IADC Drilling Manual Part 11 ppsx

P-59 International Association of Drilling Contractors Chapter P: Hole Deviation and Horizontal Drilling 11. Do not permit rig driller to drill through bridges encountered on trips in the hole without the directional supervi- sor being present. 12. Instruct the directional drilling supervisor in keeping drilling records your company will require. IV. Sub Surface Surveying A. Surveying Instruments 1. Single Shot A magnetic survey instrument consists of a compass, inclination unit, camera section, batteries and a time device. This instrument records drift angle and direction of the hole data on a single film disc. This instrument is used by the directional supervisor during drilling operations. 2. Multi-Shot A magnetic survey instrument that consists of the same elements as a single shot instrument except multiple readings of drift angle and direction are recorded on movie film. This instrument can be dropped in the hole and landed inside of a nonmagnetic collar to record many survey stations on trips in or out of the hole. 3. Gyroscope This type of survey instrument can record single or multi-shot surveys depending on the type of timing device and camera unit used. This instrument must have a known direction to set its pointer toward and all hole directions are referenced from the known direction. The instrument can be used inside of a cased hole because it is not affected by magnetized pipe or influenced by formations that would affect a magnetic compass. B. Non-Magnetic Drill Collars The maximum length of non-magnetic drill collar required can be determined by referring to Figures P2-5, Figure P2-6 and Figure P2-7. P-63 International Association of Drilling Contractors Chapter P: Hole Deviation and Horizontal Drilling Figure P2-4 Zone Selection Map P-64 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition Magnets are sometimes used in non-magnetic drill collars by the Directional Driller for orientation only, and should be replaced with brass pugs when they are not required for orientation. C. Surveying Procedure All Surveys should be reported as located at the angle unit depth. Report all acceptable surveys (exclude orienta- tion surveys). The IADC API drilling report is the place to record each bottom assembly used. 1. Location of Baffle Plate The baffle plate for the survey instrument should be located at the bottom of the bottom non-magnetic drill collar. 2. Declination The difference between true north and magnetic north is declination. The declination varies around the world as shown on the example Isogonic Chart attached, Figure 2-8. P-66 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition Notes for Figure P2-8 Isogonic Chart Magnetic declination (also called "variation of the compass") is here shown as of the beginning of 1975 by means of isogonic lines, i.e. lines of equal declination. These lines are solid in the area where the compass points east of true north, and broken in the area where it points west of true north. The lines are drawn to show a relatively smooth distribution. The irregularities remaining in the lines, particularly the local anomalies, rather than as a close representation of the declination, If Disc Reading EAST DECLINATION WEST DECLINATION (Add in Azimuth) (Subtract in Azimuth) NE ADD to reading SUBTRACT from reading SE SUBTRACT from reading ADD to reading SW ADD to reading SUBTRACT from reading NW SUBTRACT from reading ADD to reading Magnetic declination (also called "variation of the compass") is here shown as of the beginning of 1975 by means of isogonic lines, i.e. lines of equal declination. These lines are solid in the area where the compass points east of true north, and broken in the area where it points west of true north. The lines are drawn to show a relatively smooth distribution. The irregularities remaining in the lines, particularly the local anomalies, rather than as a close representation of the declination, If Disc Reading EAST DECLINATION WEST DECLINATION (Add in Azimuth) (Subtract in Azimuth) NE ADD to reading SUBTRACT from reading SE SUBTRACT from reading ADD to reading SW ADD to reading SUBTRACT from reading NW SUBTRACT from reading ADD to reading There is an annual variation in declination. The chart used must be up to date. The declination can be corrected to true north or to grid north. The correction will be made to true north unless stated otherwise in the drilling program or directional plat. 3. Calculation of Surveys The radius of curvature method is the most accurate way to calculate a directional survey. This is usually done by means of a computer or programmable pocket calculator. However, the balanced tangential or vector averaging method approaches the accuracy of the radius of curvature method and is usually used by directional drilling supervisors in the field. V. Deflection Tools A. Downhole Motors The downhole mud motor has replaced the Whipstock as the primary tool to deviate the direction of a wellbore. The mud motor function is to rotate the bit when a bent sub assembly is used. This eliminates drill string rotation and the well bore is deviated in the direction of the oriented bent sub. The deviation assembly is made up of a nonmagnetic collar, a bent sub, a mud motor and the drilling bit. The downhole mud motor is either a positive P-67 International Association of Drilling Contractors Chapter P: Hole Deviation and Horizontal Drilling displacement type or a turbine. The motor size is determined by the size of the bit being run. Performance charac- teristics are given in Table P2-1 and Table P2-2. P-70 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition Dog-leg expectancy is a function of the assembly geometry and not the type of mud motor. You would expect to develop the same rate of hole deviation change if the bent sub angle, motor O.D. and length and average weight on bit are the same regardless of the type of mud motor. When a turbine is used, a screen should be placed between the kelly and the drill pipe to insure against foreign material being pumped through the turbine and causing a motor failure. If the mud system is using lost circulation material, the screen procedure is not feasible and a turbine should not be used. 2. Positive Displacement Mud Motor The positive displacement mud motor runs at lower RPM for a given mud volume than the turbine. Large diameter tricone bits with high torque requirements are easily handled. Tool operating data is given in Table P2-1. The positive displacement motor torque varies in a direct ratio to the pressure differential across the motor. This provides surface indication on the mud pump gauge. Increasing bit torque up to stall conditions can be monitored. Lost circulation material in the mud is normally handled by positive displacement motors without problems. B. Whipstocks The removable whipstock is a reliable deflection tool that is usually used when jetting or when downhole motors cannot be used. It is a cylindrical steel casting, five to thirteen feet long, with a ring at the top, a concave inclined groove formed on one side and a chisel point bottom. The ring at the top is smaller than the bit and provides the means of transporting the whipstock in and out of the hole. The chisel bottom holds the whipstock stationary when it is set, and the indented groove, (usually 3 degrees) guides the bit to a new course. There are two types of whipstocks: 1) the bottom circulating in Figure 2-9a and 2) the standard or conventional shown in Figure 2-9b. Figure P2-9 Whipstocks The circulating whipstock differs from the standard whipstock, in that there is a control sub immediately above the bit that prevents the flow of circulating fluid through the bit and deflects it through a hollow shear pin used to pin the whipstock to the drill pipe assembly. The flow of fluid passes through the shear pin and down to the bottom of the whipstock via a bored circulating channel in the back of the whipstock. The fluid then flows out the bottom of P-71 International Association of Drilling Contractors Chapter P: Hole Deviation and Horizontal Drilling the whipstock. This permits the bridges in the hole to be washed through, and fill up on the bottom of the hole to be circulated clean. Prior to setting the whipstock, a ball is dropped through the drill pipe and seated in the control sub. The drilling fluid is then diverted from the bottom of the whipstock and established through the bit. The whipstock can then be set and drilling commenced. A 15' - 20' rat hole is usually drilled below the whipstock setting point. The diameter of this hole is smaller than the open hole, and must be reamed out to the full hole size by means of a hole opener. Therefore, setting a whipstock is slower than other deflection tool methods because more trip time is needed to set and ream the rat hole out to full gauge. A combination universal knuckle joint and short drill collar may be run in conjunction with the whipstock when extreme angles are required to sidetrack an enlarged hole. C. Jetting Holes in soft formations are usually deviated by using a bit which has all but one of the nozzles closed off, or substantially reduced in size. One 3/4" or 5/8" nozzle and two 1/4" nozzles are popular sizes frequently used. To use, an angle building assembly (see Fig. 10) and jet bit designed for deviation jetting is run in the hole and oriented in the desired direction. Figure P2-10 Jetting for Directional Control Notes for Figure P2-10 A. Washing action by large jet (left) B. When rotation is started stabilizer smooths out dog-leg on high side (middle) P-72 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition C. After initial deflection has been accomplished, stabilizer acts as a fulcrum for continuing the hole curvature (right) A high rate of circulation is established and the bit with weight applied is set on bottom. Fluid circulating through large nozzle permits the hole to erode on one side. The drilling assembly is spudded to force the bit to follow the jetted hole. After two to four feet of jetted hole is obtained drilling is commenced. After jetting, a single shot survey is run to determine the dog-leg severity of the hole. Reaming may be necessary if the dog-leg obtained is more than desired. D. The Rebel Tool The Rebel Tool is designed to prevent and correct lateral drift. See Figure P2-11 Figure P2-11 Rebel Tool Without orientation, the tool counteracts the bit's tendency to walk either left or right. P-73 International Association of Drilling Contractors Chapter P: Hole Deviation and Horizontal Drilling With a Rebel Tool, Drilling can continue under normal or near-normal weight loads, rotary speeds and pump pressures. The drift angle can be maintained as effectively with the Rebel Tool as with ordinary drill collar and stabilizer drilling assemblies. Mounted just above the bit, the Rebel Tool imparts a lateral shove to the sidewall by means of two opposing paddles. The paddles are rigidly secured to a common shaft which is free to turn within a groove along the tool's body. As it rotates to the low side of a slant hole, the top paddle is forced by weight into a recess in the body of the tool. This extends the bottom paddle to shove against the sidewall in the direction desired down near the bit, where the effect is greatest. In cases where the Rebel Tool is used to correct lateral drift that already has occurred, slight overcompensation is recommended before pulling the tool to resume normal drilling. Several hundred feet of depth should be allowed to effect the desired walk. To walk bit left: with left paddles (seen here in cross section from above, the bottom paddle kicks bit to the left when extended by weight on its opposing member VI. Orientation Of Deflection Tools Deflection tools may be oriented by many means, the most common of which are: A. Mule Shoe A lug inside of a special sub is aligned with the bend or face of a deflection tool that is run into the hole with the deflection tool. A single-shot instrument is run into the hole inside of a protective case that has a stinger on the bottom that is helixed in a curving manner so that when helex curving engages the orientation lug inside of the special sub, the instrument is rotated so that the key slot on the stinger sets exactly on the lug. A single-shot survey is taken so that the direction of the key slot can be determined. Orientation of the tool can then be completed. B. Direct Method North and South magnets are placed inside of a nonmagnetic drill collar in a position to align with a needle located inside of the single-shot instrument. The compass unit is below the magnets and is not affected by the magnets. The needle pointing to the magnets is superimposed on a directional survey film disc. When a survey is taken, the direction of the deflection tool can then be found and the tool set. P-74 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition C. Surface Readout Figure P2-12 Steering Tool [...]... Critical Dogleg severity curve that could be calculated for drilling conditions expected to exist in a typical 12,000 foot well P-82 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition P-3 Horizontal Drilling The following is a series of five articles in the 1988/89 Drilling Contractor Magazine addressing horizontal drilling A Planning (Authors Denny Kerr And Albert Odell)... replaced with a drilling assembly as shown in Figure P2-13 Figure P2-13 Maximum Angle Building Assemblies However, if jetting has been the method of initial control, the assembly shown probably has been the one used in conjunction with the orientable jet bit In this event, drilling continues without requiring a trip International Association of Drilling Contractors P-75 IADC Drilling Manual - Eleventh... computer yet complex enough to provide an accurate prediction of BHA trajectory P-90 International Association of Drilling Contractors P-91 Chapter P: Hole Deviation and Horizontal Drilling Figure P3-6A Trajectory Prediction Worksheet International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition The following parameters are taken into account: hole size and angle, formation dip,... takes place, the less distance is available below the kick-off point for suspended members to produce a tensile load while drilling With medium-radius wells, there is typically no tensile load while drilling International Association of Drilling Contractors P-101 IADC Drilling Manual - Eleventh Edition It is important to remember that there are collars stacked in the vertical section of the hole above... section plot of the actual wellbore P-106 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition Figure P3-3E What the Records Show TABLE P3-1E BHA Used in Horizontal Extension TABLE P3-2E Steerable BHA Used P-108 International Association of Drilling Contractors Chapter P: Hole Deviation and Horizontal Drilling TABLE P3-3E Rotating BHA Builds from 85 to 93.5 degrees This... in drill collar assembly or replaced with full gauge tools Additional information on the subject of stabilization is contained in the Straight Hole Section of the manual International Association of Drilling Contractors P-77 IADC Drilling Manual - Eleventh Edition VIII Dog-leg Severities A Drill Pipe Fatigue Changes in hole curvature are often referred to as dog-legs The severity of a dog-leg is determined... kicked-off for a second time at the end of the section The ability to accurately predict the trajectory of a given BHA can provide considerable cost savings International Association of Drilling Contractors P-89 IADC Drilling Manual - Eleventh Edition 5 Performance Predictions It was mentioned earlier that build rate is not the only determinant of tool configuration (i.e., single vs double bend) It has been... dog-leg = proposed TD - depth of dog-leg - DC length = 18,000 ft - 3000 ft - 1000 ft = 14,000 ft (D) Maximum safe dog-leg limit = 3.2° Complements of Drilco International Association of Drilling Contractors P-81 IADC Drilling Manual - Eleventh Edition Figure P2-20 Maximum Safe Dog-Leg Limits, S-135 DP, Notes for Fig P2-19 - EXAMPLE Example: (dog-leg at 3,000 ft.) (A) proposed mud weight at TD 18,000 ft =... re-inspected 5 Case Study The following case study illustrates a typical drill stem for a medium-radius well with an extended horizontal section (Figure P3-2B) International Association of Drilling Contractors P-93 IADC Drilling Manual - Eleventh Edition TABLE P3-2B Tensile Yield Strength - API Class 2 Further down the drill stem, as incremental pick-up load decreases, Schedule 95 pipe may be used and drill... no reason from a drill stem design standpoint that the horizontal sections in medium-radius wells cannot be extended to at least 5,000 ft using standard International Association of Drilling Contractors P-97 IADC Drilling Manual - Eleventh Edition tubulars Both target TVD and displacement from the original wellbore or surface location can have major effects on the basic build profile Lease line restrictions . Association of Drilling Contractors Chapter P: Hole Deviation and Horizontal Drilling Figure P2-4 Zone Selection Map P-64 International Association of Drilling Contractors IADC Drilling Manual - Eleventh. this event, drilling continues without requiring a trip. P-76 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition Building angle with a limber drilling assembly. calculated for drilling conditions expected to exist in a typical 12,000 foot well. P-84 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition P-3 Horizontal Drilling The