WO2022250544A1 - A mud loss treatment fluid and a method for mud loss treatment - Google Patents

A mud loss treatment fluid and a method for mud loss treatment Download PDF

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Publication number
WO2022250544A1
WO2022250544A1 PCT/NO2022/050118 NO2022050118W WO2022250544A1 WO 2022250544 A1 WO2022250544 A1 WO 2022250544A1 NO 2022050118 W NO2022050118 W NO 2022050118W WO 2022250544 A1 WO2022250544 A1 WO 2022250544A1
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WIPO (PCT)
Prior art keywords
fluid
polymer
tank
drill
granulates
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PCT/NO2022/050118
Other languages
French (fr)
Inventor
Rune FLO
Arild Saasen
Jafar ABDOLLAHI
Inge Manfred Carlsen
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Prores As
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Publication of WO2022250544A1 publication Critical patent/WO2022250544A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
    • C09K8/502—Oil-based compositions
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
    • C09K8/504—Compositions based on water or polar solvents
    • C09K8/506—Compositions based on water or polar solvents containing organic compounds
    • C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
    • C09K8/504—Compositions based on water or polar solvents
    • C09K8/506—Compositions based on water or polar solvents containing organic compounds
    • C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
    • C09K8/512—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
    • C09K8/516—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls characterised by their form or by the form of their components, e.g. encapsulated material
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP 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 DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B27/00—Containers for collecting or depositing substances in boreholes or wells, e.g. bailers, baskets or buckets for collecting mud or sand; Drill bits with means for collecting substances, e.g. valve drill bits
    • E21B27/02—Dump bailers, i.e. containers for depositing substances, e.g. cement or acids

Definitions

  • the invention concerns a mud loss treatment fluid and a method for mud loss treatment.
  • the invention concerns a mix of a water-swelling polymer granulate
  • polymer granulate (1) as a crushed powder of dry, potentially water-swelling polymer with a granulate size spread of below 2 mm in an inert oil in a tank (6), and set these under pressure so that they run out through a tank outlet (61) to subsequently be mixed with a hydrous drill fluid to commence with the swelling.
  • a powder like this will often comprise polymer granulate (1) with a flake shape. Flake-shaped granulates with sharp edges tend to attach themselves to each other and build up a plug which introduces friction to a tank wall in the tank, as well as the channel through which the polymer granulates shall pass.
  • this pore space is approx. 40 % (of volume).
  • the idea we had is based on that when the pressure increased in the polymer container to release the bottom valve, the pore pressure in the support fluid would keep the polymer granulates separated, and release/empty the tank without segregation; this did not occur, as the oil is the first to be forced out.
  • the high viscosity of the oil in the polymer column in the tank causes the oil, due to the permeability in the packed polymer granulates, to be easily drained first, thin support fluid exploits the permeability of the polymer column, and is more or less drained without also scooping up the polymer granulates and leaving an oil-wet amount of granulate in the tank and tank outlet, which would prove difficult to force out through the tank outlet (61), and is prone to create a rubber-like plug when it comes in contact with water, swelling up prior to reaching further out through the drill bit, and to an insufficient degree allowing the penetration into the surrounding geological formation.
  • the invention provides a solution to this problem, and is a mud loss treatment fluid, comprising water-swelling polymer granulate (1) not yet exposed to water,
  • polymer granulates (1) are substantially spherical granulates, and possess a particle size spread of up to 2 mm,
  • polymer granulates (1) constitute a packet, vibrated granulate mix
  • the support fluid (2) comprises an oil (3) which is diluted with a gel mass forming means (4)
  • the mud loss treatment fluid (1, 2, 3, 4) is arranged to be mixed with a suitable hydrous drill fluid (8) externally of the tank outlet in the drill string born tank and be transported to penetrate a mud loss zone (8) surrounding a drilling hole (9), enabling the polymer granulate to continue to swell within the rock types or fractures in the mud loss zone (8), and to stop the fluid loss.
  • the available pore space in the polymer granulate mix may be completely filled with an inert support fluid.
  • the invention also concerns a method for mud loss treatment as stated in independent claim 6. Brief figure explanation
  • Fig. 1 is an illustration of a part of a pipe section behind a drill bit, where a tank containing water-swelling particles (1) stored in low viscosity (i.e. thin) oil is arranged.
  • the figure illustrates the background of the problem in connection with a tank (6) being filled and packed with a granulate size spread amount of water swelling particles (1), and where a pore space between all of the water-swelling particles (1) is filled with a neutral low viscosity (i.e. thin) oil, enabling the water swelling particles (1) to not swell during storage in the oil.
  • the water-swelling particles (1) often come in the form of crushed flakes of an otherwise water-swelling polymer.
  • Fig. 2 illustrates an inlet that is opened into the tank, with the water-swelling material in low viscosity (i.e. thin) oil wholly or partly displacing the oil in the support fluid / particle mix, and as such drain the oil out through the outlet (61).
  • Fig. 3 illustrates a solution to the problems outlined above and as stated in the invention, where the support fluid (2, 3, 4) possesses such a high viscosity (i.e. thick) that it scoops up and carries with it the water-swelling particles (1) out through the outlet without creating any meaningful degree of blockage of the outlet, and where the water- swelling particles are further transported to the leaking formation, for example via the drill bit. It is also possible to allow the outlet contents to go directly to an annulus surrounding a bottom-hole assembly, BHA annulus.
  • Fig. 4 illustrates an embodiment of the invention with a drill string section with an annular storage tank (6) with mud loss treatment fluid (1, 2, 3, 4) according to the invention, stored in the annular tank (6) and with an inlet (60) for a viscous drill fluid from a drill pipe string (5).
  • a piston in the annular tank (6) to separate between the incoming pressure fluid, i.e. the drill fluid, and the viscous mud loss treatment fluid (1, 2, 3, 4) is also arranged in one embodiment of the invention.
  • a ball (65) is shown, which is dropped in order to block a main bore in the drill pipe string (5), enabling the drill fluid to run in through the inlet (60), and the mud loss treatment fluid (1, 2, 3, 4) can penetrate through the outlet (61).
  • Fig. 5 illustrates a development of the invention where the water-swelling particles (1) in one embodiment are substantially spherical and possess a size spread, and are furthermore stored in the tank (6) in a support fluid (2, 3, 4) with a viscosity which enables the support fluid (2, 3, 4) to carry the water- swelling particles (1) with it out through the outlet (61) instead of being drained out of the particle mass.
  • the particles’ spherical form will contribute to reduced friction during pump out.
  • the invention provides a mud loss treatment fluid comprising potentially water swelling polymer granulate (1) (not yet exposed for water),
  • the polymer granulates (1) possess a particle size spread, preferably up to 2 mm
  • polymer granulates (1) constitute a packed, vibrated granulate mix
  • the support fluid (2) in the form of the oil gel mass (3, 4) and the water swelling polymer granulates (1) is arranged to be stored in a drill string (5) born tank (6) behind a drill bit (7),
  • the mud loss treatment fluid (1, 2, 3, 4) is arranged to be mixed with a suitable hydrous drill fluid (8) externally of the tank outlet, and transported to penetrate a mud loss zone (8) surrounding a drilling hole (9) enabling the polymer granulates to be arranged to continue to swell within the rock types or fractures in the mud loss zone (8), and to stop the fluid loss.
  • the oil gel mass (2, 3, 4) arranged to, during storage and during the passage through the tank outlet (61), constitute a membrane surrounding the polymer granulates (1), and to be exposed to shearing forces following a passage out through the tank outlet (61) and the resulting release from the polymer granulates (1) enabling the polymer granulates to be exposed to hydrous drilling fluid (8) in order to start swelling.
  • the viscosity of the oil gel mass (2, 3, 4) is adjusted to be forced out of the tank as a complete oil gel mass (2, 3, 4) together with the polymer granulates (1) without segregation under drilling-sensitive temperatures.
  • the oil gel mass with particles may consequently possess an even higher viscosity during production and “packing” in the tank (6) in the laboratory or on deck, and appear as a relatively solid mass that can more or less be mechanically processed, or must be heated in order to be introduced into the tank.
  • the polymer granulates (1) are a crushed powder of dry, potentially water-swelling polymer with a granulate size spread of below 2 mm.
  • a powder like this will often comprise polymer granulate (1) with a flake shape.
  • Flake-shaped granulates with sharp edges tend to attach themselves to each other and build up a plug which introduces friction to a tank wall in the tank, as well as the channel through which the polymer granulates shall pass, however, we posit that the high viscosity support fluid (2) will alleviate this disadvantage to a significant degree, and bring the polymer granulates (1) out through the outlet.
  • the polymer granulates (1) are as mentioned a crushed powder of dry, potentially water- swelling polymer with the granulate size spread of below 2 mm.
  • the support fluid (2) in the form of the oil gel mass (3, 4) and the polymer granulates (1), is stored in a drill string (5) born tank (6) behind a drill bit (7), where the tank (6) is cylindrical and possesses a rear piston (62) arranged to receive back pressure from the drill pipe string (5) and to apply pressure against the support fluid (2, 3, 4) and the polymer granulates (1) in the direction of the tank outlet (61).
  • the tank can be cylindrical and arranged in a drill pipe section, preferably behind the drill collars in a drill string.
  • the tank can be annularly cylindrical as indicated in Fig. 3, 4 and 5, where axial longitudinal sections are shown.
  • the polymer granulates (1) are substantially spherical granulates of dry, potentially water-swelling polymers with a granulate size spread of below 2 mm. See Fig. 5. We assume that the spherical granulates will reduce the risk of blockage in the tank outlet (61), and will also allow for a tighter packing of the polymer granulates (1).
  • the invention also provides a method for mud loss treatment, comprising the following steps:
  • mud loss treatment fluid (1, 2, 3, 4) is mixed with a suitable hydrous drill fluid (8) externally of the tank outlet, and transported to, as well as penetrating a mud loss zone (8) surrounding the bore hole (9).
  • the oil gel mass (2, 3, 4) constitutes, during storage and during the passage through the tank outlet (61), a membrane surrounding the polymer granulates (1), and is arranged to be exposed to the shearing forces that may occur following the passage out through the tank outlet (61), and preferably out through the drill bit (7), where the pressure drop is significant, resulting in a release of the polymer granulates (1) enabling the polymer granulates to be exposed to the hydrous drilling fluid (8) in order to start swelling.
  • the tank outlet (61) leads from the tank (6) to a drill fluid (8) channel behind the drill bit (for example a central drilling in a drill collar (10)), and further out through drill bit nozzles (71) in the drill bit (7), and where the pressure drop and the resulting shearing forces in the drill bit nozzles (71) constitute a significant part of the shearing forces exposing the polymer granulates (1) to hydrous drill fluid.
  • a drill fluid (8) for example a central drilling in a drill collar (10)
  • drill bit nozzles (71) in the drill bit (7) and where the pressure drop and the resulting shearing forces in the drill bit nozzles (71) constitute a significant part of the shearing forces exposing the polymer granulates (1) to hydrous drill fluid.
  • One alternative is to allow the tank outlet to lead directly to the annulus in the event that it is desired to remediate drill fluid loss higher up, i.e. more proximal than the drill bit.
  • the tank (6) can as such be placed down by the drill collar
  • the design of the tank (6) is not limited to anything else than it being placed in the drill string behind (in any position there) the drill bit (7), and also not being bound to releasing the fluid out through the drill bit (7), but perhaps rather directly from the tank (6) to a drill string annulus.
  • the rear piston (62) is utilized, in a cylindrical tank (6), which is arranged to receive back pressure from the drill pipe string (5) in order to press up against the support fluid (2, 3, 4) and the polymer granulates (1) in a direction towards the tank outlet (61), please see Fig. 4.
  • an additive with the base oil we utilize (one example is EDC 95-11) in order to cross-link the oil molecules to a gel like consistence with a viscosity, enabling the granulates to, to a certain degree, retain their reciprocal placement in the gel-like gel oil, also when subjected to pressure from one end of the tank (6).
  • the purpose is to form an improved and more suitable support fluid (2, 3, 4) that can be mixed with polymer particles (1) to achieve an acceptable spread, and at the same time maintain the necessary pore pressure in the polymer mix during release from the container and further out through BHA and the drill bit.
  • the particles (1) possess a spherical form.
  • Water-swelling particles (1) with a spherical form can be formed through continuous rolling of growing particles (1) in an evaporated solution of polymer, instead of crushing dried, water- swelling polymers producing flake-shaped particles.
  • the design of the tank (6) is not limited to anything else than it being placed in the drill string behind (in any position there) the drill bit (7), and also not being bound to releasing the fluid out through the drill bit (7), but alternatively directly from the tank (6) to the annulus of the drill string.

Abstract

The invention is a mud loss treatment fluid comprising water-swelling polymer granulates (1), where the polymer granulates (1) possess a particle size spread up to 2 mm, where the polymer granulates (1) constitute a packed, vibrated granular mix, where available pore space in the polymer granulate mix is preferably completely filled with an inert support fluid (2) with regards to swelling, where the support fluid (2) comprises an oil (3) diluted with a gel mass-forming means (4), where the support fluid (2) in the form of the oil gel mass (3, 4) and the polymer granulates (1) is arranged to be stored in a drill string (5) born tank (6) behind a drill bit (7), the support fluid (2, 3, 4) under pressure being arranged to be pushed out through a tank outlet (61) as an unseparated mass of polymer granulates (1) in gel mass (2, 3, 4), where mud loss treatment fluid (1, 2, 3, 4) is arranged to be mixed with a passing, hydrous drill fluid (8) outside of the tank outlet and to be transported to and penetrated into a mud loss zone (8) surrounding the drilling hole (9).

Description

A mud loss treatment fluid and a method for mud loss treatment
The invention concerns a mud loss treatment fluid and a method for mud loss treatment.
More specifically, the invention concerns a mix of a water-swelling polymer granulate
(1) stored in an inert carrying case (2) with regard to swelling, where the support fluid
(2) comprises an oil (3) diluted with a gel mass forming means (4), and arranged to be stored in a drill string (5) born tank (6) behind a drill bit (7), enabling the carrying case (2, 3, 4) under pressure to be arranged in order to be forced out through a tank outlet (61) as an unseparated mass of polymer granulate (1) in the gel mass (2, 3,
4), and arranged to subsequently be mixed with a suitable hydrous drill fluid (8) externally of the tank outlet, and transported to penetrate a mud loss zone (8) surrounding a drilling hole (9).
Background technique:
It is known to release water-swelling polymer particles from a drill pipe string born tank to the drill sludge in order to run out to a mud loss zone during drilling, and penetrate rock types or fractures in the geological formation in order to swell and thus seal the formation, thereby stopping or reducing the mud loss.
The applicant has carried out experiments regarding providing polymer granulate (1) as a crushed powder of dry, potentially water-swelling polymer with a granulate size spread of below 2 mm in an inert oil in a tank (6), and set these under pressure so that they run out through a tank outlet (61) to subsequently be mixed with a hydrous drill fluid to commence with the swelling. A powder like this will often comprise polymer granulate (1) with a flake shape. Flake-shaped granulates with sharp edges tend to attach themselves to each other and build up a plug which introduces friction to a tank wall in the tank, as well as the channel through which the polymer granulates shall pass. Through lab testing, we have utilized a thin base oil to fill up the gaps in the polymer column (the pore space). For dry, packed, and vibrated polymer, this pore space is approx. 40 % (of volume). The idea we had is based on that when the pressure increased in the polymer container to release the bottom valve, the pore pressure in the support fluid would keep the polymer granulates separated, and release/empty the tank without segregation; this did not occur, as the oil is the first to be forced out. The high viscosity of the oil in the polymer column in the tank causes the oil, due to the permeability in the packed polymer granulates, to be easily drained first, thin support fluid exploits the permeability of the polymer column, and is more or less drained without also scooping up the polymer granulates and leaving an oil-wet amount of granulate in the tank and tank outlet, which would prove difficult to force out through the tank outlet (61), and is prone to create a rubber-like plug when it comes in contact with water, swelling up prior to reaching further out through the drill bit, and to an insufficient degree allowing the penetration into the surrounding geological formation.
Brief summary of the invention
The invention provides a solution to this problem, and is a mud loss treatment fluid, comprising water-swelling polymer granulate (1) not yet exposed to water,
- where the polymer granulates (1) are substantially spherical granulates, and possess a particle size spread of up to 2 mm,
- where the polymer granulates (1) constitute a packet, vibrated granulate mix,
- where available pore space in the polymer granulate mix is filled with an inert support fluid (2) with regard to swelling,
- where the support fluid (2) comprises an oil (3) which is diluted with a gel mass forming means (4),
- where the support fluid (2) in the form of the oil gel mass (3, 4) and the polymer granulates (1) are stored in a drill string (5) born tank (6) behind a drill bit (7),
- enabling the support fluid (2, 3, 4) under pressure to be arranged to be forced out through a tank outlet (61) as an unseparated mass of polymer granulate (1) in the oil gel mass (2, 3, 4),
- where the mud loss treatment fluid (1, 2, 3, 4) is arranged to be mixed with a suitable hydrous drill fluid (8) externally of the tank outlet in the drill string born tank and be transported to penetrate a mud loss zone (8) surrounding a drilling hole (9), enabling the polymer granulate to continue to swell within the rock types or fractures in the mud loss zone (8), and to stop the fluid loss.
In one embodiment, the available pore space in the polymer granulate mix may be completely filled with an inert support fluid.
The invention also concerns a method for mud loss treatment as stated in independent claim 6. Brief figure explanation
Fig. 1 is an illustration of a part of a pipe section behind a drill bit, where a tank containing water-swelling particles (1) stored in low viscosity (i.e. thin) oil is arranged. The figure illustrates the background of the problem in connection with a tank (6) being filled and packed with a granulate size spread amount of water swelling particles (1), and where a pore space between all of the water-swelling particles (1) is filled with a neutral low viscosity (i.e. thin) oil, enabling the water swelling particles (1) to not swell during storage in the oil. The water-swelling particles (1) often come in the form of crushed flakes of an otherwise water-swelling polymer.
Fig. 2 illustrates an inlet that is opened into the tank, with the water-swelling material in low viscosity (i.e. thin) oil wholly or partly displacing the oil in the support fluid / particle mix, and as such drain the oil out through the outlet (61). This presents a risk of blockage of the outlet (61) with the water- swelling particles, and unwanted penetration of hydrous drill fluid to the water-swelling particles, which precipitates a premature swelling, which in turn may result in a viscous mass that flows and penetrates poorly out through the outlet (61), which may be a premature swelling in relation to the pore openings to be penetrated into in the mud loss zone.
Fig. 3 illustrates a solution to the problems outlined above and as stated in the invention, where the support fluid (2, 3, 4) possesses such a high viscosity (i.e. thick) that it scoops up and carries with it the water-swelling particles (1) out through the outlet without creating any meaningful degree of blockage of the outlet, and where the water- swelling particles are further transported to the leaking formation, for example via the drill bit. It is also possible to allow the outlet contents to go directly to an annulus surrounding a bottom-hole assembly, BHA annulus.
Fig. 4 illustrates an embodiment of the invention with a drill string section with an annular storage tank (6) with mud loss treatment fluid (1, 2, 3, 4) according to the invention, stored in the annular tank (6) and with an inlet (60) for a viscous drill fluid from a drill pipe string (5). A piston in the annular tank (6) to separate between the incoming pressure fluid, i.e. the drill fluid, and the viscous mud loss treatment fluid (1, 2, 3, 4) is also arranged in one embodiment of the invention. In this embodiment, a ball (65) is shown, which is dropped in order to block a main bore in the drill pipe string (5), enabling the drill fluid to run in through the inlet (60), and the mud loss treatment fluid (1, 2, 3, 4) can penetrate through the outlet (61). Fig. 5 illustrates a development of the invention where the water-swelling particles (1) in one embodiment are substantially spherical and possess a size spread, and are furthermore stored in the tank (6) in a support fluid (2, 3, 4) with a viscosity which enables the support fluid (2, 3, 4) to carry the water- swelling particles (1) with it out through the outlet (61) instead of being drained out of the particle mass. The particles’ spherical form will contribute to reduced friction during pump out.
Description of embodiments of the invention
The invention provides a mud loss treatment fluid comprising potentially water swelling polymer granulate (1) (not yet exposed for water),
- where the polymer granulates (1) possess a particle size spread, preferably up to 2 mm
- where the polymer granulates (1) constitute a packed, vibrated granulate mix
- where available pore space in the polymer granulate mix is preferably completely filled with an inert support fluid (2) with regard to swelling, where the support fluid (2) comprises an oil (3) diluted with a gel mass forming means (4),
- where the support fluid (2) in the form of the oil gel mass (3, 4) and the water swelling polymer granulates (1) is arranged to be stored in a drill string (5) born tank (6) behind a drill bit (7),
- enabling the carrying case (2, 3, 4) under pressure to be arranged in order to be forced out through a tank outlet (61) as an unseparated mass of polymer granulate (1) in the gel mass (2, 3, 4),
- where the mud loss treatment fluid (1, 2, 3, 4) is arranged to be mixed with a suitable hydrous drill fluid (8) externally of the tank outlet, and transported to penetrate a mud loss zone (8) surrounding a drilling hole (9) enabling the polymer granulates to be arranged to continue to swell within the rock types or fractures in the mud loss zone (8), and to stop the fluid loss.
In one embodiment of the invention, the oil gel mass (2, 3, 4) arranged to, during storage and during the passage through the tank outlet (61), constitute a membrane surrounding the polymer granulates (1), and to be exposed to shearing forces following a passage out through the tank outlet (61) and the resulting release from the polymer granulates (1) enabling the polymer granulates to be exposed to hydrous drilling fluid (8) in order to start swelling. In one embodiment of the invention, the viscosity of the oil gel mass (2, 3, 4) is adjusted to be forced out of the tank as a complete oil gel mass (2, 3, 4) together with the polymer granulates (1) without segregation under drilling-sensitive temperatures. The oil gel mass with particles may consequently possess an even higher viscosity during production and “packing” in the tank (6) in the laboratory or on deck, and appear as a relatively solid mass that can more or less be mechanically processed, or must be heated in order to be introduced into the tank.
In one embodiment of the invention, the polymer granulates (1) are a crushed powder of dry, potentially water-swelling polymer with a granulate size spread of below 2 mm. A powder like this will often comprise polymer granulate (1) with a flake shape. Flake-shaped granulates with sharp edges tend to attach themselves to each other and build up a plug which introduces friction to a tank wall in the tank, as well as the channel through which the polymer granulates shall pass, however, we posit that the high viscosity support fluid (2) will alleviate this disadvantage to a significant degree, and bring the polymer granulates (1) out through the outlet.
In one embodiment of the invention, the polymer granulates (1) are as mentioned a crushed powder of dry, potentially water- swelling polymer with the granulate size spread of below 2 mm.
In one embodiment of the invention, the support fluid (2), in the form of the oil gel mass (3, 4) and the polymer granulates (1), is stored in a drill string (5) born tank (6) behind a drill bit (7), where the tank (6) is cylindrical and possesses a rear piston (62) arranged to receive back pressure from the drill pipe string (5) and to apply pressure against the support fluid (2, 3, 4) and the polymer granulates (1) in the direction of the tank outlet (61). The tank can be cylindrical and arranged in a drill pipe section, preferably behind the drill collars in a drill string. The tank can be annularly cylindrical as indicated in Fig. 3, 4 and 5, where axial longitudinal sections are shown.
In another embodiment of the invention, the polymer granulates (1) are substantially spherical granulates of dry, potentially water-swelling polymers with a granulate size spread of below 2 mm. See Fig. 5. We assume that the spherical granulates will reduce the risk of blockage in the tank outlet (61), and will also allow for a tighter packing of the polymer granulates (1). The invention also provides a method for mud loss treatment, comprising the following steps:
- provision of mud loss treatment fluid according to the invention and the description above,
- arrangement of the support fluid (2) in the form of oil gel mass (3, 4) and the polymer granulates (1) in a drill string born tank (6) behind a drill bit (7),
- lower the tank (6) with the drill bit (7) on the drill string (5) and drill in a bore hole,
- continuously monitor any occurrence of an unwanted degree of drill fluid loss; and
- upon detection of an unwanted degree of drill fluid loss,
- force the oil gel mass support fluid (2, 3, 4) under pressure out through a tank outlet (61) as a mainly unseparated mass of polymer granulates (1) in the oil gel mass support fluid (2, 3, 4),
- where mud loss treatment fluid (1, 2, 3, 4) is mixed with a suitable hydrous drill fluid (8) externally of the tank outlet, and transported to, as well as penetrating a mud loss zone (8) surrounding the bore hole (9).
In one embodiment of the method of the invention, the oil gel mass (2, 3, 4) constitutes, during storage and during the passage through the tank outlet (61), a membrane surrounding the polymer granulates (1), and is arranged to be exposed to the shearing forces that may occur following the passage out through the tank outlet (61), and preferably out through the drill bit (7), where the pressure drop is significant, resulting in a release of the polymer granulates (1) enabling the polymer granulates to be exposed to the hydrous drilling fluid (8) in order to start swelling.
In one embodiment of the method, the tank outlet (61) leads from the tank (6) to a drill fluid (8) channel behind the drill bit (for example a central drilling in a drill collar (10)), and further out through drill bit nozzles (71) in the drill bit (7), and where the pressure drop and the resulting shearing forces in the drill bit nozzles (71) constitute a significant part of the shearing forces exposing the polymer granulates (1) to hydrous drill fluid. One alternative is to allow the tank outlet to lead directly to the annulus in the event that it is desired to remediate drill fluid loss higher up, i.e. more proximal than the drill bit. The tank (6) can as such be placed down by the drill collars behind the drill bit (7), or it can be a tank placed further back on the drill pipe string.
The design of the tank (6) is not limited to anything else than it being placed in the drill string behind (in any position there) the drill bit (7), and also not being bound to releasing the fluid out through the drill bit (7), but perhaps rather directly from the tank (6) to a drill string annulus.
In one embodiment of the invention, the rear piston (62) is utilized, in a cylindrical tank (6), which is arranged to receive back pressure from the drill pipe string (5) in order to press up against the support fluid (2, 3, 4) and the polymer granulates (1) in a direction towards the tank outlet (61), please see Fig. 4.
As such, the inventors have suggested to utilize an additive with the base oil we utilize (one example is EDC 95-11) in order to cross-link the oil molecules to a gel like consistence with a viscosity, enabling the granulates to, to a certain degree, retain their reciprocal placement in the gel-like gel oil, also when subjected to pressure from one end of the tank (6). The purpose is to form an improved and more suitable support fluid (2, 3, 4) that can be mixed with polymer particles (1) to achieve an acceptable spread, and at the same time maintain the necessary pore pressure in the polymer mix during release from the container and further out through BHA and the drill bit.
In one embodiment of the invention, the particles (1) possess a spherical form. Water-swelling particles (1) with a spherical form can be formed through continuous rolling of growing particles (1) in an evaporated solution of polymer, instead of crushing dried, water- swelling polymers producing flake-shaped particles.
Our laboratory trials with variable parameters (pressure, restrictions, push mechanisms) show that thin support fluid exploit the permeability of the polymer column, and more or less drain WITHOUT picking up polymers when in transit, see Fig. 1 and 2. The inventors have suggested to utilize an additive to the base oil that we utilize (EDC 95-11) in order to cross-link the oil molecules to a gel-like consistence with an optimal viscosity. This will in turn produce a much more suitable support fluid that can be mixed with polymer particles to achieve an acceptable spread, and at the same time maintain the necessary pore pressure in the polymer mix during release from the container and further out through the bottom-hole assembly and the drill bit, see Fig. 3 and 5.
The design of the tank (6) is not limited to anything else than it being placed in the drill string behind (in any position there) the drill bit (7), and also not being bound to releasing the fluid out through the drill bit (7), but alternatively directly from the tank (6) to the annulus of the drill string.

Claims

PATENT CLAIMS
1. A mud loss treatment fluid comprising water-swelling polymer granulate (1).
- where the polymer granulates (1) are substantially spherical granulates and possess a particle size spread of up to 2 mm
- where the polymer granulates (1) constitute a packed, vibrated granulate
- where available pore space in the polymer granulate mix is preferably completely filled with an inert support fluid (2) with regard to swelling
- where the support fluid (2) comprises an oil (3) which is diluted with a gel mass forming means (4)
- where the support fluid (2) in the form of the oil gel mass (3, 4) and the polymer granulates (1) are arranged to be stored in a drill string born tank (6) behind a drill bit (7),
- enabling the support fluid (2, 3, 4) under pressure to be arranged to be forced out through a tank outlet (61) as an unseparated mass of polymer granulate (1) in the oil gel mass (2, 3, 4),
- where mud loss treatment fluid (1, 2, 3, 4) is arranged to be mixed with a suitable hydrous drill fluid (8) externally of the tank outlet (61) and be transported to penetrate a mud loss zone (8) surrounding a drilling hole (9).
2. The mud loss treatment fluid according to claim 1,
- where the oil gel mass (2, 3, 4) arranged to, during storage and during the passage through the tank outlet (61), constitute a membrane surrounding the polymer granulates (1), and to be exposed to shearing forces following a passage out through the tank outlet (61) and the resulting release from the polymer granulates (1), enabling the polymer granulates to be exposed to hydrous drilling fluid (8) in order to start swelling.
3. The mud loss treatment fluid according to claim 1 or 2,
- where the viscosity of the oil gel mass (2, 3, 4) is adjusted to be forced out of the tank as a complete oil gel mass (2, 3, 4) together with the polymer granulates (1) without segregation during drilling-sensitive temperatures.
4. The mud loss treatment fluid according to claim 1 - 3, - where the polymer granulates (1) are a crushed powder of dry, potentially water swelling polymer with a granulate size spread of below 2 mm.
5. The mud loss treatment fluid according to any of claim 1 - 4,
- where the support fluid (2) in the form of the oil gel mass (3, 4) and the polymer granulates (1) are stored in a drill string (5) born tank (6) behind a drill bit (7), and
- where the tank (6) is cylindrical and possesses a rear piston (62) arranged to receive back pressure from the drill pipe string (5) and to apply pressure against the support fluid (2, 3, 4) and the polymer granulates (1) in the direction of the tank outlet (61).
6. A method for mud loss treatment, comprising provision of mud loss treatment fluid according to claim 1 - 5,
- arrangement of the support fluid (2) in the form of the oil gel mass (3, 4) and the polymer granulates (1) in a drill string born tank (6) behind a drill bit (7),
- lowering the tank (6) with the drill bit (7) on the drill string (5) and drill in a bore hole,
- continuously monitoring any occurrence of an unwanted degree of drill fluid loss,
- upon detection of an unwanted degree of drill fluid loss,
- forcing the oil gel mass support fluid (2, 3, 4) under pressure out through a tank outlet (61) as an unseparated mass of polymer granulates (1) in the oil gel mass support fluid (2, 3, 4),
- where mud loss treatment fluid (1, 2, 3, 4) is mixed with a suitable hydrous drill fluid (8) externally of the tank outlet, and transported to, as well as penetrating, a mud loss zone (8) surrounding the bore hole (9).
7. The method for mud loss treatment according to claim 6,
- where the oil gel mass (2, 3, 4) constitutes, during storage and during the passage through the tank outlet (61), a membrane surrounding the polymer granulates (1), and is exposed to shearing forces following the passage out through the tank outlet (61), resulting in a release of the polymer granulates (1) enabling the polymer granulates to be exposed to the hydrous drilling fluid (8) in order to start swelling.
8. The method for mud loss treatment according to claim 6 or 7,
- where the tank outlet (61) leads from the tank (6) to a drill fluid (8) channel behind the drill bit (7), and where the pressure drop and the resulting shearing forces in the drill bit nozzles (71) constitute a significant part of the shearing forces exposing the polymer granulates (1) to hydrous drill fluid.
9. The method for mud loss treatment according to any of claim 6 to 8,
- application in a cylindrical tank (6) with a rear piston (62), and to receive back pressure from the drill pipe string (5) in order to press up against the support fluid (2, 3, 4) and the polymer granulates (1) in a direction towards the tank outlet (61).
PCT/NO2022/050118 2021-05-27 2022-05-25 A mud loss treatment fluid and a method for mud loss treatment WO2022250544A1 (en)

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US20090151963A1 (en) * 2007-12-13 2009-06-18 Sortwell Edwin T Method of Preventing or Extinguishing Fires
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