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A water-based drilling fluid for protecting oil and gas reservoirs with high temperature and calcium resistance and its application

A technology for water-based drilling fluids and oil and gas reservoirs, applied in the field of water-based drilling fluids, can solve the problems of large consumption of treatment agents, scrapped wellbore, polluted reservoirs, etc.

Inactive Publication Date: 2021-05-28
CNPC DRILLING RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Anti-ultra-high temperature and high calcium (CaCl 2 ≥1%) drilling fluid is the key to the success of drilling in deep salt-gypsum formations, but the existing drilling fluids are difficult to meet the requirements of ultra-high temperature resistance and reservoir protection under the condition of large-section salt-gypsum formations, and drilling projects are faced with a series of failures due to high temperature of drilling fluids Major technical problems such as borehole wall collapse, pipe sticking, blowout and reservoir pollution
During deep drilling, high-temperature failure of the drilling fluid makes it difficult to carry rock and suspend heavy materials, and it is difficult to effectively support the well wall, which may easily lead to major safety accidents such as well collapse, drill sticking, and blowout, and even lead to the scrapping of the wellbore
At present, water-based drilling fluids are used to drill ultra-high temperature wells in salt-bearing gypsum formations. The main method is to increase the amount of chemical treatment agents to maintain the performance of the drilling fluid. Large pollution, slow drilling speed, long drilling cycle, high production safety and public safety risks, seriously affect the quality, speed and efficiency of drilling, and even affect the realization of geological goals

Method used

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  • A water-based drilling fluid for protecting oil and gas reservoirs with high temperature and calcium resistance and its application
  • A water-based drilling fluid for protecting oil and gas reservoirs with high temperature and calcium resistance and its application
  • A water-based drilling fluid for protecting oil and gas reservoirs with high temperature and calcium resistance and its application

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Experimental program
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Effect test

preparation example Construction

[0026] In the water-based drilling fluid of the present invention, the preparation method of the above-mentioned fluid loss control agent comprises: in the presence of sodium lauryl sulfate and 2,2-azobis(2-methylpropylimidium) dihydrochloride, The monomer M1 shown in formula (4), the monomer M2 shown in formula (5), and the monomer M3 shown in formula (6) are polymerized in water as a solvent,

[0027]

[0028] Among them, R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 9 , R 10 and R 11 each independently hydrogen, C 1 -C 4 Alkyl or C 1 -C 4 Alkoxy, preferably hydrogen, methyl, ethyl, methoxy or ethoxy; R 8 from C 1-C 4 The alkylene group is preferably methylene or ethylene.

[0029] In the above preparation method of fluid loss control agent, the mass ratio of the monomer M1, the monomer M2 and the monomer M3 is (0.1-0.2):1:(0.05-0.1), preferably (0.1 -0.15):1:(0.05-0.075), more preferably (0.12-0.15):1:(0.055-0.07).

[0030] In the above-mentioned preparat...

preparation example 1

[0066] Adjust the temperature of the water bath to 80°C, dissolve sodium lauryl sulfate in distilled water and pour it into a three-neck flask, stir with a magnetic force at an appropriate speed for 15 minutes; add 100g of distilled water to a 100ml beaker, and add formula (4-1) The monomer M1 shown, the monomer M2 shown in the formula (5-1), and the monomer M3 shown in the formula (6-1). After it is completely dissolved, add it to the three-necked flask, and stir for 30 minutes under the protection of nitrogen; dissolve 2,2-azobis(2-methylpropylimidium) dihydrochloride in distilled water, and then add it dropwise to the three-necked flask Among them, the mass ratio of monomers M1, M2 and M3 is 0.15:1:0.075, monomer M2, sodium lauryl sulfate and 2,2-azobis(2-methylpropylimidium) dihydrochloride The mass ratio is 200:0.5:0.4. After reacting for 5 hours, copolymer A1 was obtained with a number average molecular weight of 42,000.

[0067]

preparation example 2

[0069] Adjust the temperature of the water bath to 80°C, dissolve sodium lauryl sulfate in distilled water and pour it into a three-neck flask, stir with a magnetic force at an appropriate speed for 15 minutes; add 100g of distilled water to a 100ml beaker, and add formula (4-2) The monomer M1 shown, the monomer M2 shown in the formula (5-1), and the monomer M3 shown in the formula (6-1). After it is completely dissolved, add it to the three-necked flask, and stir for 30 minutes under the protection of nitrogen; dissolve 2,2-azobis(2-methylpropylimidium) dihydrochloride in distilled water, and then add it dropwise to the three-necked flask Among them, the mass ratio of monomers M1, M2 and M3 is 0.1:1:0.05, monomer M2, sodium lauryl sulfate and 2,2-azobis(2-methylpropylimidium) dihydrochloride The mass ratio is 100:0.3:0.2. Copolymer A2 was obtained after reacting for 5 hours, and its number average molecular weight was 20,000.

[0070]

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Abstract

The invention relates to the technical field of petroleum drilling, and discloses a water-based drilling fluid for protecting oil and gas reservoirs with high temperature and calcium resistance and an application thereof. The water-based drilling fluid contains a fluid loss control agent and a plugging agent, and the fluid loss control agent Be the copolymer containing the structural unit shown in formula (1), the structural unit shown in formula (2) and the structural unit shown in formula (3), wherein, the structural unit shown in formula (1), formula (2 The mass ratio of the structural unit shown in ) to the structural unit shown in formula (3) is (0.1-0.2):1:(0.05-0.1), and the number average molecular weight of the copolymer is 10,000 to 100,000. The blocking agent is acrylamide-diallyldimethylammonium chloride copolymer modified graphene. When the drilling fluid described in the present invention is applied to high-temperature deep well drilling, it can exhibit better fluid loss control performance, plugging performance, temperature resistance, collapse prevention performance and reservoir protection performance.

Description

technical field [0001] The invention relates to the technical field of drilling, in particular to a high temperature and calcium resistant water-based drilling fluid for protecting oil and gas reservoirs and its application. Background technique [0002] According to the results of the second national oil and gas resource evaluation, the total oil resources in my country are 94 billion tons, and the conventional natural gas resources are 38 trillion m 3 , the remaining oil and gas resources are mainly distributed in deep layers. The depth of deep reservoirs in my country is generally more than 5000m, and the deepest is nearly 9000m at present, the bottom hole temperature is 180-260°C, and there are large sections of salt-gypsum layers in most areas. At present, oilfields such as Daqing, South China Sea, Jilin, Xinjiang, Tarim, and Dagang are all implementing ultra-deep well drilling. Anti-ultra-high temperature and high calcium (CaCl 2 ≥1%) drilling fluid is the key to th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F220/58C08F212/08C08F220/18C09K8/035C09K8/24
CPCC08F220/58C09K8/035C09K8/24C09K8/426C09K8/467C08F220/585C08F212/08C08F220/1804C08F212/12B82Y30/00C09K8/5045C09K8/508C09K8/516C09K2208/12C01B32/184C01B32/194C01B32/198B82Y40/00C08F226/04C08F2800/20C08F2810/00C09K2208/10E21B21/003E21B21/062
Inventor 杨宇平刘敬平常敏李龙王金宏孙金声
Owner CNPC DRILLING RES INST