CN115109576B - Fracturing fluid system and fracturing method - Google Patents
Fracturing fluid system and fracturing method Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 45
- ZRALSGWEFCBTJO-UHFFFAOYSA-N Guanidine Chemical compound NC(N)=N ZRALSGWEFCBTJO-UHFFFAOYSA-N 0.000 claims abstract description 74
- 238000004132 cross linking Methods 0.000 claims abstract description 44
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 40
- CHJJGSNFBQVOTG-UHFFFAOYSA-N N-methyl-guanidine Natural products CNC(N)=N CHJJGSNFBQVOTG-UHFFFAOYSA-N 0.000 claims abstract description 37
- SWSQBOPZIKWTGO-UHFFFAOYSA-N dimethylaminoamidine Natural products CN(C)C(N)=N SWSQBOPZIKWTGO-UHFFFAOYSA-N 0.000 claims abstract description 37
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- 239000003513 alkali Substances 0.000 claims description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 2
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- ZIXQIYLQPUHVBI-UHFFFAOYSA-N 2-[carbamimidoyl(3-hydroxypropyl)amino]acetic acid Chemical compound C(=O)(O)CN(C(=N)N)CCCO ZIXQIYLQPUHVBI-UHFFFAOYSA-N 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
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- KFSLWBXXFJQRDL-UHFFFAOYSA-N Peracetic acid Chemical compound CC(=O)OO KFSLWBXXFJQRDL-UHFFFAOYSA-N 0.000 description 4
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- 229910052742 iron Inorganic materials 0.000 description 4
- 239000002736 nonionic surfactant Substances 0.000 description 4
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- 230000014759 maintenance of location Effects 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 2
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- 230000006698 induction Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 150000002506 iron compounds Chemical class 0.000 description 1
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 description 1
- 235000015110 jellies Nutrition 0.000 description 1
- 239000008274 jelly Substances 0.000 description 1
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- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- 241001148471 unidentified anaerobic bacterium Species 0.000 description 1
Classifications
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- 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
- C09K8/66—Compositions based on water or polar solvents
- C09K8/68—Compositions based on water or polar solvents containing organic compounds
- C09K8/685—Compositions based on water or polar solvents containing organic compounds containing cross-linking agents
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- 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
- C09K8/605—Compositions for stimulating production by acting on the underground formation containing biocides
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- 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
- C09K8/84—Compositions based on water or polar solvents
- C09K8/86—Compositions based on water or polar solvents containing organic compounds
- C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/887—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
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- 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
- C09K8/84—Compositions based on water or polar solvents
- C09K8/86—Compositions based on water or polar solvents containing organic compounds
- C09K8/88—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/90—Compositions based on water or polar solvents containing organic compounds macromolecular compounds of natural origin, e.g. polysaccharides, cellulose
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- 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
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- C—CHEMISTRY; METALLURGY
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- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K2208/00—Aspects relating to compositions of drilling or well treatment fluids
- C09K2208/24—Bacteria or enzyme containing gel breakers
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- 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
- C09K2208/26—Gel breakers other than bacteria or enzymes
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- Physics & Mathematics (AREA)
- Geochemistry & Mineralogy (AREA)
- Colloid Chemistry (AREA)
Abstract
The invention provides a fracturing fluid system and a fracturing method. The fracturing fluid system comprises a fracturing fluid base fluid, a crosslinking component and a gel breaker; wherein the mass of the crosslinking component is 0.8-1.2% of the mass of the fracturing fluid base fluid; the mass of the gel breaker is 0.04-0.2% of the mass of the base fluid of the fracturing fluid; the base liquid of the fracturing fluid comprises, by mass, 0.25-0.4% of guanidine gum, 5-8% of a waterproof locking agent, 1-2% of a cleanup additive, 0.2-1% of a pH regulator and the balance of water. According to the fracturing fluid system, the components are effectively matched, so that the fracturing fluid system has a good fracturing effect, and the fracturing fluid system has low damage to a reservoir. The fracturing method disclosed by the invention uses a fracturing fluid system with good fracturing effect and low damage to a reservoir, so that effective fracturing can be realized, the oil gas production efficiency is improved, and the stable and efficient oil gas production is ensured.
Description
Technical Field
The invention relates to a fracturing fluid system and a fracturing method, and belongs to the technical field of oil and gas reservoir development.
Background
Along with the continuous improvement of petroleum exploration and development technology, the development proportion of fracture-type compact sandstone hydrocarbon reservoirs is increased year by year, and the fracture-type compact sandstone hydrocarbon reservoirs generally have the characteristics of deep burial, small porosity, low matrix permeability, different fracture development degrees, strong heterogeneity and the like, and the hydrocarbon channels in the stratum are required to be improved through a fracturing transformation technology, so that the seepage capability of hydrocarbon is increased, and the efficient exploitation of hydrocarbon is realized.
In the fracturing reconstruction construction, a fracturing fluid system is often adopted in order to meet the construction requirements of deep wells and ultra-deep wells. However, fracturing fluid systems tend to damage reservoirs, thereby affecting the fracturing modification effect and causing lost production in oil and gas wells when severe. Damage to a fractured reservoir by a fracturing fluid system can be mainly divided into damage to a matrix by filtrate of the fracturing fluid system and damage to a dual medium of a fracture and the matrix by gel breaking liquid of the fracturing fluid system. The damage of the fracturing fluid filtrate to the matrix is mainly characterized by liquid phase damage which occurs easily when the fracturing fluid filtrate invades the matrix, for example, the fracturing fluid filtrate is hydrated and swelled when meeting water sensitivity clay mineral induction, so that the permeability of the reservoir is reduced; for another example, fracturing fluid system filtrate enters the throat and water lock damage due to capillary resistance results in reduced reservoir permeability and relative oil and gas permeability. The damage of the fracturing fluid system gel breaking liquid to the dual medium of the crack and the matrix is mainly shown in that on one hand, the fracturing fluid system gel breaking liquid can form a residue filter cake on the wall surface of the crack, thereby reducing the effective width of the crack and reducing the flow conductivity of the crack; on the other hand, the residues of the fracturing fluid system remain on the wall surface of the fracture to form a filter cake skeleton, so that pore throats are blocked, and the permeability of the reservoir is reduced.
How to provide a fracturing fluid system and reduce the damage of the fracturing fluid system to a reservoir is a technical problem to be solved in the technical field of oil and gas reservoir development.
Disclosure of Invention
The invention provides a fracturing fluid system, which reduces damage to a reservoir by the fracturing fluid system through the design of components in the fracturing fluid system.
The invention also provides a fracturing method for carrying out fracturing construction by using the fracturing fluid system, which has good fracturing effect on the reservoir and small damage to the reservoir.
The first aspect of the invention provides a fracturing fluid system, wherein the fracturing fluid system comprises a fracturing fluid base fluid, a crosslinking component and a gel breaker;
wherein the mass of the crosslinking component is 0.8-1.2% of the mass of the fracturing fluid base fluid;
the mass of the gel breaker is 0.04-0.2% of the mass of the fracturing fluid base fluid;
the fracturing fluid base fluid comprises, by mass, 0.25-0.4% of guanidine gum, 5-8% of waterproof locking agent, 1-2% of cleanup additive, 0.2-1% of pH regulator and the balance of water.
The fracturing fluid system as described above, wherein the crosslinking component comprises a crosslinking agent and a pH adjuster, and the mass ratio of the crosslinking agent to the pH adjuster is 1:1-1.5.
The fracturing fluid system as described above, wherein the guanidine gum is hydroxypropyl guanidine gum and/or carboxymethyl hydroxypropyl guanidine gum.
The fracturing fluid system comprises a water-proof locking agent, wherein the water-proof locking agent is at least one of methanol, a nonionic surfactant and a fluorocarbon surfactant.
A fracturing fluid system as described above, wherein the surface tension of the cleanup agent is no higher than 25mN/m and the interfacial tension is no higher than 2mN/m.
The fracturing fluid system, wherein the gel breaker is at least one of ammonium persulfate, potassium persulfate, biological enzymes and peracetic acid.
The fracturing fluid system comprises, by mass, 0.025-0.06% of citric acid.
The fracturing fluid system comprises the following components in percentage by mass: 1 to 1.5 percent of demulsifier, 2 to 25 percent of weighting agent, 0.3 to 0.5 percent of temperature stabilizer and 0 to 0.1 percent of bactericide.
The invention also provides a fracturing method using the fracturing fluid system, which comprises the following steps of:
mixing the fracturing fluid base fluid with a crosslinking component to obtain a gel system;
mixing the gel system with a gel breaker to obtain the fracturing fluid system;
the fracturing fluid system is added to the wellbore.
The third aspect of the present invention also provides another fracturing method using the fracturing fluid system, comprising the following steps:
mixing the fracturing fluid base fluid with a crosslinking component to obtain a gel system;
adding the gel system into a well bore;
the breaker is added to the wellbore.
According to the fracturing fluid system, on one hand, the fracturing fluid system is a water-based fracturing fluid system with guanidine gum as a thickening agent, the content of guanidine gum is low, the addition amount of a gel breaker is small, the content of residues after gel breaking is low, the residues can be effectively prevented from blocking throat holes of a reservoir, the permeability of the reservoir is prevented from being reduced, and therefore the damage of the fracturing fluid system to the reservoir is reduced.
On the other hand, the addition of the cleanup additive and the coordination of the components enable the flow back rate of the fracturing fluid system to be high, the fracturing fluid system used for carrying out fracturing construction can effectively flow back from the reservoir, the amount of the fracturing fluid system filtrate remained in the reservoir after the fracturing construction is completed is reduced, the liquid phase damage of the fracturing fluid system filtrate and the reservoir matrix is inhibited, the permeability of the reservoir is prevented from being reduced, and the damage of the fracturing fluid system to the reservoir is reduced.
In addition, the waterproof locking agent can be matched with each component, so that the surface tension of a fracturing fluid system after gel breaking is reduced, and the water locking damage caused by liquid phase retention after filtrate of the fracturing fluid system invades a reservoir is obviously reduced, so that the flowback efficiency of the fracturing fluid system can be improved, the damage of the fracturing fluid system to the reservoir is reduced, the flowback pressure during fracturing construction can be reduced due to the reduction of the water locking damage, and the energy consumption of fracturing construction is effectively reduced.
It is worth mentioning that the fracturing fluid system provided by the invention has the advantages that through the compound effect among the components, the damage to a reservoir is small, the good sand carrying capacity and the good temperature resistance are realized, the wellhead pressure can be obviously reduced when the fracturing fluid system is used in fracturing construction, the oil gas production efficiency is improved, the stable oil gas production is maintained, and the fracturing fluid system has wide practicability.
The fracturing method disclosed by the invention uses a fracturing fluid system with good fracturing effect and small damage to a reservoir, so that the fracturing method disclosed by the invention can provide good fracturing pressure, improve the oil gas production efficiency, ensure stable oil gas production, is simple and convenient to operate, and has a great application prospect in the technical field of oil gas reservoir development.
Drawings
FIG. 1 is a flow chart of a fracturing method according to an embodiment of the present invention;
FIG. 2 is a flow chart of a fracturing method according to another embodiment of the present invention;
FIG. 3 is a graph showing the results of the viscosity test of the base fluid of the fracturing fluid obtained in examples 1-3 of the present invention;
FIG. 4 is a graph showing the results of the viscosity test of the base fluid of the fracturing fluid obtained in examples 4-5 of the present invention;
FIG. 5 is a construction graph of an embodiment of a fracturing method of the present invention;
FIG. 6 is a plot of a production test scenario of an embodiment of a fracturing method of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
A first aspect of the present invention provides a fracturing fluid system comprising a fracturing fluid base fluid, a crosslinking component, and a breaker;
wherein the mass of the crosslinking component is 0.8-1.2% of the mass of the fracturing fluid base fluid;
the mass of the gel breaker is 0.04-0.2% of the mass of the base fluid of the fracturing fluid;
the base liquid of the fracturing fluid comprises, by mass, 0.25-0.4% of guanidine gum, 5-8% of a waterproof locking agent, 1-2% of a cleanup additive, 0.2-1% of a pH regulator and the balance of water.
The raw materials used in the fracturing fluid system of the invention are all chemical materials which are commercially available and are commonly used in the art.
The various constituents of the fracturing fluid system of the present invention will be described in detail below.
The guanidine gum is a commonly used thickening agent of a fracturing fluid system, and is mainly used for improving the viscosity of the fracturing fluid system.
The crosslinking component in the invention is a main additive of a fracturing fluid system, and can form high-viscosity gel (jelly) with guanidine gum, so that the fracturing fluid system has excellent joint making and sand carrying capacity when being used for fracturing construction.
The present invention does not impose a strict limitation on the guanidine gum and the crosslinking component, as long as the guanidine gum can form a gel with the crosslinking component. In the specific implementation process, the guanidine gum can be selected from but not limited to modified super guanidine gum JK101 of Kunshan of China petrochemical industry, and the crosslinking component can be selected from but not limited to ZYT-A of Kurler New Kate oilfield chemical technology Co. In the specific implementation process, the guanidine gum with lower concentration is selected on the basis of meeting the fracturing effect of the fracturing fluid system, so that the damage to a reservoir is further reduced.
The waterproof locking agent is an additive in a fracturing fluid system, and the damage of the fracturing fluid system to reservoir water locking can be reduced. The waterproof locking agent is mainly used for increasing the contact angle between a liquid phase in the fracturing fluid system and a solid phase of a reservoir, so that the interfacial tension of filtrate after gel breaking of the fracturing fluid system can be reduced, the flowback efficiency can be accelerated, and the damage of the fracturing fluid system to the reservoir can be reduced.
The present invention is not restricted strictly to the waterproof locking agent, and for example, the waterproof locking agent may be a surfactant or a lower alcohol.
The cleanup additive can improve the flowback efficiency of the fracturing fluid system, and is beneficial to increasing the quantity of the fracturing fluid system gel breaking liquid returned to the ground from the reservoir after the fracturing transformation is completed, so that the damage of the fracturing fluid system to the reservoir is reduced.
The invention does not limit the cleanup additive strictly, so long as the invention is beneficial to improving the flowback efficiency of the fracturing fluid system. In the course of the specific implementation process, the method comprises, the cleanup additive can be at least one of fluorocarbon DJ-02 used for the fracture acidification of the Korla Xinkelet oilfield chemical company, organosilicon surfactant ZP used for the fracture acidification of the Korla Yi Gong trade company, fluorocarbon XH-P used for the acidification (fracture) of the shou Xinhai chemical company, fluorocarbon VT-2 used for the acidification (fracture) of the Fangzhu Tianyang petroleum technology company, and perfluoroalkyl nonionic surfactant TZC-01 used for the fracture acidification of the Xinjiang and He Chemicals company. The present invention may be selected from, but not limited to, the above-described drainage aids.
According to the invention, the pH of the fracturing fluid system can be regulated according to the reaction requirement of the guanidine gum and the crosslinking component by using 0.2-1% of the pH regulator, so that the gelling performance of the crosslinking component and the guanidine gum in the base fluid of the fracturing fluid is improved.
The invention does not limit the pH regulator strictly, and in the specific implementation process, the pH regulator can select organic alkali ZYT-B of Korla new Kate oilfield chemical technology Co.
The invention does not limit the water in the base liquid of the fracturing fluid strictly, and can be selected according to the production conditions in the specific implementation process. For example, in the actual fracturing construction process, the demand for the fracturing fluid system is large, and tap water can be selected to reduce the fracturing construction cost. Of course, deionized water can be selectively used to avoid introducing impurities into the fracturing fluid system, further improve the fracturing construction effect and reduce the damage of the fracturing fluid system to the reservoir.
In the process of fracturing construction, in order to realize effective flowback of a fracturing fluid system, a gel breaker is needed to be used in the fracturing fluid system so as to break gel formed by guanidine gum and a crosslinking component after the fracturing construction and promote smooth flowback of the fracturing fluid system. The breaker may be selected from, but is not limited to, FRC-90B from the Beijing family of Maishi oilfield Chemicals, inc.
In the specific implementation process, the content of each component in the fracturing fluid system can be adjusted in the range according to different fracturing requirements of the oil and gas well, so that the fracturing fluid system can be more suitable for the oil and gas well. For example, in some implementations, the fracturing fluid system may require the addition of a weighting agent that is detrimental to the breaking of the fracturing fluid system, and thus the amount of breaker may be increased to ensure good breaking of the fracturing fluid system.
The fracturing fluid system disclosed by the invention uses the guanidine gum as the thickener of the fracturing fluid base fluid, the content of the guanidine gum in the fracturing fluid base fluid is 0.25-0.4%, the addition of the gel breaker is 0.04-0.2% of that of the fracturing fluid base fluid, and under the conditions of lower guanidine gum concentration and gel breaker addition, the good fracturing effect of the fracturing fluid base fluid and lower residue rate after gel breaking are realized, the phenomenon that the residue of the fracturing fluid system blocks the throat hole of a reservoir can be effectively avoided, the permeability of the reservoir is prevented from being reduced, and the damage of the fracturing fluid system to the reservoir is reduced. Moreover, the guanidine gum is used as an environment-friendly thickener, so that the pollution of a fracturing fluid system to a reservoir can be further reduced.
In addition, the flowback efficiency of the fracturing fluid system is improved through the coordination of 1-2% of the cleanup additive and each component of the fracturing fluid base fluid, the fracturing fluid system used for carrying out fracturing construction can be effectively flowback from the reservoir, the amount of the fracturing fluid system filtrate remained in the reservoir after the completion of the fracturing construction is reduced, the liquid phase damage of the fracturing fluid system filtrate and the reservoir matrix is inhibited, the permeability of the reservoir is prevented from being reduced, and the damage of the fracturing fluid system to the reservoir is reduced.
In addition, the waterproof locking agent disclosed by the invention can be matched with all components, so that the surface tension of a fracturing fluid system after gel breaking is reduced, and the water locking damage caused by liquid phase retention after filtrate of the fracturing fluid system invades a reservoir is obviously reduced, thereby reducing the flowback pressure, effectively reducing the energy consumption of fracturing construction, improving the flowback efficiency of the fracturing fluid system and reducing the damage of the fracturing fluid system to the reservoir.
It is worth mentioning that the fracturing fluid system provided by the invention has small damage to a reservoir, good sand carrying capacity and good temperature resistance through the compound action among the components, can obviously reduce wellhead pressure during fracturing construction, maintain stable oil gas production, improve oil gas production efficiency, and has wide practicability.
In order to further improve the gelling properties of the crosslinking component and the guanidine gum, in some embodiments of the invention, the crosslinking component comprises a crosslinking agent and a pH adjuster, the mass ratio of the crosslinking agent to the pH adjuster being 1:1-1.5.
The pH of the cross-linking liquid system can be further adjusted by containing the pH regulator in the cross-linking component, so that the pH of the cross-linking liquid system is more suitable for forming cross-linking between the cross-linking component and the guanidine gum, and the gel formed between the cross-linking component and the guanidine gum is more uniform.
The pH regulator is contained in the crosslinking component so that the pH of the fracturing fluid system is more favorable for the gel formation of the crosslinking component and the guanidine gum, and a large amount of gel can be effectively prevented from being formed before the crosslinking component is fully mixed with the fracturing fluid base fluid, so that the gel formation of the fracturing fluid system is uneven and the gel formation effect is poor.
In some embodiments of the invention, the guanidine gum is hydroxypropyl guanidine gum and/or carboxymethyl hydroxypropyl guanidine gum.
The hydroxypropyl guanidine gum and/or carboxymethyl hydroxypropyl guanidine gum can further improve the affinity of the guanidine gum and water, reduce the content of insoluble substances in the fracturing fluid system and the content of residues after the fracturing fluid system breaks gel, and further reduce the damage of the fracturing fluid system to a reservoir.
The inventor finds that under the condition that the rest components are the same, carboxymethyl hydroxypropyl guanidine gum and hydroxypropyl guanidine gum with the same concentration are used for preparing a fracturing fluid system, and after the fracturing fluid system is tested according to a testing method specified by SY/T5107-2005 standard, the residue content of the fracturing fluid system prepared by carboxymethyl hydroxypropyl guanidine gum is 1/3 of that of the hydroxypropyl guanidine gum fracturing fluid after gum breaking; after the displacement test is carried out on the fracturing fluid system with the injection amount of the gel breaking liquid of 5PV, the damage of the fracturing fluid system prepared by the carboxymethyl hydroxypropyl guar to the reservoir fracture is 45% lower than that of the hydroxypropyl guar fracturing fluid.
In other embodiments of the invention, the guanidine gum is carboxymethyl hydroxypropyl guanidine gum.
It should be noted that while carboxymethyl hydroxypropyl guanidine gum is less damaging to the reservoir than hydroxypropyl guanidine gum, the price of carboxymethyl hydroxypropyl guanidine gum is higher than hydroxypropyl guanidine gum and the cost of preparing the fracturing fluid system is higher. Therefore, in specific implementation, a person skilled in the art can select a proper guanidine gum type by integrating damage to a reservoir caused by the fracturing fluid system and preparation cost of the fracturing fluid system.
The inventor finds that when the waterproof locking agent is at least one of methanol, nonionic surfactant and fluorocarbon surfactant in the research process, the flowback efficiency of the fracturing fluid system can be further improved, and the damage to the reservoir can be further reduced.
When the waterproof locking agent is methanol, the waterproof locking agent not only can reduce the interfacial tension between the fracturing fluid system and the reservoir, and improve the flowback efficiency of the fracturing fluid system, but also can bring out fracturing fluid filtrate remained in the reservoir when the methanol is easy to dissolve with water and volatilize, so that the water locking damage of the fracturing fluid system to the reservoir can be effectively reduced, the flowback efficiency of the fracturing fluid system is further improved, and the damage of the fracturing fluid system to the reservoir is reduced. Moreover, the cost of the methanol is low, which is beneficial to reducing the cost of fracturing construction.
In some embodiments of the invention, the surface tension of the cleanup is no higher than 25mN/m and the interfacial tension is no higher than 2mN/m.
In the invention, the surface tension of the cleanup additive is obtained by adopting a test mode defined by SY/T5755-2016 standard; in the invention, the interfacial tension of the cleanup additive is obtained by testing in a test mode defined by SY/T5755-2016 standard.
The inventor finds that when the surface tension and the interfacial tension of the cleanup additive are in the above ranges, the cleanup additive can more effectively coordinate with the rest components of the fracturing fluid system, so that the flowback efficiency of the fracturing fluid system is improved, and the damage of the fracturing fluid system to a reservoir is smaller.
The breaker of the fracturing fluid system is one of the important components affecting the performance of the fracturing fluid system. In some embodiments of the invention, the breaker is at least one of ammonium persulfate, potassium persulfate, biological enzymes, peracetic acid.
The structure of the breaker is not strictly limited, for example, the breaker can be powder of the breaker, or capsule type breaker can be prepared by wrapping the breaker powder by using a capsule shell. Compared with the gel breaker powder directly used, the gel breaker with the capsule structure basically does not release the gel breaker at normal temperature and normal pressure, but after the fracturing construction is finished, the capsule shell is broken and deformed due to extrusion, heating, corrosion and other reasons, so that the internal gel breaker powder is slowly released.
It can be understood that during the fracturing construction, the fracturing fluid system needs to have certain viscosity, so that the fracturing fluid system has certain sand carrying and seam making capabilities during the fracturing construction, the fracturing construction effect is improved, and after the fracturing construction is finished, the fracturing fluid system needs to be thoroughly broken under the action of a breaker, so that effective flowback is realized. In the fracturing fluid system, the gel breaker in a capsule form can be added into a shaft together with the rest components of the fracturing fluid system during fracturing construction, so that the steps of fracturing construction are simplified, the efficiency of fracturing construction is improved, and the gel breaker can realize effective gel breaking of the fracturing fluid system after the fracturing construction is finished, so that the fracturing fluid system is promoted to effectively flow back.
In order to further improve the fracturing construction effect, in some embodiments of the invention, the fracturing fluid base fluid further comprises 0.025-0.06% of citric acid by mass percent.
In the fracturing construction process, the fracturing fluid system is easy to erode iron compounds on the walls of the reservoir and the shaft in the pumping process, the iron ion content in the fracturing fluid system is increased, and iron ions generate ferric hydroxide precipitation when the pH value is large, so that the reservoir and the shaft are blocked, and the fracturing construction effect is reduced. And 0.025-0.06% of citric acid is added into the fracturing fluid system, so that the complex can be formed between the citric acid and the iron ions on the basis that the pH value of the fracturing fluid base fluid meets the requirement of good gel forming property of guanidine gum and crosslinking components, and the iron ions are prevented from sedimentation to form precipitation, thereby reducing the damage of the fracturing fluid system to a reservoir and improving the fracturing construction effect.
In the specific implementation process, components with specific effects can be specifically included in the fracturing fluid base fluid on the basis of the fracturing fluid system aiming at different types of oil and gas reservoirs, so that damage of the fracturing fluid system to a reservoir is further reduced, and the fracturing construction effect is improved.
In some embodiments of the present invention, the fracturing fluid base fluid further comprises, in mass percent: 1 to 1.5 percent of demulsifier, 2 to 25 percent of weighting agent, 0.3 to 0.5 percent of temperature stabilizer and 0 to 0.1 percent of bactericide.
Aiming at a condensate gas reservoir, condensate oil in a stratum is easy to generate emulsification with a fracturing liquid system to block pore throats and cracks of the stratum, so that the demulsifier is added to help promote smooth flowback of a fracturing liquid system gel breaking liquid after the fracturing construction is completed, improve flowback efficiency of the fracturing liquid system gel breaking liquid, and further reduce damage of the fracturing liquid system to a reservoir.
The demulsifier is not strictly limited, and can be, for example, demulsifier epoxypropane DJ-10 for fracture acidification of Korla New Kate oilfield chemical technology Co., ltd, emulsion breaker modified polyether GTA-7 for fracture acidification of Gulaite technology Co., ltd, and demulsifier nonionic surfactant ZX-11 for fracture of Star energy technology Co., beijing century.
In the process of fracturing construction of the ultra-deep high-pressure well, the weighting agent can be included in the fracturing fluid base fluid, and the density of the fracturing fluid system can be effectively increased, so that the reservoir pressure can be increased by means of the vertical pressure of the fracturing fluid system, the pressure of fracturing construction of a well head can be effectively reduced while good fracturing construction effect is ensured, and the safety risk of fracturing construction is reduced.
The present invention is not limited to the weighting agent, and the inventors found that potassium chloride can be used as the weighting agent during the course of the study. The potassium chloride is used as the weighting agent of the fracturing fluid system, so that the density of the fracturing fluid system can be remarkably increased, the safety risk of fracturing construction is reduced, and the K in the potassium chloride is more notable + Can play a role in inhibiting the expansion of clay minerals in the stratum, and further reduce the damage of a fracturing fluid system to a reservoir. The specific amount of weighting agent used in a particular fracturing construction may be determined based on reservoir pressure and the limit pump pressure that the wellhead can withstand. The addition of the weighting agent has a large influence on the gel breaking effect of the fracturing fluid system, and in some embodiments of the invention, when the mass content of the weighting agent in the fracturing fluid base fluid is 20%, the dosage of the gel breaking agent is 0.15-0.2% of the mass of the fracturing fluid base fluid, at the moment, the gel breaking effect of the fracturing fluid system is good, the flowback rate efficiency of the fracturing fluid system is high, and the damage to a reservoir is small.
The temperature stabilizer is beneficial to improving the rheological property of the fracturing fluid system at high temperature, and can improve the joint making and sand carrying effects of the fracturing fluid system at high temperature when the fracturing fluid system is used for fracturing a high-temperature reservoir, so that the fracturing construction effect of a high-temperature oil-gas well is improved.
The invention does not limit the temperature stabilizer strictly, and in the specific implementation process, the temperature stabilizer sulfite DJ-14 for fracturing of Korla new Kate oilfield chemical technology Co.
The bactericide is added into the fracturing fluid system, so that the decomposition of guanidine gum by anaerobic bacteria in a reservoir can be prevented, the stability of the fracturing fluid system is maintained, and the fracturing construction effect is improved.
The present invention is not restricted to the bactericide, and for example, the bactericide may be formaldehyde.
The second aspect of the invention provides a fracturing method using the fracturing fluid system, which comprises the following steps:
s101: mixing the fracturing fluid base fluid with the crosslinking component to obtain a gel system;
s102: mixing the gel system with a gel breaker to obtain a fracturing fluid system;
s103: a fracturing fluid system is added to the wellbore.
Fig. 1 is a flow chart of a fracturing method according to an embodiment of the invention. According to the fracturing method, the fracturing fluid system has good sand carrying capacity, good seam making capacity and high fracturing pressure, so that the fracturing construction is efficient and reliable, and the oil gas production efficiency can be improved; the fracturing fluid system used in the fracturing method has little damage to the reservoir, thereby being beneficial to maintaining stable and controllable oil gas production.
In addition, the fracturing method can add each component of the fracturing fluid system into the shaft after the components are mixed on the well, so that the fracturing construction operation is simpler, the fracturing construction efficiency is improved, the influence of the fracturing construction on the oil gas production period is reduced, the components in the fracturing fluid system can be more uniformly mixed, the gel forming effect of the guanidine gum and the crosslinking component and the gel breaking effect of the gel breaker can be improved, the fracturing construction effect is more obvious, and the fracturing construction effect on a reservoir is less.
The third aspect of the present invention provides another fracturing method using the fracturing fluid system, comprising the steps of:
s104: mixing the fracturing fluid base fluid with the crosslinking component to obtain a gel system;
s105: adding a gel system into a well bore;
s106: a breaker is added to the wellbore.
Fig. 2 is a flow chart of a fracturing method according to another embodiment of the invention. The fracturing method of the present invention may also employ a fracturing fluid system according to the steps shown in S104-S106 above.
In a specific implementation process, how to use the fracturing fluid system provided by the invention can be determined according to the structural characteristics of the breaker. For example, when the breaker is a capsule breaker, the fracturing construction may be performed by a method including S101 to S103 due to the characteristic that the capsule breaker releases a large amount of internal breaker powder after the construction is completed. When the breaker is breaker powder directly, the method comprising S104-S106 can be adopted for carrying out fracturing construction, and the breaker is added into a shaft after the fracturing construction is completed so as to prevent the breaker from damaging sand carrying and seam making capacity of a fracturing fluid system.
The fracturing fluid system and the fracturing method of the present invention are described in detail below by way of specific examples.
In the following examples and comparative examples, modified super guanidine gum JK101 of chinese petrochemistry kunshan company was used as guanidine gum; potassium chloride and citric acid are all of industrial purity; the cleanup additive adopts fluorocarbon DJ-02 which is a cleanup additive for fracture acidizing of the Korla new Kate oilfield chemical technology Co., ltd; the demulsifier adopts demulsifier epoxypropane DJ-10 for fracture acidizing of Korla new Kate oilfield chemical technology Co-Ltd; the temperature stabilizer adopts a temperature stabilizer sulfite DJ-14 for fracturing of the Korla new Kate oilfield chemical technology Co., ltd; the bactericide adopts formaldehyde with industrial grade purity; the waterproof locking agent adopts industrial-grade pure methanol; the pH value regulator adopts organic alkali ZYT-B as a crosslinking regulator for fracturing of the Korla new Kate oilfield chemical technology Co-efficient; the cross-linking agent adopts organic boron ZYT-A as a cross-linking agent for fracturing of Korla New Kate oilfield chemical technology Co., ltd; the breaker adopts capsule breaker ammonium persulfate FRC-90B for fracturing of Beijing family Maishi oilfield chemical technology Co.
Example 1
The fracturing fluid system in this embodiment is obtained by the steps of:
1. guanidine gum, weighting agent, citric acid, cleanup additive, demulsifier, temperature stabilizer, bactericide, waterproof locking agent, pH regulator and water are mixed according to the mass percentage of 0.4 percent: 2%:0.025%:1%:1%:0.5%:0.1%:5%:0.2%:89.775% to obtain a fracturing fluid base fluid;
2. the cross-linking agent and the pH regulator are mixed according to the mass ratio of 1:1 mixing to obtain a crosslinking component;
3. and (2) mixing the fracturing fluid base fluid obtained in the step (1) with the crosslinking component obtained in the step (2) according to a mass ratio of 100:0.8, mixing to obtain a gel system;
4. mixing the gel system obtained in the step 3 with a gel breaker, wherein the mass of the gel breaker is 0.04% of the mass of the base fluid of the fracturing fluid;
examples 2 to 5
The fracturing fluid systems of examples 2-5 were prepared in essentially the same manner as in example 1, except that: the mass content of the weighting agent in the fracturing fluid base fluid and/or the mass content of the fracturing fluid system breaker based on the fracturing fluid base fluid are specifically referred to in table 1.
Comparative examples 1 to 2
The preparation process of the fracturing fluid system in comparative examples 1-2 was essentially the same as in example 1, except that: the breaker is based on the mass content of the fracturing fluid base fluid, see in particular table 1.
TABLE 1
Test examples
The fracturing fluid systems obtained in examples 1 to 5 and comparative examples 1 to 2 were tested for gel breaking time, gel breaking fluid viscosity and residue content at normal temperature (23.+ -. 2 ℃) according to the test methods specified in SY/T5107-2005 and SY/T6376-2008, and the relevant results are shown in Table 2;
the damage of the fracturing fluid system obtained in the examples 1-3 to the core matrix is tested after the fracturing fluid base fluid is mixed with the gel breaker for 2 hours at 90 ℃ according to the test method specified in SY/T5107-2005; after breaking the gel at 90 ℃ for 2 hours according to the test method specified by SY/T5107-2005, the fracturing fluid systems obtained in examples 4-5 and comparative examples 1-2 were tested for damage to core cracks, and the results are shown in Table 3;
the viscosity of the fracturing fluid base fluid obtained in examples 1-3 was tested according to the test method specified in SY/T5107-2005, the results are shown in FIG. 3; the fracturing fluid base fluids obtained in examples 4-5 were tested for viscosity and the results are shown in figure 4.
As can be seen from fig. 3 and 4:
in examples 1 to 3, the weight content of the weighting agent was 2%, and as shown in FIG. 3, the initial viscosity of the base fluid of the fracturing fluid after crosslinking could reach 678 mPas, and the viscosity decreased with increasing temperature to 110 ℃, but still was above 250 mPas, at 130 ℃ for 170s -1 Shearing for 120min, and keeping the viscosity of the base fracturing fluid above 200 mPas all the time, so that the rheological property is good, and the examples 1-3 are shownThe fracturing fluid base fluid has good fracturing capacity and good temperature resistance;
in examples 4 to 5, the weight content of the weighting agent was 20%, and as shown in FIG. 4, the initial viscosity of the base fluid of the fracturing fluid after crosslinking could reach 348 mPas, and the viscosity decreased to about 200 mPas as when the temperature increased to 110 ℃; at 130 ℃ for 170s -1 The lower shearing is carried out for 120min, the viscosity of the fracturing fluid base fluid is always kept above 200 mPa.s, the rheological property is good, and the fracturing fluid base fluid obtained in the examples 4-5 has good fracturing capacity and good temperature resistance.
TABLE 2
| Category(s) | Gel breaking time min | Viscosity of gel breaking solution mPa.s | Content of residue mg/L |
| Example 1 | 70 | 3 | 325 |
| Example 2 | 25 | 3 | 262 |
| Example 3 | 20 | 2 | 256 |
| Example 7 | 200 | 9 | 426 |
| Example 8 | 110 | 6 | 334 |
| Comparative example 1 | 420 | 9 | 679 |
| Comparative example 2 | 130 | 6 | 568 |
TABLE 3 Table 3
As can be seen from tables 2 and 3:
1. compared with comparative examples 1-2, the fracturing fluid systems of examples 1-5 of the invention have low viscosity of the gel breaking fluid after gel breaking, low residue content, less than 30% of damage rate of the fracturing fluid system to core matrix or core fracture permeability and low damage to reservoir;
2. when the weighting agent is included in the fracturing fluid base fluid, the quantity of the gel breaker needs to be correspondingly adjusted to achieve effective gel breaking of the fracturing fluid system, and when the content of the weighting agent is 20%, the mass of the gel breaker is correspondingly adjusted to be 0.15-0.2% of the mass of the fracturing fluid base fluid.
The fracturing method in one embodiment of the invention comprises the following steps:
1. mixing 3.78t of guanidine gum, 18.90t of potassium chloride, 0.24t of citric acid, 9.45t of cleanup additive, 9.45t of demulsifier, 4.73t of temperature stabilizer, 0.95t of bactericide, 47.25t of waterproof locking agent, 1.89t of pH regulator and 848.35t of water to obtain a fracturing fluid base fluid;
2. mixing 3.78t of cross-linking agent with 3.78t of pH regulator to obtain a cross-linking component;
3. mixing the fracturing fluid base fluid obtained in the step 1 with the crosslinking component obtained in the step 2 to obtain a gel system;
4. and (3) mixing the gel in the step (3) with 400kg of gel breaker to obtain a fracturing fluid system.
5. Adding the fracturing fluid system obtained in the step 4 into a well shaft A for fracturing construction, wherein the fracturing construction curve is shown in figure 5, and the maximum discharge capacity is 5.7m during fracturing construction 3 Per min, maximum pump pressure 105.3MPa, squeeze into stratum liquid 1110.81m 3 (wherein squeeze into fracturing fluid System 836m 3 The rest is slick water);
wherein, the well A has a drilling depth of 6930m, the target layer is a chalk series Bashky group, the stratum pressure coefficient is 1.83, the bottom hole temperature is 130.6 ℃, and the high-pressure fracture type tight sandstone condensate gas reservoir with ultra-deep high temperature is provided. Before fracturing modification of the well A, a 3mm oil nozzle is used for open injection, the oil pressure is 43.392MPa, and the gas production during fracture is 46767m 3 1.23m of folded daily oil 3 。
After the fracturing construction is finished, the pressure at the wellhead is measured to be reduced from 76.1MPa to 63.9MPa, and the pressure drop is obvious; after the fracturing construction is completed, performing flowback test on the fracturing fluid system for 370 hours, wherein the flowback efficiency is 74.62%; after the fracturing transformation is completed, 7mm oil nozzles are used for open-flow production, the oil pressure is 79.721MPa, and the daily gas yield is 514521m 3 Daily oil production 41m 3 Converted unobstructed flow to 203.9X104 m 3 . The production test is carried out for 406 days, and the average daily gas production is 59.36 multiplied by 104m 3 Accumulated gas 2.41×108m 3 The production is stable, and the curve of the production test conditions after the fracturing reformation of the well A is completed is shown in figure 6. From this, it can be seen that: the fracturing method can obviously improve the oil gas exploitation efficiency, ensures stable and efficient oil gas exploitation, and has high flowback efficiency of a fracturing fluid system and small influence on a reservoir.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (3)
1. A fracturing fluid system, characterized in that the fracturing fluid system comprises a fracturing fluid base fluid, a crosslinking component and a breaker;
wherein the mass of the crosslinking component is 0.8% of the mass of the fracturing fluid base fluid;
the mass of the gel breaker is 0.04-0.2% of the mass of the fracturing fluid base fluid;
the base fracturing fluid comprises, by mass, 0.4% of guanidine gum, 5% of a waterproof locking agent, 1% of a cleanup additive, 0.2% of a pH regulator, 0.025% of citric acid, 1% of a demulsifier, 2-20% of a weighting agent, 0.5% of a temperature stabilizer, 0.1% of a bactericide and the balance of water;
the crosslinking component comprises a crosslinking agent and a pH regulator, wherein the mass ratio of the crosslinking agent to the pH regulator is 1:1, a step of;
the guanidine gum is selected from super modified guanidine gum JK101 of Kunshan of petrochemical company in China;
the waterproof locking agent is selected from methanol;
the cleanup additive is selected from fluorocarbon DJ-02 which is a cleanup additive for fracture acidizing of the Korla new Kate oilfield chemical technology Co., ltd;
the pH regulator is selected from organic alkali ZYT-B of a crosslinking regulator for fracturing of the Korla new Kate oilfield chemical technology Co., ltd;
the breaker is selected from a capsule breaker ammonium persulfate FRC-90B for fracturing of Beijing family Maishi oilfield chemistry agent technology Co-Ltd;
the cross-linking agent is selected from organic boron ZYT-A used for fracturing of the Korla new Kate oilfield chemical technology Co., ltd;
the demulsifier is selected from demulsifier propylene oxide DJ-10 for fracture acidizing of Korla New Kate oilfield chemical technology Co., ltd;
the weighting agent is selected from potassium chloride;
the temperature stabilizer is selected from the temperature stabilizer sulfite DJ-14 for fracturing of the Korla new Kate oilfield chemical technology Co., ltd;
the bactericide is selected from formaldehyde.
2. A fracturing method using the fracturing fluid system of claim 1, comprising the steps of:
mixing the fracturing fluid base fluid with a crosslinking component to obtain a gel system;
mixing the gel system with a gel breaker to obtain the fracturing fluid system;
the fracturing fluid system is added to the wellbore.
3. A fracturing method using the fracturing fluid system of claim 1, comprising the steps of:
mixing the fracturing fluid base fluid with a crosslinking component to obtain a gel system;
adding the gel system into a well bore;
the breaker is added to the wellbore.
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