IADC Drilling Manual Part 13 pot

T-5 International Association of Drilling Contractors Chapter T: Cementing Type IV for use when low heat of hydration is require. Type IV cement is not commonly used in oil wells. Type V for use when high sulfate resistance is require. Type V cement is not commonly used in oil wells. C. API Specifications With the advent of drilling of deeper oil wells it became apparent that the ASTM classification for cement would not meet the conditions necessary for the cementing of these deeper wells. This necessitated the formulation of an API (American Petroleum Institute) Specification for Oil-Well Cements. The are classified in API Spec 10 as follows: A well cement which has been manufactured and supplied according to this specification may be mixed and placed in the field using water ratios or additives at the user's discretion. It is not intended that manufacturing compli- ance with this specification be based on such field conditions. Classes and Grades. Well cement shall be specified in the following Classes (A, B, C, D, E, F, G and H) and Grades (O, MSR and HSR). Class A This product obtained by grinding Portland cement clinker, consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an interground addition. At the option of the manufacturer, processing additions* may be used in the manufacture of the cement, provided such materials in the amounts used have been shown to meet the requirements of ASTM C 465. This product is intended for use when special properties are not required. Available only in ordinary (O) Grade (similar to ASTM C 150, Type I). Class B The product obtained by grinding Portland cement clinker, consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an interground addition. At the option of the manufacturer, processing additions* may be used in the manufacture of the cement, provided such materials in the amounts used have been shown to meet the requirements of ASTM C 465. This product is intended for use when conditions require moderate or high sulfate-resistance. Available in both moderate (MSR) and high sulfate- resistance (HSR) Grades (similar to ASTM C 150, Type II). Class C The product obtained by grinding Portland cement clinker, consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as in interground addition. At the option of the manufacturer, processing additions* may be used in the manufacture of the cement, provided such materials in the amounts used have been shown to meet the requirements of ASTM C 465. This product is intended for use when conditions require early strength. Available in ordinary (O), moderate sulfate-resistance (MSR) and high sulfate- resistant (HSR) Grades (similar to ASTM C 150, Type III). Class D The product obtained by grinding Portland cement clinker, consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an interground addition. At the option of the manufacturer, processing additions* may be used in the manufacture of the cement, provided such materials in the amounts used have shown to meet the requirements of ASTM C 465. Further, at the option of the manufacturer, T-6 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition suitable set modifying agents* may be interground or blended during manufacture. This product is intended for use under conditions of high temperatures and pressures. Available in moderate sulfate-resistant (MSR) and high sulfate-resistant (HSR) Grades. Class E The product obtained by grinding Portland cement clinker, consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an interground addition. At the option of the manufacturer, processing additions* may be used in the manufacture of the cement, provided such materials in the amounts used have been shown to meet the requirements of ASTM C 465. Further, at the option of the manufac- turer, suitable set modifying agents* may be interground or blended during manufacture. This product is intended for use under conditions of high temperatures and high pressures. Available in moderate sulfate-resistance (MSR) and high sulfate-resistant (HRS) Grades. Class F The product obtained by grinding Portland cement clinker, consisting of essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an interground addition. At the option of the manufacturer, processing additions* may be used in the manufacture of the cement, provided such materials in the amounts used have been shown to meet the requirements of ASTM C 465. Further, at the option of the manufac- turer, suitable set-modifying agents* may be interground or blended during manufacture. This product is intended for use under conditions of extremely high temperatures and pressures. Available in moderate sulfate-resistant (MSR) and high sulfate-resistant (MSR) Grades. Class G The product obtained by grinding Portland cement clinker, consisting essentially of hydraulic calcium silicates usually containing one or more of the forms of calcium sulfate as an interground addition. No additions other than calcium sulfate or water, or both, shall be interground or blended with clinker during manufacture of Class G well cement. This product is intended for use as a basic well cement. Available in moderate sulfate-resistant (MSR) and high sulfate-resistant (HRS) Grades. Class H The product obtained by grinding Portland cement clinker, consisting essentially of hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an interground addition. No additions other than calcium sulfate or water, or both, shall be interground or blended with the clinker during manufacture of Class H well cement. This product is intended for use as a basic well cement. Available in moderate sulfate-resistant (MSR) and high sulfate-resistant (HSR) Grades. The placement of any cement composition depends primarily on temperature rather than depth. The API testing schedules for standardization purposes have been developed after many years of study and industry cooperation. This is an average and extrapolative data should be used with caution as it may not meet your well conditions. Instrumentation is available to measure bottom hole circulating temperature very easily in today's field operations before each cement job. These schedules in Table T1-1 represent average temperatures at various depths along the Gulf Coast and may not correspond to temperatures at the same depths in other areas. T-7 International Association of Drilling Contractors Chapter T: Cementing Table T1-1 Basis For API Well-Simulation Test Schedules Values in parenthesis represent the time for the first sack of cement to reach bottom hole conditions. D. Testing and Blending In recent years, major advancements have been made in oil well cements, admixtures for cements and equipment for testing cements. The development of the Pan American thickening time tester makes possible the testing of oil well cements under simulated temperature and pressure conditions encountered in actual well operations. See Figure T1-1. Figure T1-1. The Pressure-Temperature Thickening Time Tester It should be used with samples of actual cement and mixing water where placement conditions are critical. Tests such as these give accurate data as to the thickening time of a cement under prescribed well conditions. T-8 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition The cements used in oil wells are usually referred to as portland, high early strength and retarded. However, with the tremendous number of admixtures available, the cementing of an oil well has developed into what may be regarded as a chemical service. Cementing compositions are now being tailormade for specific well conditions. The inauguration of bulk cement blends are then delivered to the well site in specially designed carriers where cementing units complete the job of mixing and pumping the cement into the well. E. Yield of Cements Due to the ease of making calculations, it is becoming more common to estimate the amount of cement required in terms of cubic .feet of cement in cementing oil wells. Overseas operations often require the quantity of cement reported in cubic meters and the weight of the slurry in specific gravity, instead of pounds per gallon or pounds per cubic foot. This change has been due to the fact that more cement is brought to the job in bulk trucks rather than sacks. Table T1-2 gives the relations of the yield of cement slurry in cubic feet per standard sack and cubic meters per standard sack. Table T1-2 Yield of Cements Density is expressed in pounds per gallon, pounds per cubic foot and specific gravity. T-9 International Association of Drilling Contractors Chapter T: Cementing T2. Casing Strings I. Introduction A. General Types of Casing and Reasons for Cementing 1. Conductor casing or pipe: set to prevent caving around the mouth of the bore and conduct drilling fluid to a sufficient height while drilling surface hole. 2. Surface casing or pipe: set to protect fresh water zones, to guard against possible cave-in of the near-surface formations and to provide a position for the initial well control devices. 3. Intermediate or protection string: run inside the surface pipe to protect the hole for various reasons. One or more such strings may be set. 4. Oil string: set to isolate and protect the prospective producing formations; to test for production and for purposes of completing the well as a producer. With respect to the above general types of easing, it is only when it is cemented and a strong tight seal is formed between the casing and wall of the hole, does casing do the job for which it is intended. B. Reasons for Cementing The cementing of oilwells accomplishes the following: 1. Bonds the casing to the formation, thus supporting and strengthening it. 2. Protects the oil producing zones. 3. Seals against contamination to fresh water zones that may be used for domestic supply and protects other possibly useful strata such as coal, potash, and other oil and gas zones not being used. 4. Helps prevent blowouts from high pressure zones behind the casing. 5. Protects the casing from excluded corrosive waters and lowers electrolytic currents. 6. Seals off "lost circulations" zones and other troublesome formations in order to drill ahead. 7. Protects surface pipe and intermediate casing strings while drilling additional hole. Uncemented pipe is severely shock loaded. 8. Prevents the vertical migration of formation fluids between the casing and hole wall. 9. Provides a base for fracturing, squeeze cementing and future workover during the life of the well. C. Casing Running Equipment and Accessories The surface equipment usually required for running of casing in a well consists of a spinning line, or power tongs, conventional power tongs, special slips, or spiders. The subsurface equipment attached to the casing are centraliz- ers, casing shoe or float shoe and/or float collar, and wall cleaners. The type of each piece of subsurface equip- ment varies with the requirements peculiar to the well to be cemented, the type and design of the casing string used. The subsurface equipment may be described briefly as: 1. The guide shoe usually used with a float collar in the casing string; it is placed on the bottom joint of casing and has a rounded nose to prevent digging into the side of the hole wall. 2. Float shoes can be divided into two classifications: T-10 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition a. Seal type shoe that allows the casing to be floated down filling the casing at the top from a hose connected to the standpipe. b. The differential type shoe that allows the drilling fluid to enter the casing at the bottom as it is being lowered but only allows the fluid level in the easing to reach 91% of the fluid level in the annulus. Designed to eliminate or reduce high pressure surges against the formation as casing is lowered. 3. The float collar is usually made up in the easing string about one joint above the casing shoe essentially serves the same purpose as the float shoe but for different application of the cement. 4. Centralizers are attached to the casing to center the casing in the bore of the hole thus securing a uniform deposit of cement around the casing. 5. Scratchers or wall cleaners are attached to the casing to remove the mud cake from the hole wall thus assuring a better bond between the wall and the cement. Wall cleaners are generally cable or spring wire devices and are of two types: a. The rotating wall cleaner which removes the mud cake by simply rotating the casing while circulating the drilling fluid. Often preferred because it does not require the movement of the casing once it is set at the desired depth. b. The reciprocating wall cleaner which requires the raising and lowering of the entire casing string i.e.,reciprocation, to remove the mud cake. 6. Cement Baskets attached to casing are commonly used to isolate the troublesome zones or coal, mineral, or potable water strata above the production zones. A packer is set inside the casing opposite the basket on the outside. The casing is perforated at the point and cement is squeezed through the perforations into the basket. As the weight of the cement builds up, the basket is forced against the hole wall to prevent the heavier cement slurry from slipping down in the annulus. D. Types of Cementing Jobs Most cementing jobs fall under three general classifications: 1. cementing through pipe and casing; 2. cementing through drill pipe; 3. cementing through tubing. 1. Cementing through pipe and casing. a. Conductor pipe cementing job. b. Surface casing cementing job. c. Protection or intermediate string job single stage. d. Protection or intermediate string job two stage. 1) Placing two batches of cement with continuous cementing operations overlapping; 2) Bell hole job with two stages: a) Gel, water or petroleum base compounds placed through top stage, this string being placed through a very large string casing to allow for shilling of formations; modifications of this same job being used to combat corrosion, then; b) Bottom stage is cemented. e. Protection string job three stage. T-11 International Association of Drilling Contractors Chapter T: Cementing f. Production string job single stage. g. Production string job two stage. h. Production string job three stage. i. Split pipe or split easing job. 1) Locating split or leak in casing using plug method and measuring line. 2) Locating split or leak using hook wall packer. j. Liner or short string job. k. Bull head squeeze job. 2. Cementing through drill pipe or tubing. a. Placing cementitious materials for lost circulation problems. b. Open hole plug back job. c. Straight plug back job. d. Bradenhead squeeze job. 3. Cementing through tubing and, in some cases, drill pipe. a. Retainer (drillable) squeeze job. b. Packer (retrievable) squeeze job. c. Scabbing methods 1) Placing cement through perforated liner using straddle took, dump bailer, open ended tubing or drill pipe, down swab assumable, retainer and drillable tailpipe. 2) Drillable sleeve cemented in place. d. Liner or short string squeeze job using bradenhead. e. Liner or short string squeeze job using packer type setting tool. 4. Combination of various jobs and new developments. a. Top outside job, between easing or between casing and hole, using tubing or small diameter pipe. b. Cementing annulus between string through casing head surface connection. c. Combination job. 1) Two sections of casing bottom section liner job. 2) Top section single stage job using special Tool to joint two strings together. d. Full hole job (in some areas called combination string), placing cement through tool above a liner which is the same size as the casing. e. Permanent-type completions (PWC). f. Concentric tubing. g. Multiple tubingless completions. T-12 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition h. Casing patch. i. Wireline squeeze jobs. II. Plug Back Cementing A. Reasons for Placing a Cement Plug Figure T2-1: There are several reasons for setting a cement plug 1. ZONE ISOLATION In a well with two or more producing zones, it is sometimes beneficial to abandon a depleted or unprofitable producing zone by placing a permanent cement plug above it, thus helping to prevent possible production loss into, or fluid migration from, the lower interval. 2. LOST CIRCULATION CONTROL During the drilling operation, if mud circulation is lost, it is sometimes possible to restore circulation by spotting a cement plug across the thief zone and drilling back through the plug. Generally, this operation is less expensive than a squeeze cementing job. 3. DIRECTIONAL DRILLING In an operation designed to sidetrack the hole around a non-retrievable fish, such as a broken drill string which has become stuck in the hole, it is necessary to place a cement plug at a specific depth to help support the whipstock for directing the bit into the desired area. Another example of a controlled change in the drilling direction to help reach a specific target area is in shoreline drilling operations for offshore production. T-13 International Association of Drilling Contractors Chapter T: Cementing 4. FORMATION TESTING A cement plug is sometimes placed below a zone to be tested which is considerable distance from the bottom, and a straddle packer with a side wall anchor or a bridge plug is not possible or practical. 5. ABANDONMENT To seal off a dry hole or depleted well, a cement plug placed at the required depth, helps prevent zone communica- tion and any migration of fluids that might infiltrate underground fresh water sources or cause undesirable surface conditions. B. Common Plug Back Techniques 1. THE BALANCE METHOD Using this technique, Figure T2-2, the desired quantity of cement slurry is usually placed in the drill pipe or tubing and displaced from the bottom of the string until the level of cement outside is equal to that inside the string. Figure T2-2: Balance plug method The pipe or tubing is then pulled slowly from the slurry, leaving the plug in place. See T-3 Balancing a Plug for calculations. ADVANTAGES: This method is simple and requires no special equipment other than a cementing service unit. OTHER CONSIDERATIONS: A) When it is difficult to establish the top of a cement plug, it may be necessary for the well owner to run an excess of cement, then pull the running-in string to the desired plug top and reverse out the excess cement above that point. A loss of fluid to the formation below this point may cause a movement in the plug. B) Contamination of the cement with mud is possible, especially when using small volumes of cement. C) If the drilling mud is of low viscosity it may be necessary to place a viscous pill to keep the cement slurry from falling downhole. T-14 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition 2. THE DUMP BAILER METHOD This technique is usually employed at shallow depths, but with the availability of new materials it has been used to depths of over 20,000 feet. The dump bailer, containing a measured quantity of cement, is lowered on a wire line. A Limit Plug, Cement Basket, permanent type bridge plug, or gravel pack is usually placed below the desired plugging location. The bailer is dumped and raised to place cement above the plug or basket, Figure T2-3. Figure T2-3: Dump bailer method Method may include limit plug* (b), or a basket (c). ADVANTAGES: A) Since the tool is run on wire line, depth of plug is easily controlled. B) The cost of a dump bailer is usually low. OTHER CONSIDERATIONS: A) Not as readily adaptable for setting deep plugs. B) Mud Contamination of cement may occur unless the well operator circulates the hole prior to dumping. C) Limited on the quantity of slurry that can be placed per run and initial set must be attained before the next run can me made and the bailer dumped. 3. THE TWO PLUG METHOD This method, Figure T2-4, involves running top and bottom cementing plugs to isolate the cement from the well displacement fluids (similar to standard primary cementing practices). [...]... International Association of Drilling Contractors T-29 Chapter U: SCR Systems Chapter U Electric Drilling Rigs International Association of Drilling Contractors U-1 IADC Drilling Manual - Eleventh Edition Table of Contents - Chapter U Electric Drilling Rigs U-1 Silicon Controlled Rectifier Systems U-4 1 Introduction U-4 A DC/DC and SCR Systems U-4 B DC Drilling Motors ... U-24 U-2 International Association of Drilling Contractors Chapter U: SCR Systems CHAPTER U SCR Systems The IADC Drilling Manual is a series of reference guides for use in field operations covering a variety of subjects related to drilling operations The contents of this (these) volume (s) are assembled by a wide range of members of the drilling industry interested in providing information... efficiency and enhancing proper placement of the propping agent International Association of Drilling Contractors T-27 IADC Drilling Manual - Eleventh Edition Heavy-weight Additives Added to different type cements to increase density of slurries in deep wells where it is desired to have the weight of the cement near that of drilling mud at the time of cementing for the control of high pressure oil and gas... demonstrated by full scale laboratory testing and field experience to be important in horizontal cementing International Association of Drilling Contractors T-21 IADC Drilling Manual - Eleventh Edition T3 Balancing A Plug I Balancing A Plug A General Considerations When a cement plug is spotted on bottom through tubing or drill pipe, the tubing or drill pipe is run to bottom The cement is pumped down the tubing... follows: Lift = Pipe L x [(Hd of cmt/ft) - (Hd water/ft)] x (Area Pipe ID) Note: some manuals call Hd of fluid/ft the Fluid Gradient and express it in psi/ft If such lift exceeds or approaches the pipe weight, then the pipe should be anchored in some manner International Association of Drilling Contractors T-25 IADC Drilling Manual - Eleventh Edition T-4 Estimating Cement Required For Various Cementing Jobs... comes from the driller's console and represents a desired speed for a drilling load (mud pump strokes per minute or rotary table rpm) By determining when an SCR turns on in an electrical cycle the output DC voltage can be varied from 0 to 750 volts DC See Figure U2-3 U-10 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition B3d 600 to 480 Volt Distribution Transformer... little added weight to move it out of the tubing The added cement left in the tubing by under displacement will generally give the needed additional weight International Association of Drilling Contractors T-23 IADC Drilling Manual - Eleventh Edition II Calculating Fillup It is necessary in all cementing operations, except squeeze work, to have a pretty good idea of the fillup to be obtained from a certain... Power Generation U-6 A3 AC Switchgear U-7 B AC/DC Conversion U-8 U-3 DC/DC Power Systems U -13 A Introduction U -13 B Controls U -13 C Braking U -13 D System Protection U-14 E Driller's Console U-14 U-4 Maintenance U-15 General U-15... hesitation method, Figure T2-7, involves the placement of cement in a single stage, but divided the placement into alternate pumping and waiting periods T-18 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition Pressure is held momentarily on the formation to verify static conditions and then released to determine if cement will stay in place The excess slurry above... positive on the DC or load side of the bridge) Some SCR systems have 3 current limiting power fuses (one per phase on the AC or line side of the bridge) International Association of Drilling Contractors U-9 IADC Drilling Manual - Eleventh Edition All power fuses have the task of limiting damage to the SCR's in a fault condition FIGURE U2-2: Power Circuit Diagram B2c SCR Heat Sink Assemblies Since SCR's . cementing. T-22 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition T3. Balancing A Plug I. Balancing A Plug A. General Considerations When a cement plug is spotted on bottom through. of a cement under prescribed well conditions. T-8 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition The cements used in oil wells are usually referred to. shoes can be divided into two classifications: T-10 International Association of Drilling Contractors IADC Drilling Manual - Eleventh Edition a. Seal type shoe that allows the casing to be floated