CN107286918B - Efficient well flushing fluid for well flushing of low-permeability sandstone oil reservoir - Google Patents
Efficient well flushing fluid for well flushing of low-permeability sandstone oil reservoir Download PDFInfo
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- CN107286918B CN107286918B CN201710566328.3A CN201710566328A CN107286918B CN 107286918 B CN107286918 B CN 107286918B CN 201710566328 A CN201710566328 A CN 201710566328A CN 107286918 B CN107286918 B CN 107286918B
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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
- C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
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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
- C09K2208/12—Swell inhibition, i.e. using additives to drilling or well treatment fluids for inhibiting clay or shale swelling or disintegrating
Abstract
The invention provides a high-efficiency well flushing fluid suitable for a low-permeability sandstone oil reservoir, which comprises 0.1-1.0% of a waterproof locking agent, 0.5-3.0% of an anti-swelling agent, 5.0-10.0% of a cosolvent and the balance of water. The efficient well flushing fluid can change the wettability of a low-permeability sandstone reservoir from strong water humidity to weak water humidity, and eliminate the self-absorption capillary force of the reservoir; the emulsion has ultralow oil-water interfacial tension and strong anti-emulsification capability, and can effectively reduce water lock and allergy damage; has excellent clay anti-swelling performance, can effectively reduce water-sensitive damage and protect an oil-gas layer to the maximum extent.
Description
Technical Field
The invention relates to a well flushing fluid, in particular to a well flushing fluid suitable for reservoir protection of a low-permeability sandstone reservoir.
Background
The well flushing operation is one of the common maintenance measures of an oil well, but a low-permeability oil reservoir generally has the characteristics of low stratum pressure level, strong oil layer sensitivity and the like, when the well flushing operation is carried out by utilizing the conventional well flushing liquid, the well flushing liquid easily enters a reservoir stratum to cause water lock, emulsification, water sensitivity and other damages to the reservoir stratum, and a large number of indoor experiments show that the damage generated when the well flushing liquid invades into the stratum is mainly water lock, and simultaneously, hydration expansion, oil-water emulsification and the like exist. Once these reservoir injuries are formed, they are difficult to remove, which in turn makes the recovery of the well production difficult or the recovery cycle long after the well is washed, and in severe cases, can lead to the well lying.
At present, a well flushing liquid system taking a waterproof locking agent and a clay anti-swelling agent as main treating agents is mainly used for reducing the invasion degree of a well flushing liquid, removing water locking damage, inhibiting clay hydration swelling and the like by adding a surfactant, but has the following two problems that an ① well flushing liquid system generally has insufficient interfacial tension reduction, poor emulsion prevention capability, poor hydration swelling inhibition effect and the like, and is difficult to meet the requirement of reservoir protection of a low-permeability reservoir, a ② well flushing liquid system is more in harm of drilling fluid to a gas layer, the well flushing liquid system related to well flushing of an oil well, conventional operation and the like is less, and meanwhile, the research on rock wettability is relatively less.
CN103351856A discloses a flushing fluid for removing damage of drilling fluid of low permeability sandstone gas layer and a preparation method thereof, wherein the flushing fluid comprises: the weight ratio of the surfactant is 0.05-0.1%, the weight ratio of the organic solvent chloroform is 8-10%, the weight ratio of the potassium formate is 5.0-6.0%, the weight ratio of the hydrogen peroxide is 0.6-0.8%, and the weight ratio of the hydrofluoric acid is 0.5-0.8%, so that the hypotonic sandstone gas reservoir is changed from strong hydrophilicity to weak hydrophilicity, the capillary force of the reservoir is eliminated, the reservoir is dissolved into a partial solid phase, the blockage is broken, the gas-water driving efficiency is improved, the solid phase damage is reduced, and the core permeability recovery rate is obviously improved. Although the well-flushing fluid can change the rock wettability to a certain extent, the well-flushing fluid mainly degrades high molecular polymers of drilling fluid invading into a gas layer, dissolves solid-phase particles of filtrate and reduces the damage of the filtrate to the gas layer.
CN103602326A discloses a novel efficient well-flushing fluid with an oil layer protection effect, a preparation method and an application thereof, wherein the well-flushing fluid is prepared by compounding methyl bis-hydroxyethyl carboxyethyl ammonium chloride, methanol, phenol amine resin polyoxyethylene polypropylene ether and hydroxylamine polyether amine. The flushing fluid can efficiently flush a well and protect a stratum at the same time, does not influence the normal production of an oil well, and has the effects of improving the yield, reducing the cost, remarkably improving the economic benefit and the like. However, the above-mentioned flushing fluids have not investigated the wettability of rock and can only reduce the interfacial tension to 10-2mN/m, the anti-emulsification capability is limited, and the anti-emulsification rate can only reach over 75 percent.
CN104449627A discloses an oil layer protection accelerator and a preparation method thereof, wherein the oil layer protection accelerator comprises the following components in percentage by weight: 0.1 to 1.0 percent of polyepichlorohydrin-dimethylamine, 0.5 to 2.0 percent of ammonium chloride, 0.1 to 0.5 percent of surfactant, 5 to 15 percent of ethanol and the balance of water. Although the oil layer protection accelerant can enable the anti-swelling rate to reach more than 92 percent, the surfactant can also enable the oil-water interfacial tension and the capillary resistance to be greatly reduced, but the rock wettability can not be changed from strong hydrophilicity to weak hydrophilicity, and the self-priming capillary force of a reservoir layer can not be eliminated.
Disclosure of Invention
In view of the problems, the invention provides a high-efficiency well flushing fluid for a low-permeability sandstone oil reservoir, which can change the wettability of the low-permeability sandstone oil reservoir from strong hydrophilicity to weak hydrophilicity, eliminate the self-priming capillary force of the reservoir, effectively reduce the oil-water interfacial tension, prevent oil-water emulsification, control the hydration expansion of clay minerals, and reduce the damage of the well flushing fluid to the low-permeability sandstone oil reservoir to the maximum extent while efficiently flushing the well.
The invention provides a high-efficiency well flushing fluid for a low-permeability sandstone reservoir, which is prepared from the following components in percentage by weight:
0.1 to 1.0 percent of waterproof locking agent;
0.5 to 3.0 percent of anti-swelling agent;
5.0 to 10.0 percent of cosolvent;
the balance being water.
Further preferably, the weight percentage ratio is as follows:
0.2 to 0.56 percent of waterproof locking agent;
1.5 to 2.8 percent of anti-swelling agent;
6.0 to 8.5 percent of cosolvent;
the balance being water.
Further preferably, the water-blocking agent is formed by compounding an anionic surfactant, a cationic surfactant and a nonionic surfactant, wherein the molar ratio of the anionic surfactant to the cationic surfactant to the nonionic surfactant is (0.4-0.6): (1-1.5): (1.2-1.5).
Further preferably, the anionic surfactant is one or a mixture of more of sodium oleate, sodium laurate, sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, the cationic surfactant is one or more of dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium chloride and bromo hexadecyl pyridine, and the nonionic surfactant is one or a mixture of more of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether.
Further preferably, the anti-swelling agent is polyether diamine.
Further preferably, the cosolvent is one or a mixture of methanol, ethanol and propanol.
The invention also provides a preparation method of the efficient well flushing liquid for the low-permeability sandstone oil reservoir, which comprises the steps of directly adding the waterproof locking agent and the cosolvent into water according to the mixture ratio, heating to 45-55 ℃, fully stirring for 1-2 hours, adding the anti-swelling agent after each treating agent is completely dissolved, and uniformly mixing to obtain the well flushing liquid.
The invention has the beneficial effects that: for a low-permeability sandstone reservoir, the low-permeability sandstone reservoir has the characteristics of low formation pressure, strong reservoir sensitivity, high capillary pressure, small pore roar and the like generally, and in the well flushing process, when the well flushing is carried out by using the conventional well flushing fluid, the well flushing fluid is easy to leak to the formation, and after the well flushing fluid enters the formation, the well flushing fluid has insufficient capacity of reducing the oil-water interfacial tension, preventing crude oil from emulsifying and inhibiting the hydration and expansion of clay, so that the reservoir is damaged. In order to ensure the smooth operation of well washing operation, reduce the amount of well washing liquid leaked to the stratum and how to more effectively reduce or eliminate the damage of the stratum after the well washing liquid is leaked to the stratum, the efficient well washing liquid and the preparation method thereof are introduced. The well flushing fluid has the following advantages:
(1) changing the reservoir rock surface wettability: the added waterproof locking agent can change the strong hydrophilicity of the rock surface of the low-permeability sandstone reservoir into weak hydrophilicity, eliminate capillary force and reduce the invasion degree of the flushing fluid.
(2) Effectively reducing the oil-water interfacial tension and stronger anti-emulsification capacity: the water-proof locking agent compounded in a specific proportion is added to ensure that the oil-water interfacial tension reaches 10-4mN/m, the milk prevention rate is more than or equal to 98 percent, and the damage of water lock and Jiamin can be reduced to the maximum extent.
(3) Inhibition of hydration swelling of clay minerals: the added polyether diamine anti-swelling agent has an anti-swelling rate of over 94 percent, and can effectively inhibit the swelling and dispersing effects of the clay.
Compared with the conventional well flushing fluid, the well flushing fluid has excellent water locking prevention, expansion prevention and emulsification prevention performances, is simple in fluid preparation, can reduce the damage of the well flushing fluid to a low-permeability sandstone oil reservoir to the maximum extent while efficiently flushing the well, and has a good application prospect.
Detailed Description
The technical idea of the present invention will be further explained and demonstrated by specific examples.
All raw materials used in the following examples are raw materials commonly used in the industry market, unless otherwise specified.
Example 1
The efficient well flushing fluid suitable for Jiangsu low-permeability sandstone oil reservoirs is prepared by mixing the following components:
0.2 part of waterproof locking agent, wherein 0.06 part of cationic surfactant cetyl trimethyl ammonium bromide, 0.08 part of anionic surfactant lauryl sodium sulfate and 0.06 part of nonionic surfactant fatty alcohol-polyoxyethylene ether;
2.0 parts of anti-swelling agent polyether diamine;
6.0 parts of cosolvent methanol;
the balance being water.
Directly adding the waterproof locking agent and the cosolvent into water according to the proportion, heating to 45-55 ℃, fully stirring for 1-2 hours, adding the anti-swelling agent after each treating agent is completely dissolved, and uniformly mixing to obtain the high-efficiency well flushing fluid suitable for the low-permeability sandstone oil reservoir.
Experiments such as the evaluation of water-lock damage of the high-efficiency flushing fluid are carried out indoors, and the indoor evaluation shows that the oil-water interfacial tension of the high-efficiency flushing fluid in the embodiment reaches 3.55 multiplied by 10-4The mN/m order of magnitude, the recovery rate of the permeability of the rock core is 97%, the anti-swelling rate is 95%, and the anti-emulsifying rate is 100%.
The wettability of the rock sample is measured by a self-priming method, and the water-wet index of the rock sample before and after treatment by the flushing fluid is reduced from 0.941 to 0.615, which shows that the flushing fluid can change strong hydrophilicity into weak hydrophilicity of a low-permeability sandstone oil reservoir, eliminate the self-priming capillary force of the reservoir and reduce the invasion degree of the flushing fluid.
Example 2
The efficient well flushing fluid suitable for Jiangsu low-permeability sandstone oil reservoirs is prepared by mixing the following components:
0.25 part of waterproof locking agent, wherein 0.065 part of cationic surfactant dodecyl trimethyl ammonium bromide, 0.087 part of anionic surfactant dodecyl benzene sulfonate and 0.098 part of nonionic surfactant alkylphenol polyoxyethylene;
2.5 parts of anti-swelling agent polyether diamine;
8.0 parts of cosolvent propanol;
the balance being water.
Directly adding the waterproof locking agent and the cosolvent into water according to the proportion, heating to 45-55 ℃, fully stirring for 1-2 hours, adding the anti-swelling agent after each treating agent is completely dissolved, and uniformly mixing to obtain the high-efficiency well flushing fluid suitable for the low-permeability sandstone oil reservoir.
Experiments such as the evaluation of water-lock damage of the high-efficiency flushing fluid are carried out indoors, and the indoor evaluation shows that the oil-water interfacial tension of the high-efficiency flushing fluid in the embodiment is 4.22 multiplied by 10-4The mN/m order of magnitude, the recovery rate of the permeability of the rock core is 99%, the anti-swelling rate is 94%, and the anti-emulsifying rate is 99%.
The self-priming method is adopted to measure the wettability of the rock sample, and the water-wet index of the rock sample before and after treatment by the flushing fluid is reduced from 0.962 to 0.727, which shows that the flushing fluid can change the strong hydrophilicity of the low-permeability sandstone reservoir into the weak hydrophilicity, eliminate the self-priming capillary force of the reservoir and reduce the invasion degree of the flushing fluid.
Comparative example 1
The well-flushing fluid for relieving damage of the drilling fluid of the ancient low-permeability sandstone gas layer in Changqing is prepared from the following components in percentage by weight:
the weight ratio of clean water to the weight ratio of clean water is 82.6 percent, the weight ratio of surfactant is 0.1 percent, the weight ratio of chloroform as an organic solvent is 10 percent, the weight ratio of potassium formate is 6.0 percent, the weight ratio of hydrogen peroxide is 0.8 percent, and the weight ratio of hydrofluoric acid is 0.5 percent, and the components are mixed to prepare the well-flushing fluid for removing the damage of the ancient low-permeability sandstone gas layer drilling fluid in Changqing.
The experimental performance according to the laboratory conditions of example 1 shows that the flushing fluid interfacial tension is 7.6X 10-3mN/m; the anti-swelling rate is 81 percent; the milk prevention rate is 90 percent; the core permeability recovery was 72%.
Comparative example 2
Reaction conditions are as follows:
reaction temperature: 40-45 DEG C
Reaction pressure: -0.08 to 0.15MPa
Reaction time: 1-2 h.
Feeding for producing 1000 parts of product:
the preparation process comprises the following steps:
1) according to the material ratio, under the condition of stirring at room temperature of 0.1Mpa, methyl dihydroxyethyl carboxyethylammonium chloride, phenol amine resin polyoxyethylene polypropylene ether and hydroxylamine polyether amine are successively added into water.
2) Slowly heating to 40-45 ℃ and continuously stirring for 0.5 h.
3) Adding methanol according to the proportion, and continuously stirring for 1h until the mixture is uniform to obtain the novel efficient well-flushing fluid for protecting the oil layer.
Experiments conducted under the laboratory conditions of example 1 showed that the new high efficiency flushing fluid interfacial tension of the protective reservoir was 9.8X 10-3mN/m; the anti-swelling rate is 86 percent; the milk prevention rate is 87%; the core permeability recovery was 95%.
Comparative example 3 (example selected from CN 104449627A)
The oil layer protection accelerator of the embodiment comprises the following components in percentage by weight:
1.0% of polyepichlorohydrin-dimethylamine, 2.0% of ammonium chloride, 0.5% of fluorocarbon surfactant, 15% of ethanol and the balance of water. The preparation method of the oil layer protection accelerator of the comparative example includes the following steps: 1) adding polyepichlorohydrin-dimethylamine, surfactant and ethanol into water which accounts for 60 percent of the mass of the oil layer protection accelerator according to the formula amount, and uniformly mixing to obtain a mixture; 2) and (2) adding the mixture obtained in the step 1) into ammonium chloride and the rest water according to the formula amount, and uniformly mixing to obtain the water-soluble polyurethane.
According to the experiment under the laboratory conditions of the example 1, the oil-water interfacial tension of the high-efficiency well flushing fluid is 16.85mN/m order of magnitude, the recovery rate of the core permeability is 96%, the anti-swelling rate is 92%, and the anti-emulsifying rate is 90%.
The high-efficiency well flushing fluid provided by the invention can change the wettability of a low-permeability sandstone reservoir from strong hydrophilicity to weak hydrophilicity, eliminate the self-priming capillary force of the reservoir, and reduce the oil-water interfacial tension to 10-4mN/m, preventionThe swelling rate is more than or equal to 94 percent, the milk prevention rate is more than or equal to 98 percent, the core permeability recovery value is more than or equal to 97 percent, and the temperature resistance is more than or equal to 120 ℃.
Claims (5)
1. The efficient well flushing fluid for the low-permeability sandstone oil reservoir is characterized by comprising the following components in percentage by weight:
0.1 to 1.0 percent of waterproof locking agent;
0.5 to 3.0 percent of anti-swelling agent;
5.0 to 10.0 percent of cosolvent;
the balance of water;
the waterproof locking agent is prepared by compounding an anionic surfactant, a cationic surfactant and a nonionic surfactant, wherein the anionic surfactant comprises the following components in molar ratio: cationic surfactant: the nonionic surfactant is (0.4-0.6): (1-1.5): (1.2-1.5);
the anti-swelling agent is polyether diamine.
2. The efficient well-flushing fluid as claimed in claim 1, which is prepared from the following components in percentage by weight:
0.2 to 0.56 percent of waterproof locking agent;
1.5 to 2.8 percent of anti-swelling agent;
6.0 to 8.5 percent of cosolvent;
the balance being water.
3. The high-efficiency well washing fluid as claimed in claim 1, wherein the anionic surfactant is one or a mixture of more of sodium oleate, sodium laurate, sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, the cationic surfactant is one or a mixture of more of dodecyl trimethyl ammonium bromide, hexadecyl trimethyl ammonium bromide, octadecyl trimethyl ammonium chloride and bromo hexadecyl pyridine, and the nonionic surfactant is one or a mixture of more of alkylphenol ethoxylate and fatty alcohol polyoxyethylene ether.
4. The high-efficiency well-flushing fluid as claimed in claim 1, wherein the cosolvent is one or a mixture of methanol, ethanol and propanol.
5. A preparation method of the high-efficiency well flushing fluid for the low-permeability sandstone oil reservoir according to any one of claims 1 to 4, which is characterized in that the well flushing fluid is obtained by directly adding the waterproof locking agent and the cosolvent into water according to the proportion, heating to 45-55 ℃, fully stirring for 1-2 hours, adding the anti-swelling agent after all the treating agents are completely dissolved, and uniformly mixing.
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| CN201710566328.3A CN107286918B (en) | 2017-07-12 | 2017-07-12 | Efficient well flushing fluid for well flushing of low-permeability sandstone oil reservoir |
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| CN201710566328.3A CN107286918B (en) | 2017-07-12 | 2017-07-12 | Efficient well flushing fluid for well flushing of low-permeability sandstone oil reservoir |
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| CN107286918B true CN107286918B (en) | 2020-04-10 |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110317592A (en) * | 2019-07-11 | 2019-10-11 | 河北华北石油港华勘察规划设计有限公司 | A kind of flushing fluid and preparation method thereof |
| CN113088265B (en) * | 2019-12-23 | 2023-04-25 | 中石化南京化工研究院有限公司 | High-temperature-resistant efficient clay stabilizer |
| CN111534290B (en) * | 2020-05-06 | 2022-10-18 | 中国石油天然气集团有限公司 | Water-lock releasing agent for reservoir protection drilling fluid and preparation and use methods thereof |
| CN114316924B (en) * | 2020-10-10 | 2023-09-15 | 中国石油化工股份有限公司 | Waterproof locking agent based on anion-cation pair effect and application thereof |
| CN112430458A (en) * | 2020-12-03 | 2021-03-02 | 成都欣明化工有限公司 | Water-releasing and locking agent for gas well reservoir |
| CN116200180A (en) * | 2021-11-30 | 2023-06-02 | 中国石油天然气股份有限公司 | Low-permeability oil-gas reservoir waterproof locking agent and preparation method thereof |
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