CN114525123A - Slow-release acid and preparation and application thereof - Google Patents
Slow-release acid and preparation and application thereof Download PDFInfo
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- CN114525123A CN114525123A CN202011318869.2A CN202011318869A CN114525123A CN 114525123 A CN114525123 A CN 114525123A CN 202011318869 A CN202011318869 A CN 202011318869A CN 114525123 A CN114525123 A CN 114525123A
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- 239000002253 acid Substances 0.000 title claims abstract description 59
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 239000000126 substance Substances 0.000 claims abstract description 46
- 239000011973 solid acid Substances 0.000 claims abstract description 41
- 238000013268 sustained release Methods 0.000 claims abstract description 34
- 239000012730 sustained-release form Substances 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 26
- 238000009835 boiling Methods 0.000 claims abstract description 19
- 239000000839 emulsion Substances 0.000 claims description 25
- FPAFDBFIGPHWGO-UHFFFAOYSA-N dioxosilane;oxomagnesium;hydrate Chemical compound O.[Mg]=O.[Mg]=O.[Mg]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O FPAFDBFIGPHWGO-UHFFFAOYSA-N 0.000 claims description 20
- BIVUUOPIAYRCAP-UHFFFAOYSA-N aminoazanium;chloride Chemical compound Cl.NN BIVUUOPIAYRCAP-UHFFFAOYSA-N 0.000 claims description 15
- 239000000460 chlorine Substances 0.000 claims description 15
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 14
- 229910052801 chlorine Inorganic materials 0.000 claims description 14
- 239000000203 mixture Substances 0.000 claims description 6
- 239000010410 layer Substances 0.000 claims description 4
- 239000003208 petroleum Substances 0.000 claims description 4
- FDRCDNZGSXJAFP-UHFFFAOYSA-M sodium chloroacetate Chemical compound [Na+].[O-]C(=O)CCl FDRCDNZGSXJAFP-UHFFFAOYSA-M 0.000 claims description 4
- 239000000454 talc Substances 0.000 claims description 4
- 229910052623 talc Inorganic materials 0.000 claims description 4
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- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 2
- 235000019738 Limestone Nutrition 0.000 claims 1
- 239000010459 dolomite Substances 0.000 claims 1
- 229910000514 dolomite Inorganic materials 0.000 claims 1
- 239000006028 limestone Substances 0.000 claims 1
- 239000012530 fluid Substances 0.000 abstract description 57
- 230000002378 acidificating effect Effects 0.000 abstract description 15
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- 239000012528 membrane Substances 0.000 abstract description 9
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- 238000010008 shearing Methods 0.000 abstract description 5
- 230000003111 delayed effect Effects 0.000 abstract description 4
- 238000005086 pumping Methods 0.000 abstract description 4
- 238000005507 spraying Methods 0.000 abstract description 2
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- 239000002245 particle Substances 0.000 description 16
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- 206010017076 Fracture Diseases 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
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- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000011259 mixed solution Substances 0.000 description 6
- 229920001328 Polyvinylidene chloride Polymers 0.000 description 5
- 229910001424 calcium ion Inorganic materials 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- -1 hydroxide ions Chemical class 0.000 description 5
- 239000005033 polyvinylidene chloride Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 4
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- 230000015572 biosynthetic process Effects 0.000 description 4
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- 239000011435 rock Substances 0.000 description 4
- 208000013201 Stress fracture Diseases 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000000499 gel Substances 0.000 description 3
- 229920013818 hydroxypropyl guar gum Polymers 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 125000005587 carbonate group Chemical group 0.000 description 2
- NEHMKBQYUWJMIP-UHFFFAOYSA-N chloromethane Chemical compound ClC NEHMKBQYUWJMIP-UHFFFAOYSA-N 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 239000003431 cross linking reagent Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000011049 filling Methods 0.000 description 2
- LIAWOTKNAVAKCX-UHFFFAOYSA-N hydrazine;dihydrochloride Chemical compound Cl.Cl.NN LIAWOTKNAVAKCX-UHFFFAOYSA-N 0.000 description 2
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- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229920002907 Guar gum Polymers 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 229910017852 NH2NH2 Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
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- 229910052796 boron Inorganic materials 0.000 description 1
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- 238000003889 chemical engineering Methods 0.000 description 1
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- 239000007888 film coating Substances 0.000 description 1
- 238000009501 film coating Methods 0.000 description 1
- 239000008398 formation water Substances 0.000 description 1
- 239000000665 guar gum Substances 0.000 description 1
- 235000010417 guar gum Nutrition 0.000 description 1
- 229960002154 guar gum Drugs 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 235000015110 jellies Nutrition 0.000 description 1
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- 229910001425 magnesium ion Inorganic materials 0.000 description 1
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- 230000007935 neutral effect Effects 0.000 description 1
- 230000020477 pH reduction Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
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- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Substances [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 1
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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
- C09K8/72—Eroding chemicals, e.g. acids
- C09K8/74—Eroding chemicals, e.g. acids combined with additives added for specific purposes
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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
- C09K8/54—Compositions for in situ inhibition of corrosion in boreholes or wells
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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
- C09K8/72—Eroding chemicals, e.g. acids
- C09K8/725—Compositions containing polymers
-
- 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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
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- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
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- Environmental & Geological Engineering (AREA)
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Abstract
The invention provides a slow-release acid and preparation and application thereof. The sustained-release acid consists of an acid substance and a sustained-release substance, wherein the mass ratio of the acid substance to the sustained-release substance is (10:2.2) - (10: 6). The slow-release acid is prepared by adopting a boiling spraying method. The solid acid capable of delaying release of acidity provided by the invention has good delayed release acidity, temperature resistance and shearing resistance, is pumped into a stratum along with a fracturing fluid in a fracturing process, is coated with an inert outer membrane outside, ensures that no acidic substance is released in a ground pumping process and a fracturing initial stage, does not corrode fracturing equipment and a pipe column, and simultaneously ensures that the viscosity and sand carrying performance of the fracturing fluid.
Description
Technical Field
The invention relates to the field of oil exploitation, in particular to a slow-release acid and preparation and application thereof.
Background
The hydraulic fracturing technology, a process for improving the seepage characteristics of oil reservoirs, is an important process measure for increasing the production of oil and gas wells and increasing the injection of water injection wells. It uses a ground high-pressure pump set to inject high-viscosity liquid into well at a discharge rate greatly exceeding the absorption capacity of stratum, and then forms high pressure near the bottom of well. After this pressure exceeds the formation stress near the bottom of the well and the tensile strength of the rock, a fracture is formed in the formation. The injection of the proppant-laden liquid into the slots is continued, extending the slots forward and filling with proppant. Thus, a sand filling crack which is long enough and has certain height and width can be formed after the pump is stopped, and the flow conductivity of the oil-gas layer is improved. Along with the continuous use of unconventional reservoirs, the permeability of reservoirs facing oil and gas field development is lower and higher, the development difficulty is higher and higher, particularly for shale reservoirs, the permeability is as low as nanometer level, the problem that low permeability, particularly ultra-low permeability reservoirs are difficult to use can be solved by the large-scale horizontal well fracture network fracturing technology, and the method is a technical core for realizing the economic and effective use of the unconventional reservoirs. The conventional hydraulic fracturing technology is that injected fracturing fluid is neutral or alkalescent, which is mainly characterized in that the fracturing fluid crosslinking fluid needs alkalescent crosslinking environment, and a certain amount of hydroxide ions can provide enough crosslinking ions to ensure the viscosity and sand carrying performance of the guar gum fracturing fluid. Some carbonate rocks, clay minerals and calcium and magnesium ions in formation water in the formation are extremely easy to cause damage and form blockage in the weak alkaline liquid environment. For some alkali-sensitive reservoirs, the damage of the fracturing fluid can greatly reduce the pressure and increase the yield, so that the pH value of the fracturing fluid is reduced after the fracturing fluid enters a crack, the acidity of the fracturing fluid is improved, the damage of the alkali-sensitive reservoir is favorably reduced, the fixed-point acidification in the formation is realized, carbonate particles in the reservoir are corroded, various seepage flow of main cracks, microcracks and reservoir matrixes is established, the improvement effect after the fracturing is improved, the recovery ratio is further improved, and the yield of a single well is greatly improved.
And the conventional acid liquor is directly added into the fracturing fluid, so that the fracturing fluid can be subjected to rapid gel breaking and viscosity reduction, the joint-making and sand-carrying effects cannot be guaranteed, and meanwhile, the acid liquor can also corrode ground fracturing equipment and a pipe column, so that the construction risk is increased.
Disclosure of Invention
It is an object of the present invention to provide a slow-release acid;
the invention also aims to provide a preparation method of the slow-release acid;
the invention further aims to provide application of the slow-release acid.
In order to achieve the above object, in one aspect, the present invention provides a sustained-release acid, wherein the sustained-release acid is composed of a solid acid and a sustained-release substance, and the mass ratio of the solid acid to the sustained-release substance is (10:2.3) - (10: 6).
According to some embodiments of the invention, the solid acid is selected from hydrazine hydrochloride, citric acid and ethylenediaminetetraacetic acid.
According to some embodiments of the invention, wherein the slow release substance is selected from a water slow dissolving substance and/or an inert wear destroying substance.
The water-slowly-soluble substance refers to a substance capable of slowly decomposing in water, which may be a substance capable of slowly decomposing in water, which is conventional in the art, and according to some embodiments of the present invention, the water-slowly-soluble substance is selected from one or more of acrylic resin IV, ethyl cellulose, polyvinylpyrrolidone, and polyvinyl chloride.
The inert abrasion-breaking substance refers to a substance which achieves a slow release effect by friction with the outside so as to gradually wear off the substance, and can be an inert abrasion-breaking substance which is conventional in the art, and according to some embodiments of the present invention, the inert abrasion-breaking substance is a mixture of talcum powder and a chloro-meta-emulsion.
It is understood that, in the preparation of the sustained-release acid, one skilled in the art can select a suitable sustained-release substance according to the form of the acid.
According to some embodiments of the present invention, the ratio of talc to the partial chlorine emulsion satisfies the following condition: when the mass of the talcum powder is 100g, the volume of the chlorine partial emulsion is 600-1000 ml.
It is understood that when the mass of the talc powder is 100g, the volume of the polyvinylidene chloride emulsion is 600-1000ml, which means that the ratio of the mass volumes of the talc powder and the polyvinylidene chloride emulsion satisfies the ratio range, but does not mean that the dosage of the talc powder and the polyvinylidene chloride emulsion is necessarily the range. For example, when the talc powder is 1g, the volume of the partial chlorine emulsion is 6-10 ml.
According to some embodiments of the present invention, the ratio of talc to the partial chlorine emulsion satisfies the following condition: when the mass of the talcum powder is 100g, the volume of the chlorine partial emulsion is 800 ml.
The sustained release acid of the present invention may be a mixture of a solid acid and a sustained release material, and according to some embodiments of the present invention, the sustained release acid comprises a core layer composed of the solid acid and a shell layer composed of the sustained release material.
According to some specific embodiments of the invention, the core layer has a mass percentage of 80-90% based on 100% of the total mass of the sustained-release acid.
Specifically, the slow-release acid comprises the following raw materials in parts by mass:
1 kg of hydrazine hydrochloride;
25-35 g of talcum powder;
200-500 ml of the chlorine partial emulsion.
In the above delayed release acid sustained release acid, the molecular formula of the hydrazine hydrochloride particle is NH2NH22HCl, also known as hydrazine dihydrochloride, hydrazine hydrochloride, hydrazine dihydrochloride. The product can be hydrazine hydrochloride product of Wuhan co-creation science and technology Limited company, and has a product number of 216194.
Among the above sustained-release acids which can delay the release of acidity, talc is conventionally commercially available.
In the sustained-release acid capable of delaying release of acidity, the polyvinylidene chloride emulsion is vinyl chloride-vinylidene chloride copolymer emulsion and milky emulsion, is a novel polymer synthetic latex, and can be selected from Shanghai Tianyin chemical engineering and science company products.
On the other hand, the invention also provides a preparation method of the sustained-release acid, wherein the sustained-release acid is prepared by adopting a boiling spraying method.
According to some specific embodiments of the invention, the method comprises preparing the sustained-release acid by a boiling spray method at a temperature of 35-45 ℃ (the temperature of a boiling furnace is set to be 35-45 ℃).
According to some embodiments of the present invention, wherein the sustained release acid is prepared according to a prior art film forming process.
According to some embodiments of the invention, wherein the slow release acid is prepared by: and (3) putting the solid acid granules into a boiling spray drying granulator at the temperature of between 35 and 45 ℃, and introducing a slow release substance to prepare the solid acid granules capable of delaying the release of acidity.
According to some embodiments of the invention, wherein the preparing of the sustained release acid comprises: and (3) putting the solid acid granules into a boiling spray drying granulator at the temperature of between 35 and 45 ℃, and introducing a mixed solution of talcum powder and metachloro-emulsion to prepare the solid acid granules capable of delaying the release of acidity.
The slow-release acid is a solid acid capable of delaying the release of acidic substances, and comprises the following components: the inner part mainly consists of hydrazine hydrochloride particles, the outer layer inert film mainly comprises talcum powder and chlorine meta-emulsion, the film coating process mainly adopts a boiling spray drying granulator, the temperature is set to be 35-45 ℃, firstly, a proper amount of hydrazine hydrochloride crystal particles are placed into the boiling spray drying granulator, the mixed liquid of the talcum powder and the chlorine meta-emulsion is slowly introduced under the boiling condition for 1 hour, and finally, solid acid particles capable of delaying release of acidity are prepared.
The preparation method can keep the acidity of the hydrazine hydrochloride from being damaged, the chlorine partial emulsion can quickly form a film at the temperature of between 35 and 45 ℃, an inert outer film is formed to wrap the hydrazine hydrochloride particles, and the preparation method has good sealing property, temperature resistance and shearing resistance, and does not release acidic substances at normal temperature and normal pressure.
In still another aspect, the invention also provides the application of the slow-release acid in the fracturing of the petroleum reservoir.
The slow-release acid of the invention can be used for preparing a fracturing fluid pad fluid, for example, the invention can adopt the existing conventional fracturing fluid pad fluid to be mixed with the composition of the invention to prepare the required pad fluid, and according to some embodiments of the invention, the pad fluid consists of the following components in parts by weight: 0-0.12 part of HPG hydroxypropyl guar gum, 1-2 parts of KCl and 5-10 parts of NaNO 26 to 12 parts of NH4Cl, 1-4 parts of slow-release acid and 100 parts of water.
NaNO contained in the fracturing fluid-containing pad fluid2And NH4Cl is a substance which can generate chemical reaction under acidic condition, and NaNO is generated under the condition that the pH value is lower than 52And NH4The Cl can react to form hydrogen and release heat, with the reaction decreasing in pH and increasing in temperature.
When the slow-release acid is used for modifying a reservoir stratum, the fracturing fluid pad fluid added with any one of the compositions can be injected into the stratum, and after the fracturing fluid pad fluid reaches a reservoir stratum micro-crack and undergoes a chemical reaction to generate gas, the fracturing fluid is injected.
According to some embodiments of the invention, the method comprises selecting the release-delaying substance according to the depth and location of the reservoir microfracture, such that when the front pad reaches the reservoir microfracture, the release-delaying acid releases acid which reacts with the chemical agent capable of releasing gas to generate gas.
According to some embodiments of the present invention, the method includes controlling the pumping rate and the construction pressure of the pad fluid, during the fracturing process, the chemical agent can enter the front end of the fracture and partially enter the reservoir matrix and the micro-fracture of the reservoir along with the pad fluid, controlling the reaction time of the chemical agent according to the time arrangement of the fracturing design, after the fracturing process, controlling the initiation of the chemical reaction, the chemical agent can rapidly release energy, the volume expansion increases the local pressure, the local stress field is changed, the fracture is further extended in a pulse mode, and a new fracture is generated.
In conclusion, the invention provides a slow-release acid and preparation and application thereof. The technical scheme of the invention has the following advantages:
the solid acid capable of delaying release of acidity provided by the invention has good delayed release acidity, temperature resistance and shearing resistance, is pumped into a stratum along with a fracturing fluid in a fracturing process, and is wrapped with an inert outer membrane outside, so that acidic substances are not released in a ground pumping process and a fracturing initial stage, a fracturing device and a pipe column are not corroded, the viscosity and sand carrying performance of the fracturing fluid are ensured, after the fracturing fluid enters a reservoir, the inert outer membrane is broken to release the acidic substances to reduce the pH value of the fracturing fluid under the conditions of high pressure and friction of the stratum, the damage of the fracturing fluid to the stratum is reduced, the fracturing modification effect of an unconventional compact reservoir is improved, and the yield of oil gas is increased. The slow-release acid technology is applied to a compact oil horizontal well of a western oil field in China for 1 well, and the yield of a single well after pressing is increased from 2.7 tons/day to 10.8 tons/day.
Drawings
FIG. 1 is a graph of pH as a function of time for example 1.
FIG. 2 is a graph of pH as a function of time for example 2.
FIG. 3 is a graph of pH as a function of time for example 3.
FIG. 4 is a graph showing the change in calcium ion concentration with time in example 3.
FIG. 5 is a viscosity change curve of a system containing retarded acid fracturing fluid.
Detailed Description
The following detailed description is provided for the purpose of illustrating the invention and the resulting beneficial effects, and is not intended to limit the scope of the invention.
Example 1
The embodiment provides a solid acid capable of delaying release of acidity, which comprises the following raw materials in parts by mass:
1 kg of hydrazine hydrochloride;
25g of talcum powder;
200ml of chlorine partial emulsion.
The hydrazine hydrochloride in this example was manufactured by Wuhan Co-creation science and technology, Inc., product number is 216194, and the Chloromethane emulsion was manufactured by Shanghai Tianyin chemical industry and technology, Inc.
25g of talcum powder and 200ml of chlorine partial emulsion are mixed and stirred evenly to form mixed liquid.
A method of preparation comprising the steps of: putting hydrazine hydrochloride particles into a boiling spray drying granulator at the temperature of 35 ℃, keeping the boiling state, introducing mixed solution of 6.67ml/min of talcum powder and chlorometaemulsion into the boiling spray drying granulator, and after all mixed solution of the talcum powder and the chlorometaemulsion is completely injected, keeping the boiling state at the temperature of 35 ℃ for drying for 20min, and finally preparing solid acid particles capable of delaying the release of acidity.
The solid acid capable of delaying the release of acidity prepared in example 1 was subjected to pH test in water: weighing 10g of the prepared solid acid capable of delaying release of acidity by using an electronic balance, dissolving the solid acid in 100ml of water, placing the water in a water area of 60 ℃, selecting a pH meter of Mettler-Torlington company, testing the pH value once every 1min, taking out solid acid particles after 30min, crushing the particle parts by using a rolling method, pouring the crushed particles into a beaker, keeping the beaker in the water area of 60 ℃, testing the pH value once every 1min, testing for 20min, recording the change of the pH value of the solution at different times, and drawing a curve shown in figure 1. The experimental result shows that the pH value of the solution is kept constant for 6.5-7 in the first 30min, which indicates that the solid acid inert outer membrane can well protect internal substances from being dissolved in water to release acidic substances, and after the solid acid inert outer membrane is rolled by external force, the pH value of the solution is rapidly reduced to 1 at the lowest, which indicates that the internal hydrazine hydrochloride can rapidly release acidity after being dissolved in water to reduce the pH value of the solution.
Example 2
The embodiment provides a solid acid capable of delaying release of acidity, which comprises the following raw materials in parts by mass:
1 kg of sodium chloroacetate;
35g of talcum powder;
450ml of chlorine partial emulsion.
The sodium chloroacetate in this example is a commercially available product, and the stone powder and 450ml of the polyvinylidene chloride emulsion are mixed and stirred uniformly to form a mixed solution.
A method of preparation comprising the steps of: and (2) putting the sodium chloroacetate particles into a boiling spray drying granulator at the temperature of 45 ℃, keeping the boiling state, introducing a mixed solution of 10ml/min of talcum powder and the chlorometaemulsion into the boiling spray drying granulator, and after all the mixed solution of the talcum powder and the chlorometaemulsion is completely injected, keeping the boiling drying at the temperature of 45 ℃ for 20min, and finally preparing the solid acid particles capable of delaying the release of the acidity.
The solid acid capable of delaying the release of acidity prepared in example 2 was subjected to pH test in water: weighing 10g of the prepared solid acid capable of delaying release of acidity by using an electronic balance, dissolving the solid acid in 100ml of water, placing the water in a water area at 80 ℃, selecting a pH meter of Mettler-Torlington company, testing the pH value once every 1min, taking out solid acid particles after 30min, crushing the particle parts by using a rolling method, pouring the crushed particles into a beaker, keeping the beaker in the water area at 80 ℃, testing the pH value once every 1min, testing for 20min, recording the change of the pH value of the solution at different times, and drawing a curve shown in figure 2. The experimental result shows that the pH value of the solution is kept constant for 6.5-7 in the first 30min, which indicates that the solid acid inert outer membrane can well protect internal substances from being dissolved in water to release acidic substances, and after the solid acid inert outer membrane is rolled by external force, the pH value of the solution is rapidly reduced to 1 at the lowest, which indicates that the internal hydrazine hydrochloride can rapidly release acidity after being dissolved in water to reduce the pH value of the solution.
Example 3
Simulating that the outer membrane is broken and acidic substances are released after the solid acid capable of delaying the release of acidity is extruded by external force in a crack, referring to a test method of an industry standard SY/T6526-2002 dynamic reaction rate measuring method of hydrochloric acid and carbonate rock, taking 200g of the solid acid capable of delaying the release of acidity prepared in the embodiment 1 uniformly, taking 2 carbonate core plates with the specification of 15.40mm multiplied by 50.80mm multiplied by 25.40mm (deviation is +/-0.2 mm), testing the quality of the core plates under a drying condition, uniformly laying 200g of the solid acid capable of delaying the release of acidity between the two core plates, placing the core plates in an acid rock reaction diversion test experimental device, setting the pressure in the core holder to be 40MPa, setting the temperature to be 60 MPa, injecting water with the temperature of 60 ℃ at the flow rate of 1ml/min, testing the pH value of liquid flowing out of the device by using a pH meter, sampling is carried out at intervals of 5min, the obtained liquid sample is diluted by 10 times, and the change value of calcium ions in the effluent liquid is tested by an ion chromatograph for 2 h. The experimental results are shown in fig. 3 and 4, and it can be seen from the experimental results of fig. 3 and 4 that, in the environment of 40Mpa, the pH value of the effluent gradually decreases, the calcium ion concentration in the water gradually increases, which indicates that the internal acidic substance is rapidly released under the external force extrusion of the two core plates by the solid acid capable of delaying release of acidity, in the acidic environment, the carbonate in the carbonate core gradually dissolves to release calcium ions, after the experiment, the corrosion points can be seen by observing the contact surface of the two core plates, and the mass difference of the core plates before and after the experiment can indicate that 11.72% of the carbonate is dissolved and corroded. The experiment result shows that the solid acid capable of delaying release of acidity can realize quick release in a high-pressure environment in a fracture, reduce the pH value, dissolve carbonate in a stratum and improve the fracture corrosion degree of the fracturing fluid. And the complexity of cracks is improved.
Example 4
The embodiment provides a slow-release acid and a preparation method thereof, the solid acid capable of delaying release of acidity of the slow-release acid has good delayed release acidity, temperature resistance and shearing resistance (see fig. 5), the solid acid is pumped into a stratum along with a fracturing fluid in a fracturing process, an inert outer membrane is wrapped outside the solid acid, so that acidic substances are not released in a ground pumping process and a fracturing initial stage, fracturing equipment and a pipe column are not corroded, and meanwhile, the viscosity and sand carrying performance of the fracturing fluid are guaranteed.
5g of the solid slow-release acid prepared in the example 1 is mixed with hydroxypropyl guar fracturing fluid to test the viscosity retention rate under the conventional condition, and the hydroxypropyl guar concentration fracturing fluid comprises the following components in parts by volume:
95.1 parts of hydroxypropyl guar solution HPG
0.5 part of 5 percent NaOH solution
0.4 part of BCL-81 organic boron crosslinking agent
The preparation method of the fracturing fluid provided by the embodiment comprises the following steps:
according to the water: hydroxypropyl guar 99.82: 0.18, adding hydroxypropyl guar gum into water under the condition of stirring, and stirring for 20 minutes to uniformly mix to obtain the hydroxypropyl guar gum aqueous solution. Standing at 30 ℃ for 4 hours to obtain a fracturing fluid base fluid;
and (3) sequentially adding the NaOH solution and the slow-release acid prepared in the embodiment 1 into the base fluid of the fracturing fluid, uniformly stirring, then adding the cross-linking agent, and uniformly stirring and mixing until the fracturing fluid gel containing the slow-release acid is formed.
The performance of the jelly fracturing fluid provided by the embodiment is detected according to the detection standard of SY/T5107-2005 'evaluation method of water-based fracturing fluid', and the experimental result is shown in figure 5. The temperature resistance and the shear resistance of the gel fracturing fluid of the embodiment are tested by adopting an RS600 rheometer, the test temperature is 120 ℃, and the shear rate is 170s-1Shearing under conditionsThe viscosity of the fracturing fluid can be kept above 100 mPa.s after 90 minutes, the fracturing fluid can be seen to keep a better viscosity retention rate according to a test result, the slow-release acid shell does not damage the acidic substance in the fracturing fluid and does not release the acidic substance under the condition of continuous stirring for 120 minutes (if the acidic substance releases the fracturing fluid, the fracturing fluid can be rapidly broken, and the viscosity of the fracturing fluid is lower than 5mPa.s), and the result is shown in FIG. 5. The viscosity of the fracturing fluid is 170s-1After the fracturing fluid is sheared for 90 minutes under the condition, the viscosity of the fracturing fluid is kept above 100 mPas, and the fracturing fluid is considered to keep good sand carrying performance in the stratum without causing sand removal.
Claims (10)
1. The sustained-release acid consists of a solid acid and a sustained-release substance, wherein the mass ratio of the solid acid to the sustained-release substance is (10:2.3) - (10: 6).
2. The sustained release acid of claim 1, wherein the solid acid is selected from the group consisting of hydrazine hydrochloride, sodium chloroacetate, and ethylenediaminetetraacetic acid, in combination of one or more.
3. The sustained release acid of claim 1, wherein the sustained release substance is selected from an inert wear-destroying substance, and/or a water-slowly soluble substance.
4. The slow release acid of claim 3, wherein the inert wear-destroying substance is a mixture of talc and a chloropartial emulsion; the proportion of the talcum powder and the chlorine partial emulsion meets the following conditions: when the mass of the talcum powder is 100g, the volume of the chlorine partial emulsion is 600-1000 ml.
5. The slow release acid of claim 3, wherein the water-slowly soluble substance is selected from one or more of acrylic resin IV, ethyl cellulose, polyvinylpyrrolidone, and polyvinyl chloride.
6. The sustained-release acid according to any one of claims 1 to 5, wherein the sustained-release acid comprises a core layer composed of a solid acid and a shell layer composed of a sustained-release substance.
7. The method for preparing the sustained-release acid according to any one of claims 1 to 6, wherein the sustained-release acid is prepared by a boiling spray method.
8. The preparation method according to claim 7, wherein the method comprises preparing the sustained-release acid by a boiling spray method at a temperature of 35-45 ℃.
9. Use of the slow release acid of any one of claims 1 to 6 in fracturing of a petroleum reservoir.
10. Use according to claim 9, wherein the petroleum reservoir is a petroleum reservoir containing sandstone, limestone and dolomite.
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