US20220316287A1 - Method of supplying cement slurry and method of drilling or cementing of well using the same - Google Patents
Method of supplying cement slurry and method of drilling or cementing of well using the same Download PDFInfo
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- US20220316287A1 US20220316287A1 US17/616,017 US201917616017A US2022316287A1 US 20220316287 A1 US20220316287 A1 US 20220316287A1 US 201917616017 A US201917616017 A US 201917616017A US 2022316287 A1 US2022316287 A1 US 2022316287A1
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- United States
- Prior art keywords
- cement slurry
- hole
- capsule
- drilling
- supplying
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- Abandoned
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- 239000004568 cement Substances 0.000 title claims abstract description 183
- 239000002002 slurry Substances 0.000 title claims abstract description 178
- 238000000034 method Methods 0.000 title claims abstract description 50
- 238000005553 drilling Methods 0.000 title claims description 60
- 239000002775 capsule Substances 0.000 claims abstract description 122
- 239000000155 melt Substances 0.000 claims abstract description 9
- 239000012530 fluid Substances 0.000 claims description 8
- 238000002347 injection Methods 0.000 claims description 8
- 239000007924 injection Substances 0.000 claims description 8
- 238000002844 melting Methods 0.000 claims description 8
- 230000008018 melting Effects 0.000 claims description 8
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 7
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 5
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical group [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 4
- 239000001110 calcium chloride Substances 0.000 claims description 4
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 4
- 230000007547 defect Effects 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 238000011144 upstream manufacturing Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 15
- 230000008569 process Effects 0.000 description 13
- 239000000463 material Substances 0.000 description 8
- 238000005520 cutting process Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 125000006850 spacer group Chemical group 0.000 description 5
- 239000003921 oil Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 239000000440 bentonite Substances 0.000 description 2
- 229910000278 bentonite Inorganic materials 0.000 description 2
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000011440 grout Substances 0.000 description 2
- 230000002706 hydrostatic effect Effects 0.000 description 2
- 150000002484 inorganic compounds Chemical class 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 240000007049 Juglans regia Species 0.000 description 1
- 235000009496 Juglans regia Nutrition 0.000 description 1
- -1 KNOB) Chemical compound 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- 239000007832 Na2SO4 Substances 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-N Nitrous acid Chemical compound ON=O IOVCWXUNBOPUCH-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- ZMZDMBWJUHKJPS-UHFFFAOYSA-M Thiocyanate anion Chemical compound [S-]C#N ZMZDMBWJUHKJPS-UHFFFAOYSA-M 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000004645 aluminates Chemical class 0.000 description 1
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 description 1
- 229910021502 aluminium hydroxide Inorganic materials 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 229910052925 anhydrite Inorganic materials 0.000 description 1
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 235000008504 concentrate Nutrition 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 150000002258 gallium Chemical class 0.000 description 1
- 229910001679 gibbsite Inorganic materials 0.000 description 1
- ZMZDMBWJUHKJPS-UHFFFAOYSA-N hydrogen thiocyanate Natural products SC#N ZMZDMBWJUHKJPS-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 235000020429 malt syrup Nutrition 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000008267 milk Substances 0.000 description 1
- 235000013336 milk Nutrition 0.000 description 1
- 210000004080 milk Anatomy 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 229920005615 natural polymer Polymers 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 229910001388 sodium aluminate Inorganic materials 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 230000008685 targeting Effects 0.000 description 1
- 235000020234 walnut Nutrition 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
- E21B33/14—Methods or devices for cementing, for plugging holes, crevices or the like for cementing casings into boreholes
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/003—Means for stopping loss of drilling fluid
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
- E21B21/06—Arrangements for treating drilling fluids outside the borehole
Definitions
- the present invention relates to a method of supplying cement slurry, as well as a method of drilling a hole and a method of cementing using the same, and particularly to a method of preventing lost circulation during the drilling of a hole.
- Drilling mud is used for the drilling of a well for oil, natural gas, geothermal energy and hot springs or of a vertical hole, such as a hot water pipe.
- the drilling mud is produced by mixing clay, such as bentonite, with water, and is supplied into a vertical hole in order to transport cuttings to the ground or to protect the wall of the hole. Accordingly, loss of the drilling mud from the vertical hole will cause the cuttings to remain in the hole or cause the wall of the hole to collapse, and increases the drilling cost.
- lost circulation layer The phenomenon in which drilling mud flows out of a vertical hole through a specific part of the wall of the hole and through cavities, cracks, permeable layers and the like in the formation (hereinafter, these are referred to as a lost circulation layer) is generally called lost circulation or mud loss.
- Conventional known measures to prevent the lost circulation include a method of supplying lost circulation materials, such as raw cotton, sawdust and walnut shell, to the drilling mud, and a method of supplying cement slurry into a lost circulation layer and solidifying the cement slurry in the lost circulation layer.
- JPS59-118938 discloses adding hardening accelerator, such as aqueous solution of silicate of soda, to a cement type grout, wherein the hardening accelerator accelerates the hardening of the cement type grout.
- the most reliable method for lost circulation that occurs during the drilling of a vertical hole is to supply cement slurry into the lost circulation layer.
- hardening accelerator may be added to the cement slurry, as disclosed in JPS59-118938.
- the hardening accelerator can accelerate the hardening of the cement slurry, efficiently gelate the cement slurry in the lost circulation layer and close the lost circulation layer.
- the cement slurry is supplied into the hole through a pipe that is called a cementing tool and that is provided in the hole.
- a spacer layer such as water, is interposed between the cement slurry and the hardening accelerator.
- the method of sequentially supplying the cement slurry, the spacer layer and the hardening accelerator complicates the process, leaving room for improvement.
- the cement slurry when supplied into a hole for a purpose other than the drilling of a vertical hole, it is also desired that the cement slurry be prevented from coming into contact with the hardening accelerator in the cementing tool.
- the present invention aims at providing a method of supplying cement slurry, the method being capable of preventing the cement slurry from coming into contact with the hardening accelerator in the cementing tool in a simple manner.
- a method of supplying cement slurry according to the present invention comprising the steps of: adding a capsule to cement slurry, wherein the capsule is filled with hardening accelerator for the cement slurry; and supplying the cement slurry to a hole.
- the capsule is added to the cement slurry, and the cement slurry is supplied through a cementing tool that is provided in the hole.
- the capsule melts or collapses after a specific amount of time passes, wherein the specific amount of time is longer than a flow out time, which is a time for the capsule to flow out of the cementing tool after the capsule is added to the cement slurry.
- the hardening accelerator is isolated from the surrounding cement slurry by the capsule. Therefore, according to the present invention, it is possible to provide a method of supplying cement slurry, the method being capable of preventing the cement slurry from coming into contact with the hardening accelerator in the cementing tool in a simple manner.
- FIG. 1 is a schematic view of an onshore rig to which the present invention can be applied;
- FIGS. 2A and 2B are schematic views illustrating a method of preventing lost circulation according to an embodiment of the present invention
- FIG. 3 is a schematic view of a capsule
- FIGS. 4A and 4B are schematic views illustrating a method of preventing lost circulation according to a comparative example
- FIGS. 5A and 5B are schematic views of inner string cementing
- FIGS. 6A to 6E are schematic views of two-plug cementing
- FIGS. 7A and 7B are schematic views of squeeze cementing.
- FIGS. 8A and 8B are schematic views of plug-back cementing.
- FIG. 1 shows a schematic view of onshore rig 1 according to an embodiment of the present invention.
- a platform called substructure 2 is provided on ground G, and scaffold 3 (also called derrick) is formed on the platform.
- Tubular casing pipe 4 is installed underground below substructure 2
- drill 5 also called a drill string
- Wire 6 is drawn out from draw works 7 that is provided on the top of substructure 2 , and can raise and lower drill 5 via pulley 8 that is provided on the top of scaffold 3 .
- Mud pump 9 that circulates drilling mud is provided on ground G or on the top of substructure 2 .
- Mud tank 12 that stores the drilling mud is provided on ground G. Mud tank 12 is connected to mud pump 9 by line 13 , and mud pump 9 is connected to drill 5 by line 10 .
- Drill 5 includes bit 51 that drills the formation, drill collar 52 that applies force to bit 51 and drill pipe 53 that is connected to drill collar 52 .
- Drill pipe 53 as well as drill collar 52 and bit 51 that are connected to drill pipe 53 , can be rotated around the central axis thereof by means of a rotational drive mechanism (not illustrated) that is provided above drill pipe 5 .
- Drill collar 52 and drill pipe 53 are formed of steel pipes, each having an inner fluid passage that allows the drilling mud to pass through.
- the drilling mud that is supplied from mud pump 9 flows through line 10 , drill pipe 53 and drill collar 52 to be injected toward the bottom of the hole from a nozzle that is provided in bit 51 that is located at the end of drill 5 .
- An apparatus (not illustrated) that removes the cuttings that are contained in the drilling mud is provided on line 11 , so that mud pump 9 can circulate the drilling mud again free of the cuttings.
- facility for supplying cement slurry 14 includes cement slurry tank 15 that stores cement slurry, slurry pump 17 that is connected to cement slurry tank 15 via line 16 and that pumps the cement slurry into the hole, and line 18 that is connected to slurry pump 17 and that merges with line 10 .
- facility for supplying cement slurry 14 includes capsule tank 19 that stores capsules that are filled with hardening accelerator for the cement slurry and capsule supply line 20 that is connected to capsule tank 19 and that merges with line 18 . Accordingly, the capsules are added to the cement slurry downstream of the slurry pump.
- Valve 24 is provided on line 10 between mud pump 9 and the merging point with line 18 , and valve 25 is provided on line 18 . Valve 24 is open and valve 25 is closed during the drilling of the vertical hole.
- Valve 26 is provided on line 18 between slurry pump 17 and the merging point with capsule supply pipe 20 , and valve 27 is provided on capsule supply line 20 . Valves 26 , 27 are closed during the drilling of the vertical hole.
- Casing pipe 4 is used in order to protect wall 21 of the hole.
- outer casing pipe 4 a and inner casing pipe 4 b are provided.
- a vertical hole having a larger diameter than outer casing pipe 4 a is drilled, and outer casing pipe 4 a is then provided in the vertical hole.
- annulus 22 a between outer casing pipe 4 a and wall 21 of the hole is filled with cement 23 a in order to fix outer casing pipe 4 a.
- This operation is a process of filling annulus 22 a with cement slurry (also called cement milk), which is a mixture of cement and water, and of solidifying the cement slurry.
- cement slurry also called cement milk
- drill 5 is lowered into outer casing pipe 4 a to drill a vertical hole having a larger diameter than inner casing pipe 4 b, and inner casing pipe 4 b is provided in the vertical hole.
- annulus 22 b between inner casing pipe 4 b and wall 21 of the hole and between inner casing pipe 4 b and outer casing pipe 4 a is filled with cement 23 b in order to fix inner casing pipe 4 b.
- bit 51 is replaced and the drilling is further proceeded downward below inner casing pipe 4 .
- the drilling mud has the function of taking in cuttings that are generated during the drilling and of transporting the cuttings to the ground, the function of adjusting the pressure in the vertical hole, the function of protecting the wall of the hole in order to prevent the collapse of the formation, the function of cooling bit 51 and so on.
- the drilling mud is a suspension that is made by mixing water with clay, such as bentonite, but the drilling mud is not limited to this, and a wide variety of generally used drilling mud may be used.
- FIG. 2A shows a sectional view of vertical hole 203 and lost circulation layer 202 that communicates with wall 21 of the hole.
- the interior of vertical hole 203 is filled with drilling mud 204 , and vertical hole 203 is in contact with surrounding ground 205 .
- the occurrence of the lost circulation from wall 21 of the hole can be detected based on the flow rate of the drilling mud that is supplied and the flow rate of the drilling mud that is recovered. More specifically, if the flow rate of the drilling mud that is recovered is reduced below the flow rate expected from the flow rate of the drilling mud that is supplied, then it can be presumed that lost circulation has occurred. In addition, the position of bit 51 of drill 5 at the time when the flow rate of the drilling mud that is recovered has been reduced below the flow rate expected from the flow rate of the drilling mud that is supplied is highly likely to correspond to the depth at which the lost circulation has occurred.
- the possible location in vertical hole 203 where the lost circulation has occurred (how deep from the ground lost circulation layer 202 exists) can also be detected.
- injector 54 for injecting cement slurry is attached to the end of drill pipe 53 , drill 5 is lowered again as cementing tool 105 , so as to be installed in the hole.
- the injection port of injector 54 for injecting the cement slurry is provided near the bottom of the hole, which is the bottom that exists when the drilling is halted.
- injector 54 preferably has about the same outer diameter as drill pipe 53 .
- injector 54 may be spaced from the bottom of the hole with a certain distance therebetween. Injector 54 may be omitted.
- valve 24 on line 10 is closed, valves 25 , 26 on line 18 are opened, and slurry pump 17 is activated in order to supply the cement slurry that is stored in tank 15 to line 10 via lines 16 , 18 .
- valve 27 is kept closed during the operation of slurry pump 17 .
- slurry pump 17 is stopped temporarily, valve 27 is opened, and valve 26 is closed.
- the capsules are supplied from capsule supply line 20 to line 18 .
- the capsules may be supplied to line 18 , for example, by their own weight.
- a liquid such as cement slurry
- the capsules may be supplied to line 18 together with the liquid.
- valve 27 is closed, valve 26 is opened, and slurry pump 17 is activated to supply the cement slurry to line 18 .
- the capsules that are filled with the hardening accelerator for the cement slurry can be added, via line 20 , to the cement slurry that flows in line 18 .
- cement slurry 206 to which capsules C are added, is supplied to the hole via cylindrical cementing tool 105 that is provided in the hole.
- the hardening accelerator accelerates the hardening of the cement slurry.
- the hardening accelerator is preferably calcium chloride, silicate of soda (water glass) or mixture thereof.
- Calcium chloride is typically in granular or powdery form, but may be in the form of an aqueous solution.
- Silicate of soda is a thick aqueous solution of sodium silicate and exists in the form of malt syrup.
- the hardening accelerator may also be inorganic compound, such as chloride (NaCl, KCl), nitrous acid (Ca(NO 2 ) 2 , KNO 2 ), nitrate (Ca(NO 3 ) 2 , NaNO 3 , KNOB), sulfate (CaSO 4 , Na 2 SO 4 , K 2 SO 4 ), thiocyanate (NaSCN), alkali (NaOH, KOH), carbonate (Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3 ), alumina-based compound (Al(OH) 3 , Al 2 O 3 ) and alkaline aluminate (NaAlO 2 , Ca(AlO 2 ) 2 ), or inorganic compound, such as amine, gallium salt of organic acid and maleic anhydride.
- the hardening accelerator is not limited to these, and the hardening accelerator may be in liquid or in solid as long as it can fill the capsule.
- capsule C is formed of hardening accelerator 31 , which is the contents of capsule C, and coating material 32 that coats hardening accelerator 31 .
- Capsule C can be produced by a well-known process. The arrangement of capsule C is not limited.
- coating material 32 may be formed of more than one layer. Capsule C, or more precisely, coating material 32 of capsule C gradually melts or collapses after capsule C is added to the cement slurry, and discharges hardening accelerator 31 that fills the interior to the cement slurry after a specific amount of time passes.
- the specific amount of time is set to be a little longer than the time for capsule C to flow out of cementing tool 105 after capsule C is added to the cement slurry (hereinafter, called flow out time).
- capsule C is prevented from melting inside cementing tool 105
- the cement slurry is prevented from hardening inside cementing tool 105 .
- the cement that has hardened is prevented from remaining in cementing tool 105 or from clogging cementing tool 105 .
- the flow out time may be calculated by dividing the total volume of the passage from a location where capsules C are added to the cement slurry (a location where capsule supply line 20 merges with line 18 ) to injector 54 by the flow rate of the cement slurry.
- the specific amount of time and the flow out time depend on the location of the lost circulation layer. When the lost circulation layer is located at a shallow position, the flow out time is short and the specific amount of time may be short. When the lost circulation layer is located at a deep position, the flow out time is long and the specific amount of time must be set long accordingly. In this case, it is preferable to prepare more than one kind of capsules C each having different melting time.
- the flow rate of the cement slurry that is supplied may be controlled depending on the depth of the injection port or the depth of the lost circulation layer such that capsules C melt after they flow out of the injection port of injector 54 .
- the flow rate of slurry pump 17 may be decreased and when the injection port or the lost circulation layer is located at a deep position, the flow rate of slurry pump 17 may be increased.
- the lost circulation is presumed, with a high probability, to have occurred near the position of bit 51 at a time when the flow rate of the drilling mud that is recovered has been reduced below the flow rate expected from the flow rate of the drilling mud that is supplied.
- the lost circulation may also occur at a shallower position, for example, in a lost circulation layer to which measures have been taken in the past against lost circulation.
- the target may be changed to the lost circulation layer to which measures have been taken in the past against the lost circulation.
- the specific amount of time may be adjusted such that capsules C melt or collapse near the target lost circulation layer.
- Capsule C may be formed of synthetic resin, natural polymer materials and so on. Capsule C has melting characteristics that depend on pressure, temperature or pH. In other words, the specific amount of time is a parameter of at least one selected from among pressure, temperature and pH. Since the hole is typically under a high temperature and a high pressure, capsule C preferably melts or collapses when a specific amount of time passes under a predetermined high temperature or a predetermined high pressure. Alternatively, capsule C may melt or collapse when a specific amount of time passes under both a predetermined high temperature and a predetermined high pressure. Since capsule C gradually falls in the hole, the pressure and the temperature vary with time, but the time until the melting occurs can be estimated through prior tests or simulations that take into consideration the variation of the pressure and the temperature. Since the cement slurry is strong alkali, it is also possible to use capsule C that melts or collapses under strong alkali when a specific amount of time passes.
- FIG. 4A shows a method of supplying the hardening accelerator using a spacer layer instead of capsule C.
- spacer layer 62 that consists of water is supplied, and thereafter hardening accelerator 63 is supplied.
- cement slurry 61 that flows first into lost circulation layer 202 continues to proceed forward in lost circulation layer 202 , and hardening accelerator 63 can never catch up with cement slurry 61 .
- cement slurry 61 , spacer layer 62 and hardening accelerator 63 need to be injected repeatedly in order to close lost circulation layer 202 with cement, but this is not desirable from the viewpoint of both time and cost.
- capsules C and the cement slurry are simultaneously supplied in the hole. For this reason, immediately after capsules C melt, the hardening accelerator comes into contact with the cement slurry to cause the cement slurry to harden.
- black capsules C conceptually indicate capsules C that have not yet melted
- white capsules C conceptually indicate capsules C that have melted. Since capsules C do not melt when they move inside cementing tool 105 , and melt after they exit from cementing tool 105 , capsules C can close the circulation lost layer in a short time and with a low cost and prevent the lost circulation from proceeding, while preventing the clogging of cementing tool 105 .
- Capsule C that is filled with the hardening accelerator preferably has about the same specific weight as the cement slurry.
- capsules C in the cement slurry can be transported at about the same velocity as the cement slurry.
- capsules C can be uniformly distributed in the cement slurry, it is possible to cause a large amount of cement slurry to efficiently harden. If the specific weight of capsule C is much larger than the specific weight of the cement slurry, capsules C will flow out of cementing tool 105 earlier than the expected flow out time, and the melting of capsule C may not occur in the desired position.
- the specific weight of capsule C that is filled with the hardening accelerator is preferably 70% or more and 130% or less of the specific weight of the cement slurry, more preferably 90% or more and 110% or less of the specific weight of the cement slurry.
- capsules C are added to the cement slurry downstream of slurry pump 17 that pumps the cement slurry into the hole. This is intended to prevent capsules C from being broken by slurry pump 17 , but if there is no large concern about that, capsule C may be added to the cement slurry upstream of slurry pump 17 , as shown by the broken line in FIG. 1 .
- line 20 a that connects capsule tank 19 to line 16 is provided, and valve 27 a is provided on line 20 a.
- the cement slurry and the capsules may be alternately supplied by switching valve 26 and valve 27 a alternately, as in the above embodiment.
- slurry pump 17 may be operated while keeping both valve 26 and valve 27 a open. Due to the agitating effect of slurry pump 17 , capsules C are further uniformly distributed in the cement slurry.
- the hole may be an inclined hole or a lateral hole.
- Lost circulation may also occur in an inclined hole or a lateral hole during the drilling, and measures may be taken to prevent the lost circulation in the same manner.
- the present invention can also be applied to the cementing.
- Cement generates column hydrostatic pressure when it is in the form of fluid, but when the cement is solidified, loss of the column hydrostatic pressure occurs, which causes the possibility that fluid, such as gas, water and oil, cannot be prevented from gushing from the bottom of the hole.
- the cement that has hardened may generate fine cavities therein, called micro annuluses, that may become passages for fluid, such as gas, water and oil. Fluid, such as gas, water and oil, that flows into the hole may penetrate through the cement layer via the micro annuluses of the cement so as to gush out to the ground.
- cement slurry that is in the process of hardening easily allows fluid, such as gas, water and oil, to pass therethrough, and such phenomenon may cause the fluid to gush out to the ground while the cement slurry is in the process of hardening or may generate cavities in the cement after the cement slurry has hardened.
- fluid such as gas, water and oil
- FIGS. 5A, 5B show the processes of inner string cementing to which the present invention is applied.
- cement slurry 502 to which capsules C are added, is supplied from cementing tool 501 to casing pipe 4 .
- Casing pipe 4 is provided with floating collar 503 .
- Cement slurry 502 is prevented from flowing out to the side of cementing tool 501 by the end of cementing tool 501 abutting against floating collar 503 .
- Cement slurry 502 is pumped into casing pipe 4 , turns around the lower end of casing pipe 4 so as to fill annulus 505 between casing pipe 4 and wall 504 of the hole. Thereafter, as shown in FIG.
- casing pipe 4 is an example of a hollow cylindrical body, and the hollow cylindrical body may also be, for example, a liner.
- the specific weight of capsule C that contains the hardening accelerator is preferably about the same as the specific weight of cement slurry 502 .
- FIGS. 6A to 6E show the processes of two-plug cementing to which the present invention is applied.
- the casing pipe itself is used as a passage to supply the cement slurry.
- first plug 601 is installed, as shown in FIG. 6B .
- preceding water 602 is supplied in order to prevent the cement slurry from mixing with the drilling mud and to wash the inside of casing pipe 4 .
- cement slurry 603 is supplied.
- second plug 604 is installed, and displacement water (mud) 605 is supplied in order to pump cement slurry 603 .
- displacement water (mud) 605 is supplied in order to pump cement slurry 603 .
- first plug 601 engages floating collar 606 that is provided in casing pipe 4 between both ends thereof and is broken by back pressure.
- cement slurry 603 flows downward in casing pipe 4 , turns around the lower end of casing pipe 4 to fill annulus 608 between casing pipe 4 and wall 609 of the hole, as shown in FIGS. 6D and 6E .
- cement slurry 603 hardens.
- the cement that remains in casing pipe 4 is drilled by the bit and is removed in a later process. In the present embodiment, since a cementing tool is not used, the clogging of a cementing tool does not occur.
- cement slurry 603 may not reach every part of annulus 608 .
- capsule C to control the timing of the hardening ensures that annulus 608 is filled with cement slurry 603 .
- FIGS. 7A, 7B show the processes of squeeze cementing to which the present invention is applied.
- the squeeze cementing is a process of remedying imperfect cementing.
- a defect such as a cavity or crack 702 occurs in cement 701 due to reasons, such as imperfect operation and aging, as shown in FIG. 7A .
- a process to remedy the defect may be required.
- hole 705 or a crack is generated on the side of casing pipe 4 and that hole 705 or the crack communicates with a cavity or crack 702 on the backside of casing pipe 4 . In this case, as shown in FIG.
- remedying pipe 703 also called an injection-sub
- cement slurry 704 to which capsules C are added
- cement slurry 704 is pumped into the cavity or crack 702 on the backside of casing pipe 4 through the opening that is provided on the side of remedying pipe 703 and through hole 705 .
- packers 706 are preferably provided above and below the opening of remedying pipe 703 in order to supply cement slurry 704 to a predetermined depth region that includes hole 702 .
- cement slurry 704 can be efficiently supplied to the backside of casing 4 through hole 702 .
- Cement slurry 704 hardens and closes the cavity or crack 702 .
- capsules C When the specific weight of capsule C is about the same as that of cement slurry 704 , capsules C are uniformly distributed in cement slurry 704 . When there is no hole 702 or crack that is open on casing 4 or when hole 702 or the crack is small, hole 702 for pumping the cement slurry may be made in casing 4 . In the present embodiment, since capsules C melt after they flow out of remedying pipe 703 , remedying pipe 703 is prevented from sticking due to the cement that has hardened.
- FIGS. 8A, 8B show the processes of plug-back cementing to which the present invention is applied.
- the plug-back cementing is used for abandonment, regeneration and so on of a vertical hole.
- a plug called cement plug 801 is formed at the bottom of the hole in order to prevent gas or water from gushing out, as shown in FIG. 8A .
- plugs may also be provided in the middle or upper parts of the hole.
- new vertical hole 803 is branched obliquely from old vertical hole 802 at a part between both ends thereof, as shown in FIG. 8B .
- This operation is called side track because new vertical hole 803 is drilled from the side of old vertical hole 802 .
- the drill collar or the drill pipe immediately above the bit may be cut, and a new bit may be attached in order to continue the drilling.
- This is also called side track, as in the case of regenerating a vertical hole.
- plug-back cementing is carried out in order to prevent gas and water from gushing out from the bottom of old vertical hole 802 .
- cement slurry, to which capsules C are added, is supplied, cement plug 801 can be properly formed on the bottom of the hole by capsules C melting near the bottom of the hole.
- capsule CH having a larger specific weight than the cement slurry may be used.
- the specific weight of capsule CH may be adjusted depending on the material of coating material 32 .
- a material having a large specific weight may be added to hardening accelerator 31 .
- capsule CH having a larger specific weight than the cement slurry concentrates at bottom 803 of the hole due to the difference of the specific weight. For this reason, the hardening accelerator can be distributed at bottom 803 of the hole with a high density, and the cement slurry at bottom 803 of the hole can harden more quickly and more properly.
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Abstract
Cement slurry is prevented from coming into contact with hardening accelerator in a cementing tool in a simple manner. The method of supplying cement slurry has the steps of: adding capsule C to cement slurry, wherein capsule C is filled with hardening accelerator for the cement slurry; and supplying the cement slurry to a hole, wherein capsule C is added to the cement slurry, and the cement slurry is supplied through cementing tool 105 that is provided in the hole. Capsule C melts or collapses after a specific amount of time passes, wherein the specific amount of time is longer than a flow out time, which is a time for capsule C to flow out of cementing tool 105 after capsule C is added to the cement slurry.
Description
- The present invention relates to a method of supplying cement slurry, as well as a method of drilling a hole and a method of cementing using the same, and particularly to a method of preventing lost circulation during the drilling of a hole.
- Drilling mud is used for the drilling of a well for oil, natural gas, geothermal energy and hot springs or of a vertical hole, such as a hot water pipe. The drilling mud is produced by mixing clay, such as bentonite, with water, and is supplied into a vertical hole in order to transport cuttings to the ground or to protect the wall of the hole. Accordingly, loss of the drilling mud from the vertical hole will cause the cuttings to remain in the hole or cause the wall of the hole to collapse, and increases the drilling cost. The phenomenon in which drilling mud flows out of a vertical hole through a specific part of the wall of the hole and through cavities, cracks, permeable layers and the like in the formation (hereinafter, these are referred to as a lost circulation layer) is generally called lost circulation or mud loss. Conventional known measures to prevent the lost circulation include a method of supplying lost circulation materials, such as raw cotton, sawdust and walnut shell, to the drilling mud, and a method of supplying cement slurry into a lost circulation layer and solidifying the cement slurry in the lost circulation layer. JPS59-118938 discloses adding hardening accelerator, such as aqueous solution of silicate of soda, to a cement type grout, wherein the hardening accelerator accelerates the hardening of the cement type grout.
- The most reliable method for lost circulation that occurs during the drilling of a vertical hole is to supply cement slurry into the lost circulation layer. In that case, hardening accelerator may be added to the cement slurry, as disclosed in JPS59-118938. The hardening accelerator can accelerate the hardening of the cement slurry, efficiently gelate the cement slurry in the lost circulation layer and close the lost circulation layer. The cement slurry is supplied into the hole through a pipe that is called a cementing tool and that is provided in the hole. Thus, it is necessary to prevent the cement slurry from gelating or hardening in the cementing tool. Conventionally, in order to prevent the cement slurry from coming into contact with the hardening accelerator in the cementing tool. a spacer layer, such as water, is interposed between the cement slurry and the hardening accelerator.
- However, the method of sequentially supplying the cement slurry, the spacer layer and the hardening accelerator complicates the process, leaving room for improvement. In addition, when the cement slurry is supplied into a hole for a purpose other than the drilling of a vertical hole, it is also desired that the cement slurry be prevented from coming into contact with the hardening accelerator in the cementing tool.
- The present invention aims at providing a method of supplying cement slurry, the method being capable of preventing the cement slurry from coming into contact with the hardening accelerator in the cementing tool in a simple manner.
- A method of supplying cement slurry according to the present invention comprising the steps of: adding a capsule to cement slurry, wherein the capsule is filled with hardening accelerator for the cement slurry; and supplying the cement slurry to a hole. The capsule is added to the cement slurry, and the cement slurry is supplied through a cementing tool that is provided in the hole. The capsule melts or collapses after a specific amount of time passes, wherein the specific amount of time is longer than a flow out time, which is a time for the capsule to flow out of the cementing tool after the capsule is added to the cement slurry.
- When the cement slurry is transported in the cementing tool, the hardening accelerator is isolated from the surrounding cement slurry by the capsule. Therefore, according to the present invention, it is possible to provide a method of supplying cement slurry, the method being capable of preventing the cement slurry from coming into contact with the hardening accelerator in the cementing tool in a simple manner.
- The above and other objects, features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate examples of the present invention.
-
FIG. 1 is a schematic view of an onshore rig to which the present invention can be applied; -
FIGS. 2A and 2B are schematic views illustrating a method of preventing lost circulation according to an embodiment of the present invention; -
FIG. 3 is a schematic view of a capsule; -
FIGS. 4A and 4B are schematic views illustrating a method of preventing lost circulation according to a comparative example; -
FIGS. 5A and 5B are schematic views of inner string cementing; -
FIGS. 6A to 6E are schematic views of two-plug cementing; -
FIGS. 7A and 7B are schematic views of squeeze cementing; and -
FIGS. 8A and 8B are schematic views of plug-back cementing. - 1 onshore rig
- 4 casing pipe
- 5 drill
- 9 mud pump
- 14 supply facility for cement slurry
- 17 slurry pump
- 19 capsule tank
- 20 capsule supply pipe
- 21 wall of the hole
- 22 annulus
- 31 hardening accelerator
- 32 coating material
- 51 bit
- 52 drill collar
- 53 drill pipe
- 54 injector
- 105, 501 cementing tool
- 206, 502, 603, 704 cement slurry
- C, CH capsule
- Some embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows a schematic view ofonshore rig 1 according to an embodiment of the present invention. A platform calledsubstructure 2 is provided on ground G, and scaffold 3 (also called derrick) is formed on the platform.Tubular casing pipe 4 is installed underground belowsubstructure 2, and drill 5 (also called a drill string) that drills formation is suspended intocasing pipe 4 by means of wire 6. Wire 6 is drawn out from draw works 7 that is provided on the top ofsubstructure 2, and can raise andlower drill 5 via pulley 8 that is provided on the top ofscaffold 3.Mud pump 9 that circulates drilling mud is provided on ground G or on the top ofsubstructure 2.Mud tank 12 that stores the drilling mud is provided on groundG. Mud tank 12 is connected tomud pump 9 byline 13, andmud pump 9 is connected to drill 5 byline 10. -
Drill 5 includesbit 51 that drills the formation,drill collar 52 that applies force to bit 51 anddrill pipe 53 that is connected to drillcollar 52.Drill pipe 53, as well asdrill collar 52 andbit 51 that are connected to drillpipe 53, can be rotated around the central axis thereof by means of a rotational drive mechanism (not illustrated) that is provided abovedrill pipe 5.Drill collar 52 anddrill pipe 53 are formed of steel pipes, each having an inner fluid passage that allows the drilling mud to pass through. The drilling mud that is supplied frommud pump 9 flows throughline 10,drill pipe 53 anddrill collar 52 to be injected toward the bottom of the hole from a nozzle that is provided inbit 51 that is located at the end ofdrill 5. The drilling mud that takes in cuttings, which are generated during the drilling of theformation using bit 51, is recovered while flowing upward throughannulus 22 betweendrill 5 andwall 21 of the hole and is returned tomud tank 12 throughline 11 on the ground. An apparatus (not illustrated) that removes the cuttings that are contained in the drilling mud is provided online 11, so thatmud pump 9 can circulate the drilling mud again free of the cuttings. - Furthermore,
onshore rig 1 has facility for supplyingcement slurry 14 in order to cope with lost circulation, described later. Facility for supplyingcement slurry 14 includescement slurry tank 15 that stores cement slurry,slurry pump 17 that is connected to cementslurry tank 15 vialine 16 and that pumps the cement slurry into the hole, andline 18 that is connected toslurry pump 17 and that merges withline 10. Furthermore, facility for supplyingcement slurry 14 includescapsule tank 19 that stores capsules that are filled with hardening accelerator for the cement slurry andcapsule supply line 20 that is connected tocapsule tank 19 and that merges withline 18. Accordingly, the capsules are added to the cement slurry downstream of the slurry pump.Valve 24 is provided online 10 betweenmud pump 9 and the merging point withline 18, andvalve 25 is provided online 18.Valve 24 is open andvalve 25 is closed during the drilling of the vertical hole.Valve 26 is provided online 18 betweenslurry pump 17 and the merging point withcapsule supply pipe 20, andvalve 27 is provided oncapsule supply line 20.Valves -
Casing pipe 4 is used in order to protectwall 21 of the hole. In the illustrated example,outer casing pipe 4 a and inner casing pipe 4 b are provided. First, a vertical hole having a larger diameter thanouter casing pipe 4 a is drilled, andouter casing pipe 4 a is then provided in the vertical hole. Next,annulus 22 a betweenouter casing pipe 4 a andwall 21 of the hole is filled withcement 23 a in order to fixouter casing pipe 4 a. This operation is a process of fillingannulus 22 a with cement slurry (also called cement milk), which is a mixture of cement and water, and of solidifying the cement slurry. Then,drill 5 is lowered intoouter casing pipe 4 a to drill a vertical hole having a larger diameter than inner casing pipe 4 b, and inner casing pipe 4 b is provided in the vertical hole. Then, annulus 22 b between inner casing pipe 4 b andwall 21 of the hole and between inner casing pipe 4 b andouter casing pipe 4 a is filled withcement 23 b in order to fix inner casing pipe 4 b. Thereafter, bit 51 is replaced and the drilling is further proceeded downward belowinner casing pipe 4. - The drilling mud has the function of taking in cuttings that are generated during the drilling and of transporting the cuttings to the ground, the function of adjusting the pressure in the vertical hole, the function of protecting the wall of the hole in order to prevent the collapse of the formation, the function of cooling
bit 51 and so on. The drilling mud is a suspension that is made by mixing water with clay, such as bentonite, but the drilling mud is not limited to this, and a wide variety of generally used drilling mud may be used. - Lost circulation may occur during the drilling of a vertical hole. The lost circulation is a phenomenon in which when a lost circulation layer that communicates with
wall 21 of the hole exists in the formation, the drilling mud flows out of the hole into the lost circulation layer. Thus, the lost circulation is also called mud loss.FIG. 2A shows a sectional view ofvertical hole 203 and lostcirculation layer 202 that communicates withwall 21 of the hole. The interior ofvertical hole 203 is filled withdrilling mud 204, andvertical hole 203 is in contact with surroundingground 205. When the mud loss occurs, a part of or the entire part of the drilling mud that is supplied tovertical hole 203 cannot be recovered. Accordingly, the occurrence of the lost circulation fromwall 21 of the hole can be detected based on the flow rate of the drilling mud that is supplied and the flow rate of the drilling mud that is recovered. More specifically, if the flow rate of the drilling mud that is recovered is reduced below the flow rate expected from the flow rate of the drilling mud that is supplied, then it can be presumed that lost circulation has occurred. In addition, the position ofbit 51 ofdrill 5 at the time when the flow rate of the drilling mud that is recovered has been reduced below the flow rate expected from the flow rate of the drilling mud that is supplied is highly likely to correspond to the depth at which the lost circulation has occurred. - Therefore, the possible location in
vertical hole 203 where the lost circulation has occurred (how deep from the ground lostcirculation layer 202 exists) can also be detected. - When the lost circulation is detected,
drill 5 andmud pump 9 are stopped to halt the drilling, then drill 5 is raised out of the hole to the ground using wire 6, andbit 51 anddrill collar 52 are detached. Then, as shown inFIG. 2B ,injector 54 for injecting cement slurry is attached to the end ofdrill pipe 53,drill 5 is lowered again as cementingtool 105, so as to be installed in the hole. The injection port ofinjector 54 for injecting the cement slurry is provided near the bottom of the hole, which is the bottom that exists when the drilling is halted. In order to prevent cementingtool 105 from sticking in the hole,injector 54 preferably has about the same outer diameter asdrill pipe 53. In addition, in order to prevent cementingtool 105 from sticking due to the hardening of the cement slurry,injector 54 may be spaced from the bottom of the hole with a certain distance therebetween.Injector 54 may be omitted. - Next,
valve 24 online 10 is closed,valves line 18 are opened, andslurry pump 17 is activated in order to supply the cement slurry that is stored intank 15 toline 10 vialines capsule supply line 20,valve 27 is kept closed during the operation ofslurry pump 17. After the cement slurry is supplied toline 18,slurry pump 17 is stopped temporarily,valve 27 is opened, andvalve 26 is closed. Thereafter, the capsules are supplied fromcapsule supply line 20 toline 18. The capsules may be supplied toline 18, for example, by their own weight. In order to smoothly supply the capsules toline 18, a liquid, such as cement slurry, may be put incapsule tank 19, and the capsules may be supplied toline 18 together with the liquid. Thereafter,valve 27 is closed,valve 26 is opened, andslurry pump 17 is activated to supply the cement slurry toline 18. By repeating these operations, the capsules that are filled with the hardening accelerator for the cement slurry can be added, vialine 20, to the cement slurry that flows inline 18. As shown inFIG. 2B ,cement slurry 206, to which capsules C are added, is supplied to the hole viacylindrical cementing tool 105 that is provided in the hole. - The hardening accelerator accelerates the hardening of the cement slurry. The hardening accelerator is preferably calcium chloride, silicate of soda (water glass) or mixture thereof. Calcium chloride is typically in granular or powdery form, but may be in the form of an aqueous solution. Silicate of soda is a thick aqueous solution of sodium silicate and exists in the form of malt syrup. The hardening accelerator may also be inorganic compound, such as chloride (NaCl, KCl), nitrous acid (Ca(NO2)2, KNO2), nitrate (Ca(NO3)2, NaNO3, KNOB), sulfate (CaSO4, Na2SO4, K2SO4), thiocyanate (NaSCN), alkali (NaOH, KOH), carbonate (Li2CO3, Na2CO3, K2CO3), alumina-based compound (Al(OH)3, Al2O3) and alkaline aluminate (NaAlO2, Ca(AlO2)2), or inorganic compound, such as amine, gallium salt of organic acid and maleic anhydride. The hardening accelerator is not limited to these, and the hardening accelerator may be in liquid or in solid as long as it can fill the capsule.
- As shown in
FIG. 3 , capsule C is formed of hardeningaccelerator 31, which is the contents of capsule C, andcoating material 32 that coats hardeningaccelerator 31. Capsule C can be produced by a well-known process. The arrangement of capsule C is not limited. For example, coatingmaterial 32 may be formed of more than one layer. Capsule C, or more precisely, coatingmaterial 32 of capsule C gradually melts or collapses after capsule C is added to the cement slurry, anddischarges hardening accelerator 31 that fills the interior to the cement slurry after a specific amount of time passes. The specific amount of time is set to be a little longer than the time for capsule C to flow out of cementingtool 105 after capsule C is added to the cement slurry (hereinafter, called flow out time). Thus, capsule C is prevented from melting inside cementingtool 105, and the cement slurry is prevented from hardening inside cementingtool 105. Accordingly, the cement that has hardened is prevented from remaining in cementingtool 105 or from cloggingcementing tool 105. The flow out time may be calculated by dividing the total volume of the passage from a location where capsules C are added to the cement slurry (a location wherecapsule supply line 20 merges with line 18) toinjector 54 by the flow rate of the cement slurry. The specific amount of time and the flow out time depend on the location of the lost circulation layer. When the lost circulation layer is located at a shallow position, the flow out time is short and the specific amount of time may be short. When the lost circulation layer is located at a deep position, the flow out time is long and the specific amount of time must be set long accordingly. In this case, it is preferable to prepare more than one kind of capsules C each having different melting time. Alternatively, the flow rate of the cement slurry that is supplied (the flow rate of slurry pump 17) may be controlled depending on the depth of the injection port or the depth of the lost circulation layer such that capsules C melt after they flow out of the injection port ofinjector 54. Specifically, when the injection port or the lost circulation layer is located at a shallow position, the flow rate ofslurry pump 17 may be decreased and when the injection port or the lost circulation layer is located at a deep position, the flow rate ofslurry pump 17 may be increased. As described above, the lost circulation is presumed, with a high probability, to have occurred near the position ofbit 51 at a time when the flow rate of the drilling mud that is recovered has been reduced below the flow rate expected from the flow rate of the drilling mud that is supplied. However, the lost circulation may also occur at a shallower position, for example, in a lost circulation layer to which measures have been taken in the past against lost circulation. Accordingly, if the lost circulation does not stop after measures against the lost circulation have been taken targeting the vicinity ofbit 51, the target may be changed to the lost circulation layer to which measures have been taken in the past against the lost circulation. In this case, the specific amount of time may be adjusted such that capsules C melt or collapse near the target lost circulation layer. - Capsule C may be formed of synthetic resin, natural polymer materials and so on. Capsule C has melting characteristics that depend on pressure, temperature or pH. In other words, the specific amount of time is a parameter of at least one selected from among pressure, temperature and pH. Since the hole is typically under a high temperature and a high pressure, capsule C preferably melts or collapses when a specific amount of time passes under a predetermined high temperature or a predetermined high pressure. Alternatively, capsule C may melt or collapse when a specific amount of time passes under both a predetermined high temperature and a predetermined high pressure. Since capsule C gradually falls in the hole, the pressure and the temperature vary with time, but the time until the melting occurs can be estimated through prior tests or simulations that take into consideration the variation of the pressure and the temperature. Since the cement slurry is strong alkali, it is also possible to use capsule C that melts or collapses under strong alkali when a specific amount of time passes.
-
FIG. 4A shows a method of supplying the hardening accelerator using a spacer layer instead of capsule C. In this comparative example, in order to prevent the cement slurry from hardening due to the hardening accelerator in cementingtool 105, aftercement slurry 61 is supplied by cementingtool 105,spacer layer 62 that consists of water is supplied, and thereafter hardeningaccelerator 63 is supplied. However, as shown inFIG. 4B ,cement slurry 61 that flows first into lostcirculation layer 202 continues to proceed forward in lostcirculation layer 202, and hardeningaccelerator 63 can never catch up withcement slurry 61. As a result,cement slurry 61,spacer layer 62 and hardeningaccelerator 63 need to be injected repeatedly in order to close lostcirculation layer 202 with cement, but this is not desirable from the viewpoint of both time and cost. - In the present embodiment, capsules C and the cement slurry are simultaneously supplied in the hole. For this reason, immediately after capsules C melt, the hardening accelerator comes into contact with the cement slurry to cause the cement slurry to harden. In
FIG. 2B , black capsules C conceptually indicate capsules C that have not yet melted, and white capsules C conceptually indicate capsules C that have melted. Since capsules C do not melt when they move inside cementingtool 105, and melt after they exit from cementingtool 105, capsules C can close the circulation lost layer in a short time and with a low cost and prevent the lost circulation from proceeding, while preventing the clogging of cementingtool 105. - Capsule C that is filled with the hardening accelerator preferably has about the same specific weight as the cement slurry. As a result, capsules C in the cement slurry can be transported at about the same velocity as the cement slurry. In addition, since capsules C can be uniformly distributed in the cement slurry, it is possible to cause a large amount of cement slurry to efficiently harden. If the specific weight of capsule C is much larger than the specific weight of the cement slurry, capsules C will flow out of cementing
tool 105 earlier than the expected flow out time, and the melting of capsule C may not occur in the desired position. If the specific weight of capsule C is much smaller than the specific weight of the cement slurry, there is the possibility that capsules C do not flow out of cementingtool 105 due to buoyancy even after the flow out time passes. The specific weight of capsule C that is filled with the hardening accelerator is preferably 70% or more and 130% or less of the specific weight of the cement slurry, more preferably 90% or more and 110% or less of the specific weight of the cement slurry. - As described above, capsules C are added to the cement slurry downstream of
slurry pump 17 that pumps the cement slurry into the hole. This is intended to prevent capsules C from being broken byslurry pump 17, but if there is no large concern about that, capsule C may be added to the cement slurry upstream ofslurry pump 17, as shown by the broken line inFIG. 1 . Specifically, instead ofline 20,line 20 a that connectscapsule tank 19 toline 16 is provided, andvalve 27 a is provided online 20 a. The cement slurry and the capsules may be alternately supplied by switchingvalve 26 andvalve 27 a alternately, as in the above embodiment. However, for example, if the capsules can be supplied intoline 16 by their own weight, thenslurry pump 17 may be operated while keeping bothvalve 26 andvalve 27 a open. Due to the agitating effect ofslurry pump 17, capsules C are further uniformly distributed in the cement slurry. - The hole may be an inclined hole or a lateral hole. Lost circulation may also occur in an inclined hole or a lateral hole during the drilling, and measures may be taken to prevent the lost circulation in the same manner.
- The present invention can also be applied to the cementing. Cement generates column hydrostatic pressure when it is in the form of fluid, but when the cement is solidified, loss of the column hydrostatic pressure occurs, which causes the possibility that fluid, such as gas, water and oil, cannot be prevented from gushing from the bottom of the hole. In addition, the cement that has hardened may generate fine cavities therein, called micro annuluses, that may become passages for fluid, such as gas, water and oil. Fluid, such as gas, water and oil, that flows into the hole may penetrate through the cement layer via the micro annuluses of the cement so as to gush out to the ground. In addition, cement slurry that is in the process of hardening easily allows fluid, such as gas, water and oil, to pass therethrough, and such phenomenon may cause the fluid to gush out to the ground while the cement slurry is in the process of hardening or may generate cavities in the cement after the cement slurry has hardened.
-
FIGS. 5A, 5B show the processes of inner string cementing to which the present invention is applied. As shown inFIG. 5A , in the inner string cementing,cement slurry 502, to which capsules C are added, is supplied from cementingtool 501 tocasing pipe 4.Casing pipe 4 is provided with floatingcollar 503.Cement slurry 502 is prevented from flowing out to the side of cementingtool 501 by the end of cementingtool 501 abutting against floatingcollar 503.Cement slurry 502 is pumped intocasing pipe 4, turns around the lower end ofcasing pipe 4 so as to fillannulus 505 betweencasing pipe 4 andwall 504 of the hole. Thereafter, as shown inFIG. 5B , cementingtool 501 is raised out of the hole. The cement that remains incasing pipe 4 is drilled by the bit and is removed in a later process. In the present embodiment, since capsules C melt after they flow out of cementingtool 501, cementingtool 501 is prevented from sticking due to the cement that has hardened. It should be noted thatcasing pipe 4 is an example of a hollow cylindrical body, and the hollow cylindrical body may also be, for example, a liner. As described above, the specific weight of capsule C that contains the hardening accelerator is preferably about the same as the specific weight ofcement slurry 502. -
FIGS. 6A to 6E show the processes of two-plug cementing to which the present invention is applied. In the two-plug cementing, the casing pipe itself is used as a passage to supply the cement slurry. After casingpipe 4 is provided, as shown inFIG. 6A ,first plug 601 is installed, as shown inFIG. 6B . Next, precedingwater 602 is supplied in order to prevent the cement slurry from mixing with the drilling mud and to wash the inside ofcasing pipe 4. Then,cement slurry 603 is supplied. Thereafter, as shown inFIG. 6C ,second plug 604 is installed, and displacement water (mud) 605 is supplied in order to pumpcement slurry 603. As shown inFIG. 6D ,first plug 601 engages floatingcollar 606 that is provided incasing pipe 4 between both ends thereof and is broken by back pressure. As a result,cement slurry 603 flows downward incasing pipe 4, turns around the lower end ofcasing pipe 4 to fillannulus 608 betweencasing pipe 4 andwall 609 of the hole, as shown inFIGS. 6D and 6E . Thereafter,cement slurry 603 hardens. The cement that remains incasing pipe 4 is drilled by the bit and is removed in a later process. In the present embodiment, since a cementing tool is not used, the clogging of a cementing tool does not occur. However, ifcement slurry 603 hardens incasing pipe 4, then cementslurry 603 may not reach every part ofannulus 608. Using capsule C to control the timing of the hardening ensures thatannulus 608 is filled withcement slurry 603. -
FIGS. 7A, 7B show the processes of squeeze cementing to which the present invention is applied. The squeeze cementing is a process of remedying imperfect cementing. When a defect, such as a cavity or crack 702 occurs incement 701 due to reasons, such as imperfect operation and aging, as shown inFIG. 7A , a process to remedy the defect may be required. Here, suppose thathole 705 or a crack is generated on the side ofcasing pipe 4 and thathole 705 or the crack communicates with a cavity or crack 702 on the backside ofcasing pipe 4. In this case, as shown inFIG. 7B , remedying pipe 703 (also called an injection-sub) is inserted into the hole, andcement slurry 704, to which capsules C are added, is pumped into the cavity or crack 702 on the backside ofcasing pipe 4 through the opening that is provided on the side of remedyingpipe 703 and throughhole 705. In this operation,packers 706 are preferably provided above and below the opening of remedyingpipe 703 in order to supplycement slurry 704 to a predetermined depth region that includeshole 702. Thus,cement slurry 704 can be efficiently supplied to the backside ofcasing 4 throughhole 702.Cement slurry 704 hardens and closes the cavity or crack 702. When the specific weight of capsule C is about the same as that ofcement slurry 704, capsules C are uniformly distributed incement slurry 704. When there is nohole 702 or crack that is open oncasing 4 or whenhole 702 or the crack is small,hole 702 for pumping the cement slurry may be made incasing 4. In the present embodiment, since capsules C melt after they flow out of remedyingpipe 703, remedyingpipe 703 is prevented from sticking due to the cement that has hardened. -
FIGS. 8A, 8B show the processes of plug-back cementing to which the present invention is applied. The plug-back cementing is used for abandonment, regeneration and so on of a vertical hole. When a vertical hole is abandoned, a plug calledcement plug 801 is formed at the bottom of the hole in order to prevent gas or water from gushing out, as shown inFIG. 8A . In case of a deep hole, more than one plug is sequentially formed, and as a result, plugs may also be provided in the middle or upper parts of the hole. When a vertical hole is regenerated, newvertical hole 803 is branched obliquely from oldvertical hole 802 at a part between both ends thereof, as shown inFIG. 8B . This operation is called side track because newvertical hole 803 is drilled from the side of oldvertical hole 802. In addition, although not illustrated, when the bit sticks during the drilling of the vertical hole, the drill collar or the drill pipe immediately above the bit may be cut, and a new bit may be attached in order to continue the drilling. This is also called side track, as in the case of regenerating a vertical hole. In both cases, plug-back cementing is carried out in order to prevent gas and water from gushing out from the bottom of oldvertical hole 802. In the present embodiment, since cement slurry, to which capsules C are added, is supplied,cement plug 801 can be properly formed on the bottom of the hole by capsules C melting near the bottom of the hole. - In the present embodiment, capsule CH having a larger specific weight than the cement slurry may be used. The specific weight of capsule CH may be adjusted depending on the material of
coating material 32. Alternatively, a material having a large specific weight may be added to hardeningaccelerator 31. As shown inFIGS. 8A and 8B , capsule CH having a larger specific weight than the cement slurry concentrates atbottom 803 of the hole due to the difference of the specific weight. For this reason, the hardening accelerator can be distributed atbottom 803 of the hole with a high density, and the cement slurry atbottom 803 of the hole can harden more quickly and more properly. Thus, it is possible to quickly prevent gas and water from gushing out frombottom 803 of the hole and to maintain the integrity of oldvertical hole 802 in the abandonment of a vertical hole or in the side track. In addition, by designing capsules CH such that they melt after they reachbottom 803 of the hole, the cement slurry atbottom 803 of the hole can harden more properly. - Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made without departing from the spirit or scope of the appended claims.
Claims (19)
1. A method of supplying cement slurry comprising the steps of:
adding a capsule to cement slurry, wherein the capsule is filled with hardening accelerator for the cement slurry; and
supplying the cement slurry to a hole, wherein the capsule is added to the cement slurry, and the cement slurry is supplied through a cementing tool that is provided in the hole, wherein the capsule melts or collapses after a specific amount of time passes, wherein the specific amount of time is longer than a flow out time, which is a time for the capsule to flow out of the cementing tool after the capsule is added to the cement slurry.
2. The method of supplying cement slurry according to claim 1 , wherein the capsule is added to the cement slurry downstream of a slurry pump that pumps the cement slurry into the hole.
3. The method of supplying cement slurry according to claim 1 , wherein the capsule is added to the cement slurry upstream of a slurry pump that pumps the cement slurry into the hole.
4. The method of supplying cement slurry according to claim 1 , wherein the hardening accelerator is calcium chloride, silicate of soda or mixture thereof
5. The method of supplying cement slurry according to claim 1 , wherein the capsule has melting characteristics that depend on at least one selected from among pressure, temperature and pH.
6. A method of drilling a hole comprising the steps of:
drilling a hole using a bit that is provided at an end of a drill while supplying drilling mud to the hole through an inner fluid passage of the drill and recovering the drilling mud from an annulus between a wall of the hole and the drill;
stopping the drilling using the drill when occurrence of lost circulation from the wall of the hole is detected based on a flow rate of the drilling mud that is supplied and a flow rate of the drilling mud that is recovered; and
supplying cement slurry to the hole after the drilling is stopped, wherein a capsule is added to the cement slurry by the method of supplying cement slurry according to claim 1 .
7. The method of drilling a hole according to claim 6 , wherein an injection port for the cement slurry of the cementing tool is provided near a bottom of the hole, the bottom existing when the drilling is stopped, and the flow rate of the cement slurry that is supplied is adjusted depending on depth of the injection port such that the capsule melts or collapses after the capsule flows out of the injection port.
8. The method of drilling a hole according to claim 7 , wherein the specific amount of time is adjusted such that the capsule melts or collapses near a location where the lost circulation occurs.
9. The method of drilling a hole according to claim 6 , wherein the drill is raised out of the hole after the drilling is stopped, and the drill is provided in the hole again as the cementing tool after the bit is detached.
10. The method of drilling a hole according to claim 6 , wherein the capsule that is filled with the hardening accelerator has about a same specific weight as the cement slurry.
11. A method of cementing comprising the steps of:
supplying cement slurry to a hole through a cementing tool that is provided in a hollow cylindrical body in the hole, wherein the cement slurry is supplied by the method of supplying cement slurry according to claim 1 , wherein
the cement slurry turns around a lower end of the hollow cylindrical body into an annulus between the hollow cylindrical body and a wall of the hole, flows upward through the annulus to fill the annulus, thereby the hollow cylindrical body is fixed to the wall of the hole.
12. A method of cementing comprising the steps of:
supplying cement slurry to a hole through a cementing tool that is provided in the hole, wherein the cement slurry is supplied by the method of supplying cement slurry according to claim 1 , wherein,
a cement plug is formed at a bottom of the hole by the cement slurry.
13. The method of cementing according to claim 12 , wherein the capsule that is filled with the hardening accelerator has a larger specific weight than the cement slurry.
14. A method of cementing comprising the steps of:
supplying cement slurry to a hole through a cementing tool that is provided in a hollow cylindrical body in the hole, wherein the cement slurry is supplied by the method of supplying cement slurry according to claim 1 , wherein
a defect of cement between the hollow cylindrical body and a wall of the hole communicates with interior of the hollow cylindrical body via a hole that is open on a wall of the hollow cylindrical body, and the cement slurry is supplied to a predetermined depth region that includes the hole of the hollow cylindrical body, and the cement slurry fill the defect via the hole.
15. A capsule that is filled with hardening accelerator for cement slurry, wherein
the capsule is added to the cement slurry, and the cement to which the capsule is added, is supplied to a hole through a cementing tool that is provided in the hole, and
the capsule melts or collapses after a specific amount of time passes, wherein the specific amount a time is longer than a flow out time, which is a time for the capsule to flow out of the cementing tool after the capsule is added to the cement slurry.
16. The capsule according to claim 15 , wherein the hardening accelerator is calcium chloride, silicate of soda or mixture thereof.
17. The capsule according to claim 15 , wherein the capsule has melting characteristics that depend on at least one selected from among pressure, temperature and pH.
18. The capsule according to claim 15 , wherein the capsule that is filled with the hardening accelerator has about a same specific weight as the cement slurry.
19. The capsule according to claim 15 , wherein the capsule that is filled with the hardening accelerator has a larger specific weight than the cement slurry.
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PCT/JP2019/022012 WO2020245882A1 (en) | 2019-06-03 | 2019-06-03 | Cement slurry supplying method, and borehole excavation method and cementing method using said supplying method |
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US17/616,017 Abandoned US20220316287A1 (en) | 2019-06-03 | 2019-06-03 | Method of supplying cement slurry and method of drilling or cementing of well using the same |
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WO (1) | WO2020245882A1 (en) |
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US20230374976A1 (en) * | 2020-10-07 | 2023-11-23 | Board Of Regents, The University Of Texas System | Geothermal well designs and control thereof for extraction of subsurface geothermal power |
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JPS61237792A (en) * | 1985-04-13 | 1986-10-23 | 清水建設株式会社 | Method for casing cementing of production well |
JPH0613789B2 (en) * | 1986-07-07 | 1994-02-23 | 三井建設株式会社 | How to add quick-setting agent |
JPH0791100B2 (en) * | 1986-12-10 | 1995-10-04 | タカタ株式会社 | How to prevent deterioration of concrete and mortar |
JPS63210390A (en) * | 1987-02-27 | 1988-09-01 | 株式会社竹中工務店 | Method of cut-off construction of deap-seated boring hole |
JPH0658071A (en) * | 1991-11-15 | 1994-03-01 | Mitsubishi Materials Corp | Well-head device and cementing method |
JP2939395B2 (en) * | 1992-07-22 | 1999-08-25 | 株式会社テルナイト | Water loss prevention method |
JPH1192188A (en) * | 1997-09-19 | 1999-04-06 | Nippon Kayaku Co Ltd | Aggregate for mortar or concrete and mortar or concrete composition |
JP2001348257A (en) * | 2000-06-06 | 2001-12-18 | Asahi Kasei Corp | Cement admixture capsule |
JP5032871B2 (en) * | 2007-03-29 | 2012-09-26 | ケイミュー株式会社 | Fiber cement board |
JP2013204356A (en) * | 2012-03-29 | 2013-10-07 | Taisei Corp | In-hole flow quantity management system for drilled hole |
JP5705801B2 (en) * | 2012-07-13 | 2015-04-22 | 三菱マテリアルテクノ株式会社 | Well closure device and method for closing it |
AR099799A1 (en) * | 2014-03-21 | 2016-08-17 | Halliburton Energy Services Inc | CEMENT COMPOSITIONS WITH DELAYED FRAGUADO THAT INCLUDE PÓMEZ STONE AND ASSOCIATED METHODS |
WO2016175261A1 (en) * | 2015-04-28 | 2016-11-03 | 株式会社クラレ | Fiber-containing carbonated roof tile and method for manufacturing same |
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US20230374976A1 (en) * | 2020-10-07 | 2023-11-23 | Board Of Regents, The University Of Texas System | Geothermal well designs and control thereof for extraction of subsurface geothermal power |
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