools, casing, etc are run through its opening ROUGHNECK: A member of the drill crew who performs manual tasks on the drill floor, such as making and breaking connections, racking pipe back, etc Also called a floorman or rotary helper ROUND TRIP, MAKING A: Pulling the entire drill string out of the hole for some purpose, such as changing the bit, and then running it back in This can take many hours in a deep well ROUST ABOUT: A general-purpose hand who may be called upon to carry out virtually any manual task aboard the rig for either the drilling or marine departments, e.g laying down drill pipe, standing in for roughnecks during meal breaks, preparing loads for boats, painting or washing down, etc R.O.V.: Abbreviation for a remotely operated vehicle, which is a small remote-controlled submersible sometimes deployed for sub-sea tasks such as repairs or inspections to underwater equipment The ROV often has mechanical arms which can perform most of the functions of a human diver RUCKER WIRES: A name sometimes used for the riser tensioning wires RUN CASING, TO: To lower steel casing into the well joint by joint to line it This is usually done by contracted specialist casing hands RUN INTO THE HOLE, TO: To lower the drill string into the hole Usually abbreviated RIH -8SACK: A measure of volume often used in the drilling industry for dry powders such as cement, barite and bentonite A sack of cement measures one 331 Glossary of Marine Drilling terms cubic foot and weighs 94 lb A sack of barite weighs about 100 lb and there are 22.5 sacks of barite to a ton There are 39 sacks of bentonite to a ton Sacks is often abbreviated 'sx' SACK ROOM: The compartment where the bagged and drummed constituents and additives required for mixing the drilling mud are stored, usually close by the mud pumps SAFETY AWARD: An award is given by some drilling contractors to the crews of their rigs in recognition of passing a certain number of days without a lost-time accident SAFETY COMMITTEE: A committee formed on a rig for the purpose of monitoring and improving the standard of safety awareness amongst its crew SAFETY MEETING: A regular meeting held by sections of a rig crew to discuss aspects of safety in their work area or elsewhere onboard The minutes of the safety meeting are then discussed by the safety committee at their own meeting Glossary of Marine Drilling terms SCHLUMBERGER: The name given to the wireline logging equipment installed on a rig that is often owned by a company of the same name Schlumberger was a French scientist who first developed the technique of electric wireline logging SCRATCHER: A multi-pronged device fitted round a joint of casing to make contact with the wall of the hole, to scrape of excess filter cake and to improve the chances of a good bond when cement is pumped into the annulus SEMI-SUBMERSIBLE: A type of vessel the draught of which, by flooding certain compartments, can be increased to submerge much of its structure, either to give a degree of stability not attainable in conventional monohull vessels, or for some other purpose, such as to float another vessel onto its deck The hull or hulls may be designed to rest on the sea-bed in certain conditions, but most semi-submersible rigs drill whilst floating See also 'column stabilized semi-submersible' SETBACKS: The areas inside the derrick adjacent to the V-door where drill string tubulars are 'set back' , or stood on end, when they are out of the hole temporarily Their top ends are racked back between fingers SAFETY OFFICER: A member of a rig crew appointed to be responsible for convening safety meetings and for implementing improvements in rig safety All British-registered vessels must have a safety officer amongst the crew The safety officer is often the bargemaster SETTING CASING: The operation of running casing and then fixing it in place by pumping cement into the annulus between it and the surrounding wall ofthe hole SAND LINE: A long, narrow diameter wire line kept on the drill floor for downhole jobs such as retrieving the 'Totco' tool, q.v SHALE: The type of rock most frequently encountered during offshore drilling, composed of small silt and clay particles SAND TRAPS: Tanks in the drilling fluid circulation system in which the fluid is recovered after passing through the shale shaker SHALE SHAKER: The vibrating screens across which the drilling fluid returning from the hole is poured to strain off the liquid and deposit the solid particles SATCOMS: A satellite communications system installed on a rig to enable a speedier flow of messages to and from shore bases than by conventional radio-telephone or telex Recognised by a large dome housing a dish aerial SHOCK ABSORBER: A tubular tool used in the drill string to absorb shocks and vibration and thereby extend the life of the bit and minimise damage to the drill string SATELLITE WELL: A well drilled independently of a platform by a mobile unit but tied in to the platform for production purposes by a sea-bed pipeline Most platform wells are direction ally drilled form the platform SHOW: A trace of oil or gas found in cuttings, samples or a core recovered from the well SATNAV: Satellite navigation equipment, used for positioning the rig on the location and for navigation during ocean transits SIDETRACK, TO: To divert the drill bit round an obstruction in the well, such as stuck pipe This is done using directional drilling techniques and tools such as a whipstock 332 333 Glossary of Marine Drilling terms SINGLE ZONE COMPLETION: A simply type of well completion in which packers not separate producing zones SKIDDING BEAMS: Rails along which the drilling package of a cantilevertype jack-up rig into its drilling position SKIDDING UNIT: A thrusting unit with hydraulically-operated rams that moves the drilling package of a cantilever-type jack-up rig along the skidding beams SLANT DRILLING: A technique of drilling direction ally from a jack-up rig in which the drilling derrick is tilted to an angle of about 30 degrees from the vertical SLICKER SUIT: A suit of waterproof overalls worn by drill crews when making a 'wet trip' or when washing down SLIP & CUT, TO: To move the drilling line over the sheaves of the hoist a certain distance and cut off a length of the line, so that the sheaves are not always in contact with the same parts of the line, with consequent risk of overstressing SLIP JOINT: A telescopic joint inserted near the top of the marine riser to absorb the vertical motion of the drilling unit when heaving up and down in a seaway SLIPS: Tapered steel wedges that are inserted between the rotary bowl and a tubular joint to grip the string temporarily, e.g while it is disconnected from the hoist when making a connection The wedges are hinged so that they effectively wrap around the tubular to provide a grip around its circumference Different types of slips are used for drill pipe, collars and casing Glossary of Marine Drilling terms SNUB LINES: Wires connecting the arms of each set of manual tongs to sampson posts at either side of the rotary table, to arrest their tendancy to turn round when they are acting as the back-up tong SPEAR: A fishing tool which'stabs the end of a joint of pipe that has been lost or stuck in the hole It is the male counterpart to the overshot, which goes over the end of the fish SPIDER: A circular steel frame which is positioned round the rotary opening when the marine riser or other tubulars are being run to act in the same way as a set of slips Each joint of riser is passed through the spider and is clamped tightly by arms or a hydraulic device while the next joint is connected SPIDER BEAMS: Movable steel beams in the moonpool of a floater which can be positioned beneath the BOP stack to support it during the attachment of riser or during overhaul or repairs SPINNER HAWK: An alternative name for the pipe spinner, q.v SPINNING CATHEAD: A name sometimes used for the make-up cathead SPINNING CHAIN or LINE: A chain used to start the operation of screwing two joints of drill pipe together on some rigs SPOTTING: Pumping a slug of oil down through a stuck drill string and up its annulus to the position where it is stuck against a formation The oil then soaks into the filter cake, sometimes freeing the pipe SPUD CANS: Tanks on the bottom ends of the legs of a jack-up rig which 'spud', or penetrate into the sea-bed at the start of the jacking-up operation They are filled with sea water SLUG: A quantity of heavy drilling fluid that is pumped into the top of a joint of drill pipe before it is disconnected so that it will not be full of fluid when the connection is broken SPUD IN, TO: To commence drilling a well with a hole opener SLUG PIT: The small mud pit where heavy mud for slugging is kept SPUD MUD: Mud specially mixed for the spudding-in operation It is claybased and normally contains a bentonite gelling agent to prevent sloughing in the conductor hole SLUSH PUMP: An alternative name for a mud pump SLURRY: A semi-liquid mixture of cement powder and water that is pumped up into the annulus between the casing and the wall of the hole so that it can harden and fix the casing in place 334 STAB, TO: To insert the pin end of one pipe into the box end of another when making a connection STABBING BOARD: A movable platform 20 to 40 feet above the drill floor 335 Glossary of Marine Drilling terms Glossary of Marine Drilling terms on which a casing hand stands to guide one joint of casing into another in the rotary spare equipment and parts held onboard for the drilling and other departments STABILITY: The ability of a vessel to recover equilibrium when it is moved from the upright by external or internal forces The stability characteristics of semi-submersibles and monohulls are quite different but both are measured in terms of transverse and longitudinal metacentric height STORM AIR GAP: The distance between the sea surface and the underside of a semi-submersible when it is floating at its storm or survival draught STABILIZER: A downhole tool usedJor stiffening the bottom hole assembly and for keeping the bit central in the bottom of the hole and drilling vertically It looks like a drill collar but has short fins that contact the wall of the hole One or more stabilizers may be used in directional drilling when they are positioned to act as a fulcrum about which the assembly turns STRING UP, TO: To reeve the drilling line through the blocks of the hoist, securing one end at the dead line anchor and winding the other end onto the drawworks drum STACK: The name commonly used offshore for the blow-out preventer stack STORM DRAUGHT: Survival draught, q.v STUCK IN THE HOLE: The condition when drill pipe or some other tool or casing, etc is jammed in the hole after efforts have been made to pull it out STUMP TEST: A pressure test performed on the BOP stack when it is on the test stump in the cellar deck of a semi-submersible STACK, TO: To lay-up a drilling unit between contracts, usually because of lack of work 'Cold stacking' is mothballing, when equipment is demobilized and the crew taken off In 'warm stacking' a small maintenance crew keeps the rig ready for quick mobilization SUB: A short adaptor with different-threaded ends used to connect two items of downhole equipment which would otherwise not mate Short for 'sub-assembly' STAND: Three or sometimes two joints of pipe screwed together for easier and faster handling on the drill floor SUBMERSIBLE: A type of drilling platform which is designed to be floated to its location and then sunk so that its bottom rests on the sea-bed STANDBY BOAT: A ship whose duty is to stand by near the location of a manned offshore installation in case of an emergency necessitating evacuation, or in case of a man-overbaord situation or oil pollution The older standby boats in use in the North Sea are mainly converted trawlers, but newer vessels are purpose-built They carry fast inflatable rescue boats and radio equipment for liaising with helicopters and have emergency accommodation for the entire rig complement Under British regulations boats must remain within miles of the installation SUB-SEA ENGINEER: The rig crew-man on a floater responsible for the maintenance and running of the BOP stack and other items of sea-bed equipment such as guide bases, pin connector and wellhead He needs particularly a knowledge of hydraulics STAND PIPE: A tall, rigid pipe in the side of the derrick that carries drilling fluid up from the mud pumps and feeds it into the rotary hose that is suspended between its top and the swivel SURFACE LOCATION: The exact geographical position on which a drillinl unit is located This might be different to the target location to which the dril· ling bit is directed, especially if the well is a directional well STEP-OUT WELL: A well drilled close to a discovery well but in an unproven area, so that the boundaries of the producing formation can be determined SURVEY: A downhole examination normally carried out by wirellne tools to determine hole conditions such as bottom hole temperature and pressure or the direction and angle of inclination made by the hole STOREMAN: The rig crewman who maintains and distributes the stock of SURVIV AL DRAUGHT: The draught at which a semi-submersible rig is 336 SUPPLY BOAT: A vessel which carries oilfield equipment from shore bases to rigs on location It may be designed solely for supply work, or may be multi-purpose, doubling as an anchor-handler and/or tug 337 Glossary of Marine Drilling terms Glossary of Marine Drilling terms designed to be floated in severe weather conditions, such as a lOO-knotwind It is usually a compromise between having sufficient air gap and sufficient immersion of the pontoons and columns for adequate stability TENDER, TO: To make a bid for a drilling contract SURVIVAL SUIT: A special suit of thermally protective overalls worn by all helicopter passengers flying to offshore installations in cold-water areas such as the North Sea TEST STUMP: A short post fitted to the cellar deck on which the BOP stack can be pressure tested before use SWABBING: The action of creating a suction at the sides of a hole, either accidentally or on purpose If the bit or drill string is pulled out too quickly, swabbing can occur beneath it which may induce well fluids out of the formations, creating a kick TENSIONER, RISER: See riser tensioner THREAD PROTECTOR: Caps screwed on the ends of tubulars such as drill pipe, casing, etc., to protect their threads THRIBBLE: The American name for a 'treble', which is a stand of three single joints of drilling tubulars SWAMP BARGE: A type of flat-bottomed barge used for supporting a drilling rig and accommodation in swampy or shallow-water areas such as in West Africa and the US Gulf THRIBBLE BOARD: An American name for the monkeyboard which projects from the derrick at the height of a thribble, or a stand of three connected joints SWIVEL: The device which hangs from the hook below the travelling block that permits free rotation of the kelly whilst at the same time admitting drilling fluid to it from the rotary hose THROW THE CHAIN, TO: To throw the spinning chain up around the pin end of a joint of pipe, etc to obtain a purchase on it after it has been stabbed into the box of another joint The cathead then pulls the chain off the joint, tightening the connection -TTAG LINE: A line attached to a load being lifted by a crane so that the load can be safely manoeuvered when over the deck TARGET LOCATION: The exact geographical position of the target to which the drilling bit is directed as it drills In a deviated or directional hole this might be different to the surface location of the drilling rig T.D.: Total depth, q.v TELESCOPIC JOINT: An alternative name for the riser slip joint, q.v TEMPORARY GUIDE BASE: A heavy steel frame which is lowered to the sea bed at the start of an offshore drilling operation to serve as a foundation for subsequently deployed sub-sea equipment, to guide tools into the hole, and to provide an anchorage for the guide lines down which those tools and equipment are run Sometimes termed a 'drilling template' TENDER: A mobile barge which is moored alongside some types of fixed drilling platform to carry the drilling fluid circulation system, engines, drill pipe, accommodation, etc THRUSTERS: Propellers fitted on a vessel for manoeuvring purposes rather than for propulsion In addition to their main propellers, many drill ships have thrusters which are operated by the dynamic positioning system, while semi-submersibles usually have thrusters at the after end of their pontoons TIGHT HOLE: A security condition imposed by an operator when any information about the well operations is restricted in circulation When the well is a tight hole it may mean that it holds promise of being productive, but this is never certain TIGHT SPOT: A point in the hole at which the bit encounters difficulty drilling or wiping Tight spots are removed during a wiper trip, g.v In TONG LINE: A line attached to the handle of a tong for applying leverale when making a connection The back-up line connects the back-up (or make-up) tong to a fixed post, while the break-out line connects the breakout tong to a drawworks cathead TONGS: Large steel wrenches suspended from the derrick by wires that are used to tighten or loosen connections of drilling tubulars Two sets of tongs, 338 339 Glossary of Marine Drilling terms Glossary of Marine Drilling terms the back-up (or make-up) and break-out tongs, are used for drill pipe, and there may be sets of power tongs in addition Special tongs are used for casing TOOL JOINT: A short section of special steel pipe welded around each end of a joint of drill pipe to provide a means of connection and lifting The tool joint on the lower end, the 'pin', has a male thread which is inserted into the female thread at the upper end, the 'box', of the joint below when making a connection There are shoulders on the tool joints for the elevators to grip when lifting TOOLPUSHER, SENIOR: The supervisor of the drilling department on a rig, responsible to the rig (or drilling) superintendent for the day-to-day operations on the unit and for carrying out the operator's well programme as directed by the company man The 'pusher' may also be the Offshore Installation Manager on a British rig, but this depends on company policy On some American rigs the toolpusher may be known as the drilling foreman or the rig superintendent TORQUE: The turning moment of a force applied to a shaft, e.g a joint of drill pipe being made up to another The applied force in pounds multiplied by the lever length in feet gives the torque in foot-pounds TORQUE INDICA TOR: A gauge attached to the end of the make-up tong arm and with a remote read-out in the doghouse, so that the correct make-up torque can be applied to the tong TORQUE-UP, TO: To tighten a connection oftwo joints to the correct torque with the aid of tongs TOTAL DEPTH: The final depth attained by a well at the completion of drilling TOTAL VERTICAL DEPTH: See true vertical depth TOTCO: A downhole survey tool run down the inside of the drill string to determine the angle and direction of the bit's inclination from the vertical at any instant A small compass card is punched on the tool's arrival at the bit, and is read at the surface after the tool's withdrawal by the sand line TOUR: A work shift, usually of 12 hours duration on a rig Pronounced 'tower' in the oil industry, in the American fashion TOURPUSHER: An alternative name sometimes used for the junior or night toolpusher Pronounced 'towerpusher' TOWMASTER: The person (usually a master mariner) who takes charge of a rig-move from one location to another when towing vessels are employed He may be an employee of the drilling contractor or a specialist hired from a marine consultancy firm TRA.1'IJSIT:The passage of a rig from one location to another TRANSIT DRAUGHT: The draught of water drawn by a rig during her trasnit Normally this would be the lightest draught attainable, so that speed is maximised The waterline of a semi-submersible at transit draught is usually in the area of the top of the pontoons, i.e about 20 feet on a large unit TRAVELLING BLOCK: The lower, movable, block of the hoist, which is suspended by the drilling line from the upper, or crown block TREBLE: Three joints of drill pipe made up to make a stand of approximately 90 or 93 feet, for speed of handling TRIM: Strictly, the difference between the rig's forward draught and her after draught Usually, however, taken to mean the angle the rig is lying at with respect to the waterline TRIP GAS: Gas which comes up from the hole when a trip is being made Although it is often enough to activate the gas alarms it is rarely very much in volume TRIPPING: Making a round trip, q.v TRUE VERTICAL DEPTH: The depth of a hole measured in a vertical line from the surface to the bit, without taking account of any angle of deviation Measured depth (MD) may be considerably longer TUBING: Narrow-bore pipe which is run down through casing into a liner to serve as a channel for oil or gas after well tests have found evidence of hydrocarbons TUBULARS: Any oilfield pipe, e.g drill pipe, collars, casing or tubing TUGGER, AIR: See air tugger 340 341 Glossary of Marine Drilling terms Glossary of Marine Drilling terms TURBINE DRILLING: A method of rotary drilling in which the drill bit is rotated by a downhole drilling motor, or 'mud motor' , turbine or turbo-drill, just above it that is operated by the hydraulic force of the drilling fluid Sometimes called 'turbo-drilling' TRUBO-DRILL: A type of combined drill bit and downhole drilling motor used for turbine- or turbo-drilling T.V.D.: The usual abbreviation for true vertical depth or total vertical depth -uU.K.O.O.A.: The United Kingdom Offshore Operators Association, an organisation representing the interests of a group of about 40 operators of offshore licences for production of oil and gas from the UK Continental Shelf It provides a forum for discussion of technical and administrative matters and also consults with the UK government on these and other matters UKOOA has many technical committees aimed at ensuring the safety of offshore workers and the environmen t One of these prepares safety training guidelines UMBILICAL: A flexible hose providing services to an underwater installation or person A diver's umbilical connects him to a surface vessel or to a diving bell and contains pipes carrying air, hot water, gas, etc., while a pod umbilical carries the numerous control lines that actuate the BOP hydraulics ROVs are often operated by means of umbilicals UNDERREAMER: A downhole tool with rock bit cones on the ends of pivoting arms that can expand from the sides of the tool to open up a previously drilled hole This might be done to provide extra clearance for running casing so as to obtain adequate annular space for cementing, etc -v- ling equipment is dragged up the ramp and through the V-door to the drill floor VENT: When loading bulk cargo into 'P' tanks, the lines are first blown through by the supply boat's pumps to establish that they are clear, the sight of dust venting from an open overside valve proving this to the bargemaster and supply boat captain VENT LINE: A line fitted to the diverter at the top of the marine riser through which gas can be vented safely to atmosphere A deflector channels the gas to either the port or starboard side, whichever is downwind VERTICAL WELL: An undeviated well This is the type most frequently drilled from a mobile unit, while directional or deviated wells are commonly drilled from fixed platforms -wWAITING ON CEMENT: A period of several hours that must elapse after a cement job to allow the cement to set No downhole work is done during this time WAITING ON WEATHER: A period of downtime when drilling cannot continue because of the sea state High seas may cause excessive movement of the riser slip-joint, or of compensator or tensioner pistons WALKAROUND: The platform approximately half way up the derrick, at the height of the monkeyboard, which is normally enclosed by wind-resistant sheeting WASH OUT, TO: To erode a metal object such as a drilling tubular joint or a valve by the action of fluid pressure Washing out of damaged tool joints may occur through leakage equipment, WASH OVER, TO: To run a fishing tool, usually with a mill-type edge, over a fish so that the tool can be rotated to cut the fish free V.C.G.: The vertical centre of gravity of the rig, which must be at a certain distance below the metacentre for positive stability WATCH STANDER: The name used in some drilling companiel for the control room operator or the crewman whose job is to monitor the ballalt controls V-DOOR: An opening in the drill floor windwall on the side opposite the drawworks, from which a dragway ramp leads down to the pipe rack Dril- WATER TABLE: The frame near the top of the derrick in which the crown block is supported VARIABLE DECK LOAD: The weight of non-permanent stores, ballast, etc that a rig is able to carry when drilling 342 343 Glossary of Marine Drilling terms Glossary of Marine Drilling terms WATERTIGHT DOOR: A door fitted with securing devices which make it effectively watertight Mobile rigs have many of these and they should normally be kept closed except for access of hydrocarbons from a well These include acidizing and fracturing WELL STIMULATION VESSEL: A specially-designed ship which can be brought to a location to carry out well stimulation WATER TOWER: A retractable cylinder or frame containing deep well pumps and pipes that is lowered from a jack-up rig into the sea so that suction for engine cooling water and the fire main can be obtained WET TRIP: A 'trip' when mud flows out of the joints of drill pipe every time WEAR BUSHING: A ring-shaped device fitted inside the wellhead to protect the top of the casing from abrasion by the drill bit as it enteres or leaves the well WHIPSTOCK: A downhole tool used to deflect a bit out of its original course and set it in a desired direction towards a predetermined target They are used in directional drilling, in straightening crooked holes and in sidet- a connection is broken racking junk left in a hole WEATHER WINDOW: A period between spells of bad weather when a weather-dependent operation such as a rig-move or mooring operation might be carried out WILDCAT: An exploration well drilled in an unproved area, far from any WEEVIL: An American name for a new hand or 'green hand' on a rig; short for 'boll weevil' WILDCATTING: Drilling wildcat wells This is more likely to be the employment of a rig when the oil price is high, since only about one wildcat in forty, on worldwide average, becomes a discovery well WEIGHT INDICATOR: A gauge in the doghouse which tells the driller the weight suspended from the travelling block and the weight on the bit This information comes from a tension sensor at the deadline anchor WINDLASS: A large winch for winding anchor chain in or out Sometimes WELL: The completed hole made by the drill bit WINDW ALL: Sheeting erected round an exposed work area such as the drill existing producing well called an anchor winch floor or monkeyboard WELLBORE: The hole made by the drill bit Usually referred to as 'the hole' WELL COMPLETION: The final phase of operations after total depth has been reached, when the well is fitted with production equipment WELLHEAD: A cylindrical device placed at the top of the hole by a floater in which casing hangers are fitted and sealed and to which well control equipment can be attached during drilling and during subsequent production The BOP stack and, later, the Christmas tree are attached to the wellhead Jackup rigs and platforms install their wellheads on their decks WELL LOGGING: Any of various downhole methods used for the purpose of gaining information about formations drilled through In addition to mud logging, which is continuous, these include electric, radioactive and sonic logging techniques WELL STIMULATION: Any of several methods employed to increase flow WIPER TRIP: An operation to remove filter cake from the wall of the hole, made by running a rotating bit up and down the hole, going over any tight spots repeatedly until the wellbore is smooth It is normally done during drilling and before logging, running casing, etc to condition the hole WIRELINE: A long, narrow wire wound on a storage drum on the drillinl rig and used for well logging A variety of devices for measuring downhole conditions can be attached to the wireline Sometimes also the name liven to the drilling line on some American rigs W.O.C.: The normal abbreviation for 'waiting on cement', q.v WORKING TENSION: The tension to which anchor chains are initially slackened off to following pre-tensioning tests WORKOVER: An operation in which a rig is employed to restore or improve production from a completed well 345 344 Glossary of Marine Drilling terms WORK PERMIT: A written authorization to perform potentially hazardous work such as welding, flame cutting, electrical or overside work, issued by the OIM or person ultimately responsible for safety W.O.W.: Normal abbreviation for waiting on weather Printed and bound in Great Britain by Redwood Books, Trowbridge, Wiltshire ... that specialist drilling contractors this work for them, both on land and offshore Drilling contractors have the necessary men and skills, and a vast store of drilling experience, and between them... of many different types of rig that any operator, from a giant major to the smallest independent, can call on to tackle any type of drilling job Even the largest oil company, on the other hand,... usually the most important factor to any operator, and oil companies are normally prepared to pay whatever is necessary to obtain the right kind of reliable equipment and services to get the job done