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Method for improving water absorption profile by combining profile control and acidification

A technology of water absorption profile and joint cropping, which is applied in chemical instruments and methods, earthwork drilling, drilling composition, etc., can solve the problem of inability to effectively displace low-permeability matrix oil layers, etc., and achieve the effect of improving water absorption profile.

Active Publication Date: 2019-10-15
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the tight matrix of low-permeability reservoirs, water injection wells often cannot effectively displace low-permeability matrix oil layers after profile control and plugging of high-permeability zones such as large pores and micro-fractures
Therefore, there is a contradiction between high-permeability plugging and low-permeability displacement

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] The invention provides a method for improving the water absorption profile by combining profile control and acidification. Firstly, a flexible gel particle slug is injected into the perforation section of the oil layer for profile control and plugging of the high-permeability section; and then injected into the perforation section of the oil layer The retarded acid system is used to acidify the low-permeability interval; the injection volume ratio of the flexible gel particle slug to the retarded acid system is (400-600): (15-20).

[0020] In this method, flexible gel particles are used for profile control to plug the large pores of the dominant water flow in the oil layer, so as to realize the liquid flow diversion of the subsequent injection medium. The respective advantages of gel particles blocking the large pores and slow acid acidifying the low-permeability layer can be combined to improve the water absorption profile.

Embodiment 2

[0022] On the basis of the above examples, further, the flexible gel particle slug comprises the following components by mass ratio: 0.3%-0.5% flexible gel particle, 0.05%-0.1% polyacrylamide solution, and The amount is water. The preparation method of the flexible gel particle slug is to dissolve the polyacrylamide solution of the formulated amount in water first, then add the flexible gel particle of the formulated amount, stir and mix evenly to make the flexible gel particle slug base liquid , the flexible gel slug base fluid is injected into the predetermined position of the perforation section to form a flexible gel particle slug.

[0023] Further, the molecular weight of the polyacrylamide is 13 million to 18 million, and the degree of hydrolysis is 20%-28%.

[0024] The flexible gel particles include the following components by mass percentage: 3%-6% acrylamide, 0.03%-0.06% N, N-methylenebisacrylamide, 0.01%-0.03% ammonium persulfate, 0.02% %-0.04% sodium sulfite, 2%-...

Embodiment 3

[0027] On the basis of the above examples, further, the retarded acid system, by mass percentage, includes the following components: 15%-17% hydrochloric acid, 9%-12% hydrofluoric acid, 32%-35% phosphoric acid Dihydrogen salt, 1%-3% acetic acid, 3%-5% ammonium fluoride, 2%-4% iron ion stabilizer, 1.2%-2.4% corrosion inhibitor, 0.3%-0.5% drainage aid, the balance for water.

[0028] The iron ion stabilizer is formed by mixing citric acid and acetic acid in a mass ratio of 6:4, the corrosion inhibitor is benzyl quinoline chloride, and the drainage aid is alkylsulfonate salt.

[0029] The rock dissolution rate of the retarded acid system is 15%-20% after the acid-rock reaction time of 4 hours, and the average corrosion rate of the N80 steel sheet is 0.81-0.95 g / ㎡•h.

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PUM

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Abstract

The invention provides a method for improving a water absorption profile by combining profile control and acidification, the method comprises the following steps: firstly, injecting a flexible gel particle slug into an oil layer perforation section for profile control and plugging of dominant large pore channels, and then injecting a retarded acid into the oil layer perforation section for acidizing a low-permeability layer section. Flexible gel particles are used for profile control and plugging of the dominant water flow large pore channels of an oil layer so as to realize the liquid flow diversion of a subsequent injection medium. On this basis, the injected retarded acid acidizes a low-permeability layer is not affected or relatively weakly affected by water drive, the respective advantages of the flexible gel particles for plugging the large pore channels and the retarded acid for acidizing the low-permeability layer are fully brought into play to improve the water absorption profile in combination. The method has the advantages the acid liquor is prevented from reacting with a water layer or the dominant water flow channels and fully reacts in the low-permeability layer, theineffective action of the acid is reduced, and the water absorption profile is effectively improved.

Description

technical field [0001] The invention relates to the technical field of petroleum exploitation, in particular to a method for improving a water absorption profile by combining profile control and acidification. Background technique [0002] Low-permeability reservoirs have large reserves, low abundance, tight reservoirs but developed micro-fractures. Water injection is still the main means of effective development of low-permeability oilfields. In the process of water flooding development, due to the heterogeneity of the reservoir or the existence of micro-cracks, the long-term development forms a dominant water flow channel, which makes the injected water easy to advance quickly, forming a situation of "water channeling in high permeability layers and water flooding in low permeability layers". , resulting in a rapid rise in water cut in the oil well, a rapid decline in production, and even water flooding. In response to the above problems, the current common practice is to...

Claims

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Application Information

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IPC IPC(8): C09K8/508C09K8/516C09K8/74E21B33/13E21B43/16
CPCC09K8/5086C09K8/516C09K8/74E21B33/13E21B43/16
Inventor 吴天江杨海恩何治武郑力军宋昭杰朱家杰曹荣荣任建科张荣
Owner PETROCHINA CO LTD
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