EP4051751A1 - High pressure drilling fluid additive - Google Patents
High pressure drilling fluid additiveInfo
- Publication number
- EP4051751A1 EP4051751A1 EP20881363.4A EP20881363A EP4051751A1 EP 4051751 A1 EP4051751 A1 EP 4051751A1 EP 20881363 A EP20881363 A EP 20881363A EP 4051751 A1 EP4051751 A1 EP 4051751A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- drilling fluid
- fibres
- particle size
- microns
- blend
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000012530 fluid Substances 0.000 title claims abstract description 194
- 238000005553 drilling Methods 0.000 title claims abstract description 192
- 239000000654 additive Substances 0.000 title claims abstract description 102
- 230000000996 additive effect Effects 0.000 title claims abstract description 96
- 239000002245 particle Substances 0.000 claims abstract description 160
- 239000000203 mixture Substances 0.000 claims abstract description 92
- 238000009826 distribution Methods 0.000 claims abstract description 65
- 230000015572 biosynthetic process Effects 0.000 claims description 52
- 238000000034 method Methods 0.000 claims description 18
- 239000000835 fiber Substances 0.000 claims description 11
- 239000006187 pill Substances 0.000 claims description 9
- 238000007789 sealing Methods 0.000 claims description 8
- 239000011121 hardwood Substances 0.000 claims description 7
- 240000002871 Tectona grandis Species 0.000 claims description 5
- 229920002522 Wood fibre Polymers 0.000 claims description 3
- 238000005755 formation reaction Methods 0.000 description 49
- 238000012360 testing method Methods 0.000 description 20
- 239000004576 sand Substances 0.000 description 19
- 230000009545 invasion Effects 0.000 description 11
- 239000011159 matrix material Substances 0.000 description 11
- 239000012065 filter cake Substances 0.000 description 10
- 230000035699 permeability Effects 0.000 description 9
- 239000011148 porous material Substances 0.000 description 9
- 239000007787 solid Substances 0.000 description 8
- 239000000440 bentonite Substances 0.000 description 7
- 229910000278 bentonite Inorganic materials 0.000 description 7
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 7
- 238000005549 size reduction Methods 0.000 description 7
- 238000005520 cutting process Methods 0.000 description 6
- 230000002706 hydrostatic effect Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000003921 particle size analysis Methods 0.000 description 4
- 239000000523 sample Substances 0.000 description 4
- 238000007873 sieving Methods 0.000 description 4
- 239000011800 void material Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229920003043 Cellulose fiber Polymers 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 230000000717 retained effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000004888 barrier function Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000013043 chemical agent Substances 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000001627 detrimental effect Effects 0.000 description 2
- 230000007717 exclusion Effects 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000565 sealant Substances 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- 235000017060 Arachis glabrata Nutrition 0.000 description 1
- 244000105624 Arachis hypogaea Species 0.000 description 1
- 235000010777 Arachis hypogaea Nutrition 0.000 description 1
- 235000018262 Arachis monticola Nutrition 0.000 description 1
- 241000207923 Lamiaceae Species 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000013533 biodegradable additive Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 239000010903 husk Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000006028 limestone Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 235000020232 peanut Nutrition 0.000 description 1
- 235000020030 perry Nutrition 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000013074 reference sample Substances 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000005029 sieve analysis Methods 0.000 description 1
- 241000894007 species Species 0.000 description 1
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- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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
- 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
- E21B21/062—Arrangements for treating drilling fluids outside the borehole by mixing components
-
- 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
- C09K8/02—Well-drilling compositions
- C09K8/03—Specific additives for general use in well-drilling compositions
- C09K8/035—Organic additives
-
- 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
- C09K8/02—Well-drilling compositions
- C09K8/03—Specific additives for general use in well-drilling 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
- C09K8/514—Compositions based on water or polar solvents containing organic compounds macromolecular compounds of natural origin, e.g. polysaccharides, cellulose
-
- 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 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
- 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
- E21B33/138—Plastering the borehole wall; Injecting into the formation
-
- 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
- C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
- C09K2208/08—Fiber-containing well treatment fluids
Definitions
- the present invention relates to an additive for drilling fluids. More specifically, the additive of the present invention is intended to seal the walls of drilled boreholes to prevent or at least limit lost circulation of drilling fluid.
- Drilling for oil, gas or geothermal wells usually occurs in a depth of thousands of meters. Such wells are drilled using a drill bit that is connected to a drill string that extends up to the surface.
- the drill string comprises a plurality of pipes, also known as casings, that are secured end to end.
- the drilling operation will form a borehole in the formation and more pipes are added to the drill string as the drilling operation continues.
- a drilling fluid such as drilling mud, is pumped down the drill string to the drill bit and is then circulated back up the annulus between the borehole and the drill string.
- the circulating drilling fluid will carry any drill cuttings from the drill bit up to the surface.
- the drill cuttings are typically removed from the drilling fluid at the surface and the drilling fluid is recirculated through the borehole.
- a further function of the drilling fluid is to provide a hydrostatic head that counters the pressure of the drilling gas or oil in the reservoir. Drilling mud pressure is usually maintained above formation pressure to prevent the reservoir fluid from flowing into borehole, which can cause well blowout conditions.
- a drilling fluid additive comprising a blend of cellulosic fibres, wherein the particle size distribution of the blend of cellulosic fibres is such that between 40% and 60% of the cellulosic fibres have a particle size of less than 75 microns.
- the blend of cellulosic fibers comprises hardwood fibres. More preferably, the hardwood fibres comprise teak wood fibres. As would be appreciated by a person skilled in the art, teak (Tectona grandis) is a hardwood tree species in the family Lamiaceae.
- blend of cellulosic fibres will be understood to refer to a mixture of cellulosic fibres with different particles sizes or particles size fractions.
- the blend of cellulosic fibres comprises fibres that have a modulus of rupture of at least 80 MPa.
- at least 90% of the cellulosic fibres have a modulus of rupture of at least 80 MPa.
- the particle size distribution of the blend of cellulosic fibres is such that between 40% and 60% of the fibres have a particle size of between 75 microns and 250 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 15% and 24% of the fibres have a particle size of less than 40 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 17% and 22% of the fibres have a particle size of less than 40 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 12% and 20% of the fibres have a particle size of between 40 microns and 50 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 14% and 18% of the fibres have a particle size of between 40 microns and 50 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 40% and 60% of the fibres have a particle size of less than 60 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 45% and 57% of the fibres have a particle size of less than 60 microns
- the particle size distribution of the blend of cellulosic fibres is such that between 24% and 36% of the fibres have a particle size of between 80 microns and 160 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 26% and 33% of the fibres have a particle size of between 80 microns and 160 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 29% and 44% of the fibres have a particle size of between 80 microns and 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 33% and 41% of the fibres have a particle size of between 80 microns and 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 8% and 12% of the fibres have a particle size of between 160 microns and 350 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 9% and 11% of the fibres have a particle size of between 160 microns and 350 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 3% and 5% of the fibres have a particle size above 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 3.5% and 4.5% of the fibres have a particle size above 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that less than 1% of the fibres have a particle size above 350 microns.
- At least 80% of the drilling fluid additive comprises the blend of cellulosic fibres.
- at least 82% of the drilling fluid additive comprises the blend of cellulosic fibres.
- at least 84% of the drilling fluid additive comprises the blend of cellulosic fibres.
- at least 86% of the drilling fluid additive comprises the blend of cellulosic fibres.
- at least 88% of the drilling fluid additive comprises the blend of cellulosic fibres.
- at least 90% of the drilling fluid additive comprises the blend of cellulosic fibres.
- At least 92% of the drilling fluid additive comprises the blend of cellulosic fibres. In one form of the present invention, at least 94% of the drilling fluid additive comprises the blend of cellulosic fibres. In one form of the present invention, at least 96% of the drilling fluid additive comprises the blend of cellulosic fibres. In one form of the present invention, at least 98% of the drilling fluid additive comprises the blend of cellulosic fibres.
- a drilling fluid that comprises the drilling fluid additive of the present invention.
- the concentration of the drilling fluid additive in the drilling fluid is at least 1 pounds per barrel of oil (Ibs/bbl). In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 2 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 3 Ibm/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 4 Ibm/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 5 Ibs/bbl.
- the concentration of the drilling fluid additive in the drilling fluid is at least 6 Ib/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 7 Ibm/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 8 Ibm/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 9 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 10 Ibs/bbl.
- the concentration of the drilling fluid additive in the drilling fluid is between 1 Ibs/bbl and 50 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is between 5 Ibs/bbl and 50 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is between 10 Ibs/bbl and 50 Ibs/bbl.
- a method of treating a borehole that extends into a formation comprising the steps of: providing a drilling fluid according to the second broad aspect of the present invention; and circulating the drilling fluid through the borehole to form a substantially impermeable layer on a wall surface of the borehole.
- the substantially impermeable layer comprises a matrix of the cellulosic fibres.
- the matrix further comprises solid particles from the formation.
- a lost circulation pill comprising drilling fluid additive according to the first aspect of the present invention.
- a method of sealing fractures that extend into a formation from a borehole that extends through the formation comprising the steps of: providing a lost circulation pill according to the fourth aspect of the present invention; and circulating the pill through the borehole to form a substantially impermeable layer on a wall surface of the borehole.
- the substantially impermeable layer comprises a matrix of the cellulosic fibres.
- the matrix further comprises solid particles from the formation.
- a formation that includes a borehole through which a lost circulation pill according to the fourth aspect of the present invention has been circulated, a fracture that extends into the formation from the borehole, and a substantially impermeable seal that is formed in the fracture and that includes a matrix of the lost circulation material from the pills drilling fluid additive.
- Figure 1 is a cross-section of a borehole in a formation where a drilling fluid containing the drilling fluid additive is circulated through the borehole;
- Figure 2 is a cross-section of a borehole in a formation where the cellulosic fibres from a drilling fluid additive of the present invention has formed a layer of wall filter cake;
- Figure 3 is a cross-section of a borehole in a formation that includes fractures that are each sealed by a matrix of the cellulosic fibres from a drilling fluid additive of the present invention.
- Figure 4 is a flow chart of a method of sealing fractures in a formation that extends from a borehole in the formation;
- Figure 5 shows the results of a particle size analysis performed on the drilling fluid additive of the present invention
- Figure 6 shows the results of a particle size analysis performed on a comparable drilling fluid additive
- Figure 7 shows the results of a permeability plugging test conducted at 5000 psi using the drilling fluid additive of the present invention
- Figure 8 shows the results of a permeability plugging test conducted at 8000 psi using the drilling fluid additive of the present invention
- Figure 9 shows the results of a fluid invasion test using the drilling fluid additive of the present invention.
- the present invention relates broadly to a drilling fluid additive that is intended to reduce the loss of drilling fluid to the surrounding subterranean structure.
- the drilling fluid additive comprises a blend of cellulosic fibres with a particular particle size distribution. When incorporated into a drilling fluid, the cellulosic fibres will form a barrier across pores or fractures in the surrounding subterranean structure to form a seal. This barrier has been found to limit the loss of the drilling fluid to the surrounding subterranean structure.
- the blend of cellulosic fibres contains a particular blend of cellulosic fibres of different particle sizes.
- the inventors have found that the blend of cellulosic fibres needs to contain a specific amount of particles below a particular particle size to form a sufficiently impermeable layer on the walls of the borehole to substantially seal the borehole.
- the inventors have found that a minimum amount of particles in a number of different particle size ranges will increase the seal.
- the inventors believe that both an adequate amount of particles below a certain particle size and above a certain particle size are required to form the seal.
- the cellulosic fibres are preferably derived from hardwood sources.
- the inventors have found that hardwood fibres are particularly useful for use in the drilling fluid additive of the present invention as they demonstrate particular physical properties.
- such fibres are both flexible and strong. This allows the fibres to intertwine and penetrate the pores and/or fractures, whilst being able to support the build-up of a fibrous mat that is capable of withstanding significant hydrostatic pressure from the fluids encountered in the well bore.
- the cellulosic fibres are teak wood fibres.
- the blend of cellulosic fibres comprises fibres that have a modulus of rupture of at least 80 MPa. In one embodiment, the blend of cellulosic fibres comprises fibres that have a modulus of rupture of at least 85 MPa. In one embodiment, the blend of cellulosic fibres comprises fibres that have a modulus of rupture of at least 90 MPa. In one embodiment, the blend of cellulosic fibres comprises fibres that have a modulus of rupture of at least 95 MPa.
- cellulosic fibres are biodegradable. This provides an environmentally friendly solution as the additive does not rely on long chain polymers which do not readily decompose.
- a further advantage is that the formed fibrous mat does not irreversibly seal the surrounding formation. Whilst some prior art technologies utilise seals that may be reversed, this will typically require the addition of a further chemical agent, for example and acid, to reverse the seal. As the cellulosic fibres will naturally degrade over time, the need to introduce a further chemical agent is avoided.
- the blend of cellulosic fibres comprises two distinct distributions of fibres lengths, a short fibre component and a long fibre component.
- the short fibre component has an average particles size less than 75 microns.
- the short fibre component is present at an amount of between 40% and 60% of the drilling fluid additive as a whole. In one embodiment at least 90% of the fibres in the short fibre component have a particles size less than 75 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 15% and 24% of the fibres have a particle size of less than 40 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 17% and 22% of the fibres have a particle size of less than 40 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 0.10% - 0.20% of the fibres have a particle size of between 8 microns and 15 microns. In one form of the present invention, the particle size distribution of the blend of cellulosic fibres is such that between 0.10% - 0.15% of the fibres have a particle size of between 8 microns and 15 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 15.50% - 23.40% of the fibres have a particle size of between 15 microns and 40 microns. In one form of the present invention, the particle size distribution of the blend of cellulosic fibres is such that between 17.50% - 21.50% of the fibres have a particle size of between 15 microns and 40 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 12% and 20% of the fibres have a particle size of between 40 microns and 50 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 14% and 18% of the fibres have a particle size of between 40 microns and 50 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 12.60% - 19.10%of the fibres have a particle size of between 50 microns and 60 microns. In one form of the present invention, the particle size distribution of the blend of cellulosic fibres is such that between 14.20% - 17.50% of the fibres have a particle size of between 50 microns and 60 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 40% and 62% of the fibres have a particle size of less than 60 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 45% and 57% of the fibres have a particle size of less than 60 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 6.60% - 10.00% of the fibres have a particle size of between 60 microns and 80 microns. In one form of the present invention, the particle size distribution of the blend of cellulosic fibres is such that between 7.40% - 9.20% of the fibres have a particle size of between 60 microns and 80 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 13.30% - 20.10% of the fibres have a particle size of between 80 microns and 130 microns. In one form of the present invention, the particle size distribution of the blend of cellulosic fibres is such that between 15.00% - 18.40% of the fibres have a particle size of between 80 microns and 130 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 24% and 36% of the fibres have a particle size of between 80 microns and 160 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 26% and 33% of the fibres have a particle size of between 80 microns and 160 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 29% and 44% of the fibres have a particle size of between 80 microns and 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 33% and 41% of the fibres have a particle size of between 80 microns and 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 10.60% - 15.90% of the fibres have a particle size of between 130 microns and 160 microns. In one form of the present invention, the particle size distribution of the blend of cellulosic fibres is such that between 11.90% - 14.60% of the fibres have a particle size of between 130 microns and 160 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 8% and 12% of the fibres have a particle size of between 160 microns and 350 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 9% and 11% of the fibres have a particle size of between 160 microns and 350 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 3% and 5% of the fibres have a particle size above 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that between 3.5 and 4.5% of the fibres have a particle size above 220 microns.
- the particle size distribution of the blend of cellulosic fibres is such that less than 1% of the fibres have a particle size above 350 microns.
- particle size is defined as the dimension of a particle which is determined by a sieve size analysis according to the Sieving Test described in greater detail herein. A sample of particles is sieved as described, and the results are recorded. The results of such a sieve size analysis sufficiently define the size of the particles for the purposes of the present invention. The results of the sieve analysis may be expressed by two equivalent conventions in terms of the characteristics of the sieves used. [0056] One way to express the size of the particles is in terms of the size of the openings in the sieves.
- a particle that is retained on a sieve with 75 micron openings is considered to have a particle size greater than or equal to 75 microns for the purposes of the present invention.
- a particle that passes through a sieve with 90 micron openings and is retained on a sieve with 75 micron openings is considered to have a particle size between 75 and 90 microns.
- a particle that passes through a sieve with 75 microns is considered to have a particle size less than 75 microns.
- the other way to express the size of the particles in terms of the results of a sieving analysis is in terms of the designation used for the sieves. Two main scales are used to designate the mesh sizes, the US Sieve Series and Tyler Mesh Size.
- the sieving test may determine the size of only certain dimensions of a specific particle.
- the fibres may pass vertically through the apertures of the mesh, resulting in particles with larger cross sections passing through the mesh. Because of this, the test results are generally expressed in terms of the percentage of particles, by weight, which will ordinarily pass through a sieve of one dimension and be retained on a sieve of a second dimension. Whilst the major proportion of the fibres in the cellulosic fibre blend with fall within the ranges disclosed, it should be understood that any the blend of fibres will comprises a broad distribution of fibre sizes.
- no more than about 20%, more preferably no more than about 10%, and most preferably no more than about 5% by weight of the particles should have any dimension larger than the sieve they have passed through.
- the specific particle size distributions described above can be prepared by any suitable method.
- the specific particle size distributions can be prepared, at least in relatively small amounts by a sieving operation.
- cellulose fibres undergo one or more size reduction steps to produce a blend of cellulosic fibres with an appropriate particle size distribution.
- the one or more size reduction steps include one or more mechanical size reductions step.
- at least one of the size reduction step is a grinding step.
- a size reductions step is performed using a hammer mill. Additionally or alternatively, a size reduction step is performed using a disc mill.
- one or more sizing steps are used to separate out fractions of the cellulosic fibres that require additional size reduction.
- a cyclonic classification apparatus is used in the one or more sizing steps.
- the most effective way in which to achieve the desired particle size distribution is to produce fractions of fibres within a particular particle size range.
- Means for bulk classification of fibres may be used initially to produce rough fractions which may then be further separated into further size fractions downstream. The fraction may then be appropriately blended to produce an additive with the required particle size distribution.
- the present invention further relates to a drilling fluid that comprises a drilling fluid additive as described above.
- the concentration of the drilling fluid additive in the drilling fluid is at least 1 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 2 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 3 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 4 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 5 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 6 Ibs/bbl.
- the concentration of the drilling fluid additive in the drilling fluid is at least 7 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 8 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 9 Ibs/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is at least 10 Ibs/bbl.
- the concentration of the drilling fluid additive in the drilling fluid is between 1 Ibm/bbl and 50 Ibm/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is between 5 Ibm/bbl and 50 Ibm/bbl. In one form of the present invention, the concentration of the drilling fluid additive in the drilling fluid is between 10 Ibm/bbl and 50 Ibm/bbl.
- the drilling fluid is a liquid drilling fluid.
- the drilling fluid may be a water-based drilling fluid, an oil-based drilling fluid, or a synthetic-based drilling fluid.
- the drilling fluid is a water or oil-based drilling mud.
- the drilling fluid comprises hydrated clay. It is preferred that the clay comprises bentonite. Alternatively, the drilling fluid comprises a polymer
- the present further relates to a method of drilling a well borehole in a subterranean formation.
- the method generally comprises the steps of: providing a drilling fluid additive comprising a blend of cellulosic fibres, mixing the sealant with a drilling fluid; and pumping the sealant and drilling fluid mixture down the borehole to seal the borehole pores and fractures.
- the drilling fluid 30 to which the drilling fluid additive of the present invention has been added is pumped down a well borehole 40 that extends through a formation.
- the drilling fluid 30 is pumped down the borehole 40 through a drill string 41 and a drill bit 42 that is attached to the drill string 41 , and is then circulated back up an annulus 43 between a wall 44 of the borehole 40 and the drill string 41.
- the drilling fluid 30 which is circulated back up the annulus 43 also includes cuttings and other fine solid particles.
- the overbalance pressure i.e.
- the extent to which the hydrostatic pressure of the drilling fluid 30 in the borehole 30 exceeds the pressure of the formation through which the borehole 30 is being drilled) of the drilling fluid 30 results in the fibres of the additive combining with the cuttings and other fine solid particles in the drilling fluid 30 to form an impermeable layer 45 comprising a thin wall/filter cake 46 that lines the wall surface 47 of the borehole 40.
- Figure 2 depicts the borehole/wellbore 40 passing through a sand formation 50.
- Drilling fluid 30 in the borehole 40 can be lost through the pores in the formation 50.
- the formation 50 is a sand formation, it is not as strong or as stable as rock formations.
- the impermeable layer 45 on the wall surface 47 inhibits the drilling fluid 30 in the borehole 40 from being lost in the porous formation 50.
- it strengthens and stabilises the borehole 40 to inhibit the wall 44 of the borehole 40 from collapsing.
- the fibres form an impermeable matrix in the layer of wall filter cake 46. The large fibres first agglomerate over the pores or fractures to form a loose fiberous mat.
- the smaller fibres then agglomerate on the fiberous mat to reduce the spaces between the large fibres in the matrix.
- the wall cake 46 matrix becomes denser and the permeability reduces.
- the drill cuttings and other fine solid colloidal particles in the drilling fluid 30 further enhance the matrix by filling the spaces between the fibres and assist in reducing the wall cake 46 permeability.
- the wall cake 46 is then able to substantially plug or seal the porous/fractured formation 50 and is thereby able to substantially prevent drilling fluid 30 in the borehole 40 from entering the formation 50 and being lost.
- Figure 3 depicts the borehole/wellbore 40 passing through a fractured limestone formation 60.
- the formation 60 includes a plurality of large fractures 51 that extend into the formation 50 from the borehole 40.
- Drilling fluid in the borehole 40 can be lost through the fractures 51 resulting in lost circulation of the drilling fluid.
- the lost circulation material 11 will be pumped into the fractures 51 where it forms a seal 52 that includes an impermeable matrix of cellulosic fibres and cuttings.
- the seals 52 are able to substantially plug or seal the large fractures 51 and are thereby able to substantially stop drilling fluid in the borehole 40 from entering the formation 50 through the fractures 51 and being lost.
- the above-described steps comprise a method 70 of treating a borehole that extends into a formation.
- the inclusion of both the small and large fibres in the drilling fluid additive makes the drilling fluid additive particularly suitable for use in sealing a producing formation such that severe lost circulation in the formation is eliminated or at least reduced.
- the formation zone is able to produce an amount of oil or gas which is the same as or more than that which was originally intended.
- a drilling fluid additive in accordance with the present invention was prepared (New Fracseal) and a particle size analysis was performed. The results of the particle size analysis are shown in Figure 5.
- a drilling fluid additive was prepared in accordance with the method taught in AU 72159/01 (Reg. Fracseal).
- a particles size analysis of this reference drilling fluid additive is shown in Figure 6.
- the target average particle size was mesh 80 to mesh 325. As can be seen from the particle size distribution curve, this results in a fairly normal distribution of particle sizes with a mean particles size of approximately 80 urn and a fairly large standard deviation.
- the particles size distribution of the New Fracseal sample exhibits multiple distinct modes that is indicative of a blend of separate particle size factions. It is clears that there is significant portion of the particles in a range of 15-50 urn and another significant portion of the particles in a range of 80-160 urn
- API American Petroleum Institute
- Recommended Practice 13B-1 (RP 13B- 1) establishes recommended practices for field testing water-based drilling fluids using a standard API filter press.
- a standard API filter press was modified to replace the filter paper with a 20/40 gravel sand to emulate a down hole formation.
- 20/40 sand a 2 - 2.5cm invasion across gravel sand is generally accepted as the bench mark for a good wellbore stability.
- the following test procedure was adopted: i. The cell was filled with 20/40 sand/gravel until approximately half full. ii. The sand bed was levelled by manually shaking the cell. iii.
- the drilling mud sample was gently poured into the cell up to the upper mark for maximum fluid level. iv.
- the cell was placed into its support and the top cap was secured with the “T- screw”.
- a dry graduated cylinder is placed below the cell.
- the relief valve was closed and the regulator was slowly adjusted to a pressure of 100 psi. The test period begins at the time of pressure application. vi.
- the fluid was allowed to filtrate through the sand for 10 mins.
- the drilling fluid additive of the present invention will act to seal the borehole to limit the loss of the drilling fluid. Whilst this is advantageous during the drilling process, the introduction of the additive to the formation may also impact the flow properties of the formation at the intended production zone.
- a series of return tests were undertaken to determine any detrimental impact the drilling fluid of the present invention had on the formation.
- the testing methodology employed was as follows: i. Prepare 350ml of pre-hydrated bentonite. ii. Mixture of a predetermined amount of a drilling fluid additive with the prepared bentonite. iii. Fill an API cylinder cell (without any filter paper) with 20/40 gravel pack sand to about 1/3 of the cylinder. iv. Pour the mixed cellulose fiber or bentonite into the cylinder. v. After the cylinder is closed then apply pressure of 200 psi to the cylinder. vi. After 30 minutes the cylinder was opened and excess drilling fluid was discarded leaving the formed filter cake vii.
- a portion of 20/40 gravel sand was inserted into the cylinder and a 40 micron mesh screen was inserted into the cylinder viii.
- the top of the cylinder was sealed with a lid comprising a single outlet ix. Water was pumped into the bottom of the cylinder at a pressure of 10 psi and allowed to flow through the sand, the filter cake and the outlet port
- the tests showed a return permeability of 100%.
- the test showed that the under positive pressure, the drilling fluid additive forms a filter cake across the gravel pack sand. Once the positive pressure is reversed, the formed filter cake was removed from the gravel pack sand, allowing the reverse flow of liquid through the gravel pack sand.
- the results of the return permeability measurements indicated that the filter cake formed did not have any detrimental effects on the flow properties of the formation.
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Abstract
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Application Number | Priority Date | Filing Date | Title |
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AU2019904117A AU2019904117A0 (en) | 2019-10-31 | High Pressure Drilling Fluid Additives | |
PCT/IB2020/059914 WO2021084387A1 (en) | 2019-10-31 | 2020-10-22 | High pressure drilling fluid additive |
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EP4051751A4 EP4051751A4 (en) | 2023-11-15 |
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US5861362A (en) * | 1992-01-06 | 1999-01-19 | Blue Diamond Growers | Almond shell additive and method of inhibiting sticking in wells |
AU7215901A (en) * | 2001-09-18 | 2003-03-20 | Pt. Obm Drilchem | Method of sealing pores and fractures inside boreholes with biodegradable micronised cellulose fibers and apparatus for making the micronised cellulose fibers |
US7284611B2 (en) * | 2004-11-05 | 2007-10-23 | Halliburton Energy Services, Inc. | Methods and compositions for controlling lost circulation in subterranean operations |
US8043997B2 (en) * | 2008-02-29 | 2011-10-25 | Halliburton Energy Services Inc. | Lost circulation material formulation and method of use |
EP2261458A1 (en) * | 2009-06-05 | 2010-12-15 | Services Pétroliers Schlumberger | Engineered fibres for well treatments |
US20150072901A1 (en) * | 2013-09-09 | 2015-03-12 | Clearwater International Llc | Lost circulation and fluid loss materials containing guar chaff and methods for making and using same |
WO2016019415A1 (en) * | 2014-08-05 | 2016-02-11 | Ryanto Husodo | Drilling fluid additive |
US10689564B2 (en) * | 2015-11-23 | 2020-06-23 | Schlumberger Technology Corporation | Fluids containing cellulose fibers and cellulose nanoparticles for oilfield applications |
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2020
- 2020-10-22 CN CN202080077660.3A patent/CN115038772A/en active Pending
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