US20080190610A1 - Fracture Clean up Method - Google Patents
Fracture Clean up Method Download PDFInfo
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- US20080190610A1 US20080190610A1 US12/029,995 US2999508A US2008190610A1 US 20080190610 A1 US20080190610 A1 US 20080190610A1 US 2999508 A US2999508 A US 2999508A US 2008190610 A1 US2008190610 A1 US 2008190610A1
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- accordance
- particulate
- fracture
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- copolymers
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- 238000000034 method Methods 0.000 title claims abstract description 56
- 239000012530 fluid Substances 0.000 claims abstract description 21
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 19
- 239000002253 acid Substances 0.000 claims abstract description 11
- 239000000126 substance Substances 0.000 claims abstract description 7
- 239000002243 precursor Substances 0.000 claims abstract description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 29
- 239000002245 particle Substances 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 15
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 14
- 229920001577 copolymer Polymers 0.000 claims description 13
- 239000004800 polyvinyl chloride Substances 0.000 claims description 13
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 13
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 8
- 235000019270 ammonium chloride Nutrition 0.000 claims description 7
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 3
- 239000000460 chlorine Substances 0.000 claims description 3
- 229910052801 chlorine Inorganic materials 0.000 claims description 3
- 150000007522 mineralic acids Chemical class 0.000 claims 2
- 238000005530 etching Methods 0.000 abstract description 3
- 238000004140 cleaning Methods 0.000 abstract description 2
- 238000005086 pumping Methods 0.000 abstract description 2
- 239000008398 formation water Substances 0.000 abstract 1
- 229920000642 polymer Polymers 0.000 description 31
- 238000005755 formation reaction Methods 0.000 description 16
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 16
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 16
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 13
- 239000000463 material Substances 0.000 description 9
- 239000012065 filter cake Substances 0.000 description 8
- 239000000178 monomer Substances 0.000 description 7
- 150000002978 peroxides Chemical class 0.000 description 7
- 230000008901 benefit Effects 0.000 description 6
- 230000006378 damage Effects 0.000 description 6
- 229930195733 hydrocarbon Natural products 0.000 description 6
- 150000002430 hydrocarbons Chemical class 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000003921 oil Substances 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 150000002484 inorganic compounds Chemical class 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000000518 rheometry Methods 0.000 description 2
- 230000000638 stimulation Effects 0.000 description 2
- 238000007669 thermal treatment Methods 0.000 description 2
- 238000009827 uniform distribution Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- MIMUSZHMZBJBPO-UHFFFAOYSA-N 6-methoxy-8-nitroquinoline Chemical compound N1=CC=CC2=CC(OC)=CC([N+]([O-])=O)=C21 MIMUSZHMZBJBPO-UHFFFAOYSA-N 0.000 description 1
- 229910021532 Calcite Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 244000007835 Cyamopsis tetragonoloba Species 0.000 description 1
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- KVBCYCWRDBDGBG-UHFFFAOYSA-N azane;dihydrofluoride Chemical group [NH4+].F.[F-] KVBCYCWRDBDGBG-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 239000010779 crude oil Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 150000002222 fluorine compounds Chemical group 0.000 description 1
- 230000009477 glass transition Effects 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 235000010977 hydroxypropyl cellulose Nutrition 0.000 description 1
- 239000001863 hydroxypropyl cellulose Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 150000001451 organic peroxides Chemical class 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 229920000747 poly(lactic acid) Polymers 0.000 description 1
- 239000004626 polylactic acid Substances 0.000 description 1
- 229920002717 polyvinylpyridine Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- GRJJQCWNZGRKAU-UHFFFAOYSA-N pyridin-1-ium;fluoride Chemical group F.C1=CC=NC=C1 GRJJQCWNZGRKAU-UHFFFAOYSA-N 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011973 solid acid Substances 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
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
-
- 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
- C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
-
- 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
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/70—Compositions for forming crevices or fractures characterised by their form or by the form of their components, e.g. foams
-
- 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
- C09K8/60—Compositions for stimulating production by acting on the underground formation
- C09K8/62—Compositions for forming crevices or fractures
- C09K8/72—Eroding chemicals, e.g. acids
-
- 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
- E21B37/00—Methods or apparatus for cleaning boreholes or wells
Definitions
- This invention relates to the oil and gas industry, and in particular, to methods of oil and gas production, and can be applied to improve hydrocarbon recovery from a fractured subterranean reservoir due to fracture clean up.
- Some methods are known where low-molecular oxidizers (persulfates/peroxides of metals or ammonium) or organic peroxides are applied as gel breaker. These oxidizers and peroxides are effective up to 120° C. Sometimes these breakers are poorly compatible with the fracturing fluid or with resin coated proppant.
- Some methods describe treatment of near-wellbore zone with hydrochloric acid pumped. This method is not adapted for removal of gel and filter cake damage from propped fractures.
- organic acid precursor e.g., polylactic acid
- the solid acid precursor can make up to 10% by weight of the total proppant mass. This invention is the most similar to the disclosed invention.
- compositions of the present invention are described herein as comprising certain materials, it should be understood that the composition could optionally comprise two or more chemically different materials.
- the composition can also comprise some components other than the ones already cited.
- each numerical value should be read once as modified by the term “about” (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context.
- a concentration range listed or described as being useful, suitable, or the like is intended that any and every concentration within the range, including the end points, is to be considered as having been stated.
- “a range of from 1 to 10” is to be read as indicating each and every possible number along the continuum between about 1 and about 10.
- the current invention describes a method for cleaning up a propped fracture by aiding the breakdown and removal of gel and gel residue from the fracture.
- the technical benefit of this method is the improved fluid mobility into and inside the propped fracture and therefore enhancement of hydrocarbon production from the fracture.
- the fracturing fluid carries proppant and particulate into the propped fracture; the said particulate under formation temperature releases a substance that reacts with the formation fluid and produces hydrochloric or etching acid.
- the preferable embodiment of this patent uses the particles of polyvinyl chloride or polyvinylden chloride or their copolymers comprising monomers of vinyl chloride or vinylden chloride, as well as their chlorinate analogs.
- Another variant is the use of material granulated and encapsulated into oil-dissolving coating; the said material is ammonium chloride or fluoride, ammonium difluoride, pyridine fluoride, and fluoride-bearing polymers, e.g., fluoride of polyvinylpyridine.
- the usual size of polymer particulate varies from 0.1 microns to 10 mm.
- the preferable amount of vinyl chloride is from 0.1% to 99.9% wt., and the content of chloride in the polymer is from 0.01% to 85% wt.
- the proportion of polymeric particulate as a percentage of proppant mass varies from 0.1% to 99.9%.
- the method is based on using the substances which release hydrochloride under conditions of the formation temperature and in a water-oil medium; the produced hydrogen chloride destroys the polymer gel and dissolves the gel residue, typically filter cake.
- the disclosed method is based on using a new material for this technique (preferably, polyvinylchloride or co-polymers).
- FIG. 1 shows the diagram that illustrate a loss of polymer mass over the time of the thermal treatment.
- the yield of hydrogen chloride from the said polymeric material is a long-term process (tens of days). A long time interval facilitates more uniform distribution of produced hydrochloric acid over the fracture volume and ensures more complete breaking of polymer gel.
- the particulate of polymer based on vinylchloride monomer releases hydrogen chloride at elevated temperatures (130 . . . 200° C.), where most commercially available peroxide breakers lose effectiveness (e.g., peroxide and persulfate of metal or ammonium).
- the polymer particles with vinylchloride monomers do not react with resin coated proppant (RCP) or reduce the strength of the proppant packing that can lead to a reduction of fracture width.
- RCP resin coated proppant
- the polymer particles with vinylchloride monomers are non-reactive with the fracturing fluid during the fracturing process and fracture closure; the particulate does not affect the rheology of fracturing fluids or solids transport properties.
- Hydrogen chloride released from particulates with vinylchloride monomers can dissolve a carbonate rock and create microchannels in the formation. This creates a divaricated system of drainage and improves the hydrocarbon flow towards the wellbore.
- Hydrogen chloride released from polymer particulates can dissolve the filter cake formed during filtration on gel by the rock matrix.
- a new method of conducting of hydraulic fracturing is disclosed in the following claims; according to this method, proppant is delivered to the fracture with a mixture polymer particles (polyvinylchloride or copolymers of vinylchloride), wherein the main proppant and polymeric particulate can be mixed before the job or on-the-fly and then delivered to the subterranean formation.
- a mixture polymer particles polyvinylchloride or copolymers of vinylchloride
- the main proppant and polymeric particulate can be mixed before the job or on-the-fly and then delivered to the subterranean formation.
- the polymeric material produces hydrogen chloride that destroys the network of intermolecular cross-links in the polymer gel; the said cross-linked network is formed due to intermolecular bonds between hydroxyl groups of polymer gel and ions of multivalent metals (the cross-linking agents).
- the produced hydrogen chloride breaks the gel and improves the water solubility of polymer components suspended in the fracturing fluid; this reduces the viscosity of fracturing solution.
- the said factors facilitate a more complete cleanup of polymer gel from the fracture and improve the fracture permeability.
- the method ensures dissolving of the filer cake and formation of micro channels in the formation; the later creates a divaricated system of drainage and facilitates the flow of hydrocarbons towards the wellbore.
- the molar concentration of vinylchloride monomer units in a copolymer varies from about 0.1% to about 99.9%.
- the copolymer may include plasticizers, thermostability agents, and organic and inorganic compounds.
- organic or inorganic compounds can be used for the same purpose if they produce hydrogen chloride or hydrogen fluoride under formation conditions; the released hydrogen chloride or hydrogen fluoride combine in water to form hydrochloric acid or etching acid.
- the particles of polymeric material can be employed during the entire operation of hydrofracturing or at the final stages.
- the release of hydrogen chloride by polyvinylchloride was proven by the following experiment.
- a sample of polyvinylchloride was stored for several days at a high temperature (110° C.) in crude oil.
- the polyvinylchloride sample initially had a glass transition temperature of 56° C. and crystalline degree equal to 12%. There was no plasticizer in the composition.
- the yield of hydrogen chloride from the said polymeric material is a long-run process (tens of days). A long time interval facilitates more uniform distribution of produced hydrochloric acid over the fracture volume and ensures more complete breaking of polymer gel.
- the particulate of polymer based on vinylchloride monomer effectively releases hydrogen chloride at elevated temperature of formation (130 . . . 200° C.), when most of commercially available peroxide gel breakers (e.g., peroxide and persulfate of metal or ammonium) fail.
- peroxide gel breakers e.g., peroxide and persulfate of metal or ammonium
- the polymer particles with vinylchloride monomers does not react with components of resin coated proppant and therefore should not damage the proppant pack strength which can lead to a reduction of fracture width.
- the polymer particles with vinylchloride monomers do not react with fracturing fluids during any stage of the fracturing process or during fracture closure; the particulate will not affect the rheology of fracturing fluid or proppant transport properties.
- Hydrogen chloride or hydrogen fluoride released from particulates can dissolve a carbonate rock and create micro channels in the formation. This creates a divaricated system of drainage and facilitates the flow of hydrocarbons towards the wellbore.
- Hydrogen chloride or hydrogen fluoride released from polymer particulates is capable of filter cake removal because these particles will be trapped inside the fracture, near the fracture surface.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Geology (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Geochemistry & Mineralogy (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Cleaning In General (AREA)
- Cleaning By Liquid Or Steam (AREA)
- Detergent Compositions (AREA)
Abstract
Methods including the pumping of fracturing fluid carrying proppant. Simultaneously particulate is pumped made of substance that under subterranean temperature releases hydrochloric or etching acid precursor, wherein the said acid precursor reacts with the formation water and produces acid. The methods stimulate the inflow of formation fluid towards the well due to cleaning of the surface of hydrofracture and due to growth of its area.
Description
- This application claims foreign priority benefits to Russian Patent Application No. 2007105188, filed on Feb. 13, 2007.
- The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
- This invention relates to the oil and gas industry, and in particular, to methods of oil and gas production, and can be applied to improve hydrocarbon recovery from a fractured subterranean reservoir due to fracture clean up.
- The method of hydraulic fracturing of oil-bearing formation is an efficient method for stimulation of oil/gas production from a well. The goal of hydraulic fracturing is to pump a fluid under the pressure and rate sufficient for cracking the formation of the reservoir; this creates two fractures on opposite sides of wellbore traveling in opposite directions. These large-scale fractures are required as conduits for draining of hydrocarbon fluids into the borehole; these conduits have a higher fluid conductivity than the formation itself. To prevent the fracture closing when the fluid pumping has ended, propping agents are delivered with the fluid into the fractures. This proppant particulate is carried into the formation by fracturing fluid with a required certain density and viscosity. The preferable variant of fracturing fluid is viscous solution of viscoelastic polymers (guar or hydroxypropylcellulose).
- The disadvantage of traditional fracturing methods is damaging the fracture with polymers and products of their decomposition. The residue of undamaged polymer stays in pores and considerably reduces fracture permeability. Research data shows that 45 to 75% of polymer remains in the fracture after an initial flowback period. To counteract this damage breakers are used to reduce gel viscosity and help remove concentrated polymer residues.
- Some methods are known where low-molecular oxidizers (persulfates/peroxides of metals or ammonium) or organic peroxides are applied as gel breaker. These oxidizers and peroxides are effective up to 120° C. Sometimes these breakers are poorly compatible with the fracturing fluid or with resin coated proppant.
- Some methods describe treatment of near-wellbore zone with hydrochloric acid pumped. This method is not adapted for removal of gel and filter cake damage from propped fractures.
- Other methods a method for acid treatment of the near-wellbore zone. A mixture of polyvinylchloride and ammonium bifluoride is thermally decomposed (due to in-situ ignition or impact of formation temperature) and produces acid. The resulting mixture of acids is used to break apart the colloidal sediments of ferrous oxide. This method has not been adapted for removal of gel and filter cake damage from propped fractures because is only used to treat the near-wellbore zone.
- Also known is a method of using acid to dissolve filter cake via a proppant with coating made of organic acid precursor (e.g., polylactic acid). This method may also be applied to aid with gel cleanup in gravel packs. The solid acid precursor can make up to 10% by weight of the total proppant mass. This invention is the most similar to the disclosed invention.
- There are many known methods for production improvement after stimulation, by removal of concentrated gel and filter cake from a propped fracture. Removal of gel damage is achieved by using of polymers that are capable to produce organic or nonorganic acids under subterranean conditions.
- At the outset, it should be noted that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system related and business related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
- The description and examples are presented solely for the purpose of illustrating the preferred embodiments of the invention and should not be construed as a limitation to the scope and applicability of the invention. While the compositions of the present invention are described herein as comprising certain materials, it should be understood that the composition could optionally comprise two or more chemically different materials. In addition, the composition can also comprise some components other than the ones already cited. In the summary of the invention and this detailed description, each numerical value should be read once as modified by the term “about” (unless already expressly so modified), and then read again as not so modified unless otherwise indicated in context. Also, in the summary of the invention and this detailed description, it should be understood that a concentration range listed or described as being useful, suitable, or the like, is intended that any and every concentration within the range, including the end points, is to be considered as having been stated. For example, “a range of from 1 to 10” is to be read as indicating each and every possible number along the continuum between about 1 and about 10. Thus, even if specific data points within the range, or even no data points within the range, are explicitly identified or refer to only a few specific, it is to be understood that inventors appreciate and understand that any and all data points within the range are to be considered to have been specified, and that inventors possession of the entire range and all points within the range.
- The current invention describes a method for cleaning up a propped fracture by aiding the breakdown and removal of gel and gel residue from the fracture.
- The technical benefit of this method is the improved fluid mobility into and inside the propped fracture and therefore enhancement of hydrocarbon production from the fracture.
- The said technical result is achieved by the following means: the fracturing fluid carries proppant and particulate into the propped fracture; the said particulate under formation temperature releases a substance that reacts with the formation fluid and produces hydrochloric or etching acid. The preferable embodiment of this patent uses the particles of polyvinyl chloride or polyvinylden chloride or their copolymers comprising monomers of vinyl chloride or vinylden chloride, as well as their chlorinate analogs. Another variant is the use of material granulated and encapsulated into oil-dissolving coating; the said material is ammonium chloride or fluoride, ammonium difluoride, pyridine fluoride, and fluoride-bearing polymers, e.g., fluoride of polyvinylpyridine. The usual size of polymer particulate varies from 0.1 microns to 10 mm. The preferable amount of vinyl chloride is from 0.1% to 99.9% wt., and the content of chloride in the polymer is from 0.01% to 85% wt. The proportion of polymeric particulate as a percentage of proppant mass varies from 0.1% to 99.9%.
- The method is based on using the substances which release hydrochloride under conditions of the formation temperature and in a water-oil medium; the produced hydrogen chloride destroys the polymer gel and dissolves the gel residue, typically filter cake. The disclosed method is based on using a new material for this technique (preferably, polyvinylchloride or co-polymers).
-
FIG. 1 shows the diagram that illustrate a loss of polymer mass over the time of the thermal treatment. - These new substances enable efficient cleanup of polymers typically used in hydraulic fracturing fluid by removal of concentrated gel and gel residues, such as filter cake. The advantages of using a polymer based on vinylchloride monomer in contrast to other methods of destruction the polymer gel in propped fractures are the following:
- 1. It is possible to reduce the concentration of costly gel breakers or abandon their use completely.
- 2. The yield of hydrogen chloride from the said polymeric material is a long-term process (tens of days). A long time interval facilitates more uniform distribution of produced hydrochloric acid over the fracture volume and ensures more complete breaking of polymer gel.
- 3. The particulate of polymer based on vinylchloride monomer releases hydrogen chloride at elevated temperatures (130 . . . 200° C.), where most commercially available peroxide breakers lose effectiveness (e.g., peroxide and persulfate of metal or ammonium).
- 4. Unlike common peroxide breakers, the polymer particles with vinylchloride monomers do not react with resin coated proppant (RCP) or reduce the strength of the proppant packing that can lead to a reduction of fracture width.
- 5. Unlike peroxide-type (persulfate-type) gel breakers, the polymer particles with vinylchloride monomers are non-reactive with the fracturing fluid during the fracturing process and fracture closure; the particulate does not affect the rheology of fracturing fluids or solids transport properties.
- 6. Hydrogen chloride released from particulates with vinylchloride monomers can dissolve a carbonate rock and create microchannels in the formation. This creates a divaricated system of drainage and improves the hydrocarbon flow towards the wellbore.
- 7. Hydrogen chloride released from polymer particulates can dissolve the filter cake formed during filtration on gel by the rock matrix.
- If other types of substances meet the conditions formulated in the independent claim of the invention formula, the advantages must be the same.
- A new method of conducting of hydraulic fracturing is disclosed in the following claims; according to this method, proppant is delivered to the fracture with a mixture polymer particles (polyvinylchloride or copolymers of vinylchloride), wherein the main proppant and polymeric particulate can be mixed before the job or on-the-fly and then delivered to the subterranean formation. Under the conditions of high subterranean temperature the polymeric material produces hydrogen chloride that destroys the network of intermolecular cross-links in the polymer gel; the said cross-linked network is formed due to intermolecular bonds between hydroxyl groups of polymer gel and ions of multivalent metals (the cross-linking agents). The produced hydrogen chloride breaks the gel and improves the water solubility of polymer components suspended in the fracturing fluid; this reduces the viscosity of fracturing solution. In general, the said factors facilitate a more complete cleanup of polymer gel from the fracture and improve the fracture permeability. In addition, the method ensures dissolving of the filer cake and formation of micro channels in the formation; the later creates a divaricated system of drainage and facilitates the flow of hydrocarbons towards the wellbore.
- The molar concentration of vinylchloride monomer units in a copolymer varies from about 0.1% to about 99.9%.
- The copolymer may include plasticizers, thermostability agents, and organic and inorganic compounds.
- Other organic or inorganic compounds can be used for the same purpose if they produce hydrogen chloride or hydrogen fluoride under formation conditions; the released hydrogen chloride or hydrogen fluoride combine in water to form hydrochloric acid or etching acid.
- In the method disclosed, the particles of polymeric material can be employed during the entire operation of hydrofracturing or at the final stages.
- The application feasibility of the method disclosed was proven by example using a polymer with vinylchloride monomers placed under conditions imitating the conditions of a producing oil well.
- The release of hydrogen chloride by polyvinylchloride was proven by the following experiment. A sample of polyvinylchloride was stored for several days at a high temperature (110° C.) in crude oil. The polyvinylchloride sample initially had a glass transition temperature of 56° C. and crystalline degree equal to 12%. There was no plasticizer in the composition.
- The evolution of sample weight during 1-32 days (showed on the abscissa axis) is plotted in the
FIG. 1 (the sample mass is on the left ordinate axis). It is apparent in this diagram that over the time of the thermal treatment there is loss of polymer mass showed on the left ordinate axis. The data of elementary analysis (carbon, hydrogen, chlorine) for initial sample and current state of degraded sample demonstrated that the mass loss of the polyvinylchloride correlates with the production of hydrogen chloride, showed on the right ordinate axis in gram - For example, a sample of polyvinylchloride with the initial mass of 0.100 kg was stored for the period of 19 days at temperature of 110° C. and produced 0.029 kg of hydrogen chloride, which is equivalent to 0.193 kg of hydrochloric acid with concentration 15%. This quantity of acid is enough to dissolve of 0.042 kg calcite rock, a typical component of carbonate formations.
- Advantages of the disclosed method in comparison to known at the art are the following:
- 1. It is possible to reduce the concentration or abandon completely the costly gel breakers.
- 2. The yield of hydrogen chloride from the said polymeric material is a long-run process (tens of days). A long time interval facilitates more uniform distribution of produced hydrochloric acid over the fracture volume and ensures more complete breaking of polymer gel.
- 3. The particulate of polymer based on vinylchloride monomer effectively releases hydrogen chloride at elevated temperature of formation (130 . . . 200° C.), when most of commercially available peroxide gel breakers (e.g., peroxide and persulfate of metal or ammonium) fail.
- 4. Unlike common peroxide-type gel breakers, the polymer particles with vinylchloride monomers does not react with components of resin coated proppant and therefore should not damage the proppant pack strength which can lead to a reduction of fracture width.
- 5. Unlike peroxide-type (persulfate-type) gel breakers, the polymer particles with vinylchloride monomers do not react with fracturing fluids during any stage of the fracturing process or during fracture closure; the particulate will not affect the rheology of fracturing fluid or proppant transport properties.
- 6. Hydrogen chloride or hydrogen fluoride released from particulates can dissolve a carbonate rock and create micro channels in the formation. This creates a divaricated system of drainage and facilitates the flow of hydrocarbons towards the wellbore.
- 7. Hydrogen chloride or hydrogen fluoride released from polymer particulates is capable of filter cake removal because these particles will be trapped inside the fracture, near the fracture surface.
Claims (24)
1. A method for fracture clean up that includes the delivery to the fracture of a substance capable to produce inorganic acid; the fracture is propped by a mixture of proppant and particulate that produces hydrochloric acid precursor under subterranean conditions and due to reaction with formation fluid.
2. The method in accordance with claim 1 , wherein the particulate is particles of polyvinylchloride and/or its copolymers.
3. The method in accordance with claim 1 , wherein the particulate is particles of polyvinyldenchloride.
4. The method in accordance with claim 3 , wherein the granulated ammonium chloride or fluoride coated with oil-soluble composition is employed.
5. The method in accordance with claim 1 , wherein the particulate is particles of copolymers of polyvinyldenchloride.
6. The method in accordance with claim 5 , wherein the granulated ammonium chloride or fluoride coated with oil-soluble composition is employed.
7. The method in accordance with claim 1 , wherein the particulate is particles of polyvinyldenchloride and its copolymers.
8. The method in accordance with claim 7 , wherein the granulated ammonium chloride or fluoride coated with oil-soluble composition is employed.
9. A method for fracture clean up that includes the delivery to the fracture of a substance capable to produce inorganic acid; the fracture is propped by a mixture of proppant and particulate that produces etchingc acid precursor under subterranean conditions and due to reaction with formation fluid.
10. The method in accordance with claim 9 , wherein the particulate is particles of polyvinylchloride and/or its copolymers.
11. The method in accordance with claim 9 , wherein the particulate is particles of polyvinyldenchloride.
12. The method in accordance with claim 11 , wherein the granulated ammonium chloride or fluoride coated with oil-soluble composition is employed.
13. The method in accordance with claim 9 , wherein the particulate is particles of copolymers of polyvinyldenchloride.
14. The method in accordance with claim 13 , wherein the granulated ammonium chloride or fluoride coated with oil-soluble composition is employed.
15. The method in accordance with claim 9 , wherein the particulate is particles of polyvinyldenchloride and its copolymers.
16. The method in accordance with claim 15 , wherein the granulated ammonium chloride or fluoride coated with oil-soluble composition is employed.
17. The method in accordance with 11 wherein the particulate size varies from 0.1 microns to 10 mm.
18. The method in accordance with 11 wherein the content of polyvinylchloride and polyvinyldenchloride in copolymers is from 0.1 wt. % to wt. 99.9%.
19. The method in accordance with 11 wherein the content of chlorine in particulates is from 0.01wt. % to wt. 85%.
20. The method in accordance with 11 wherein the mass proportion of particulates to the mass of proppant is from 0.1wt. % to wt. 99.9%.
21. The method in accordance with 1 wherein the particulate size varies from 0.1 microns to 10 mm.
22. The method in accordance with 1 wherein the content of polyvinylchloride and polyvinyldenchloride in copolymers is from 0.1 wt. % to wt. 99.9%.
23. The method in accordance with 1 wherein the content of chlorine in particulates is from 0.01 wt. % to wt. 85%.
24. The method in accordance with 1 wherein the mass proportion of particulates to the mass of proppant is from 0.1 wt. % to wt. 99.9%.
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RU2007105188 | 2007-02-13 | ||
RU2007105188/03A RU2347069C2 (en) | 2007-02-13 | 2007-02-13 | Created fracture cleaning process |
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US20080190610A1 true US20080190610A1 (en) | 2008-08-14 |
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US12/029,995 Abandoned US20080190610A1 (en) | 2007-02-13 | 2008-02-12 | Fracture Clean up Method |
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US (1) | US20080190610A1 (en) |
CA (1) | CA2620788A1 (en) |
RU (1) | RU2347069C2 (en) |
Cited By (10)
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EP2804923A1 (en) * | 2012-01-17 | 2014-11-26 | Saudi Arabian Oil Company | Non-acidic-exothermic sandstone stimulation fluids |
WO2016011310A1 (en) * | 2014-07-17 | 2016-01-21 | Aramco Services Company | Encapsulation and controlled delivery of strong mineral acids |
US9488042B2 (en) | 2014-04-17 | 2016-11-08 | Saudi Arabian Oil Company | Chemically-induced pulsed fracturing method |
US9701894B2 (en) | 2014-04-17 | 2017-07-11 | Saudi Arabian Oil Company | Method for enhanced fracture cleanup using redox treatment |
US9738824B2 (en) | 2011-11-23 | 2017-08-22 | Saudi Arabian Oil Company | Tight gas stimulation by in-situ nitrogen generation |
US9803133B2 (en) | 2012-05-29 | 2017-10-31 | Saudi Arabian Oil Company | Enhanced oil recovery by in-situ steam generation |
US10053614B2 (en) | 2014-04-17 | 2018-08-21 | Saudi Arabian Oil Company | Compositions for enhanced fracture cleanup using redox treatment |
US10308862B2 (en) | 2014-04-17 | 2019-06-04 | Saudi Arabian Oil Company | Compositions and methods for enhanced fracture cleanup using redox treatment |
US11414972B2 (en) | 2015-11-05 | 2022-08-16 | Saudi Arabian Oil Company | Methods and apparatus for spatially-oriented chemically-induced pulsed fracturing in reservoirs |
US11739616B1 (en) | 2022-06-02 | 2023-08-29 | Saudi Arabian Oil Company | Forming perforation tunnels in a subterranean formation |
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RU2507389C1 (en) * | 2012-08-07 | 2014-02-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Кубанский государственный технологический университет" (ФГБОУ ВПО "КубГТУ") | Method of formation hydraulic fracturing |
US12007368B2 (en) * | 2019-09-24 | 2024-06-11 | Halliburton Energy Services, Inc. | Fragile and normal viscoelastic components of drilling fluid gels |
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US10053614B2 (en) | 2014-04-17 | 2018-08-21 | Saudi Arabian Oil Company | Compositions for enhanced fracture cleanup using redox treatment |
US10442977B2 (en) | 2014-04-17 | 2019-10-15 | Saudi Arabian Oil Company | Compositions and methods for enhanced fracture cleanup using redox treatment |
US10450499B2 (en) | 2014-04-17 | 2019-10-22 | Saudi Arabian Oil Company | Compositions and methods for enhanced fracture cleanup using redox treatment |
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US9488042B2 (en) | 2014-04-17 | 2016-11-08 | Saudi Arabian Oil Company | Chemically-induced pulsed fracturing method |
US10442978B2 (en) | 2014-04-17 | 2019-10-15 | Saudi Arabian Oil Company | Compositions and methods for enhanced fracture cleanup using redox treatment |
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US10501687B2 (en) | 2014-07-17 | 2019-12-10 | Aramco Services Company | Encapsulation and controlled delivery of strong mineral acids |
US11041117B2 (en) | 2014-07-17 | 2021-06-22 | Aramco Services Company | Encapsulation and controlled delivery of strong mineral acids |
US11041116B2 (en) | 2014-07-17 | 2021-06-22 | Aramco Services Company | Encapsulation and controlled delivery of strong mineral acids |
US11414972B2 (en) | 2015-11-05 | 2022-08-16 | Saudi Arabian Oil Company | Methods and apparatus for spatially-oriented chemically-induced pulsed fracturing in reservoirs |
US11739616B1 (en) | 2022-06-02 | 2023-08-29 | Saudi Arabian Oil Company | Forming perforation tunnels in a subterranean formation |
Also Published As
Publication number | Publication date |
---|---|
CA2620788A1 (en) | 2008-08-13 |
RU2347069C2 (en) | 2009-02-20 |
RU2007105188A (en) | 2008-09-10 |
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