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Method for improving CO2 flooding effect of low-permeability reservoir

A low-permeability, oil-reservoir technology, applied in chemical instruments and methods, earthwork drilling and production, wellbore/well components, etc., can solve problems such as fingering, easy gas channeling and viscosity, etc., to prolong gas breakthrough time, suppress Gas channeling, good expansibility effect

Inactive Publication Date: 2020-01-03
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The object of the invention is to provide a method for improving the CO 2 The purpose of this method is to solve the problems of gas channeling and viscous fingering that are prone to occur in the prior art

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] A method for improving CO in low-permeability reservoirs 2 The method of driving effect includes the following steps:

[0023] The first step is to inject the gel particle suspension, inject the gel particle suspension into the oil layer before the slug, and the injection volume accounts for 4%~6% of the total daily injection volume;

[0024] The second step, alternate injection, alternately injects polymer microsphere solution slugs and CO into the oil layer. 2 For gas drive slugs, the injection volume accounts for 94%~96% of the total daily injection volume.

[0025] The total daily injection volume is 1.0 times the daily water injection volume of the target gas injection well.

[0026] In the first step, the gel particle suspension contains, by mass percentage, 0.05%-0.10% polyacrylamide and 0.5%-1.0% gel particles, and the rest is water.

[0027] The polyacrylamide is an anionic partially hydrolyzed polyacrylamide, with a number average molecular weight of 18 mil...

Embodiment 2

[0040]Inject pre-slug gel particle suspension 300m 3 , with an injection velocity of 1.5m 3 / h. The gel particle suspension contains, by mass percentage, 0.08% polyacrylamide, 0.9% gel particles, and the rest is water. The polyacrylamide is an anionic partially hydrolyzed polyacrylamide with a number average molecular weight of 18 million, a degree of hydrolysis of 22%, and a solid content of 91%. The gel particles are based on 6% of acrylamide monomer, 7% of sodium montmorillonite, and 0.03% of N,N'-methylenebisacrylamide as a cross-linking agent. Ammonium sulfate 0.19% is the initiator, sodium chloride 0.1%, ammonium chloride 0.9% is the pH regulator, and the rest is water. The colloid formed by copolymerization is mechanically cut and granulated to obtain gel particles with a particle size of 3 mm. . The volume expansion factor is 3.

[0041] Alternately inject polymer microsphere solution slugs and CO 2 Gas drive slug total 5000m 3 , polymer microsphere solution and...

Embodiment 3

[0043] Inject pre-slug gel particle suspension 320m 3 , the injection speed is 2.0m 3 / h. The gel particle suspension contains, by mass percentage, 0.06% polyacrylamide, 0.8% gel particles, and the rest is water. The polyacrylamide is an anionic partially hydrolyzed polyacrylamide with a number average molecular weight of 18 million, a degree of hydrolysis of 22%, and a solid content of 91%. The gel particles are based on 7% of acrylamide monomer, 8% of sodium montmorillonite, and 0.035% of N,N'-methylenebisacrylamide as a cross-linking agent. Ammonium sulfate 0.18% is the initiator, sodium chloride 0.11%, ammonium chloride 0.8% is the pH regulator, and the rest is water. The colloid formed by copolymerization is mechanically cut and granulated to obtain gel particles with a particle size of 4 mm. . The volume expansion factor is 4.

[0044] Alternately inject polymer microsphere solution slugs and CO 2 Gas drive slug total 5600m 3 , polymer microsphere solution and liq...

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Abstract

The invention discloses a method for improving the CO2 flooding effect of a low-permeability reservoir. The method for improving the CO2 flooding effect of the low-permeability reservoir comprises thefollowing steps: step 1, a gel particle suspension is injected, gel particle suspension pre-slugs are injected into an oil layer, and the injection amount occupies 4%-6% of the percentage by volume,of a daily total injection amount; and step 2, alternating injection is carried out, polymeric microsphere solution slugs and CO2 flooding slugs are injected into the oil layer in an alternating manner, and the injection amount occupies 94%-96% of the percentage by volume, of the daily total injection amount. The gel particle suspension comprises, in percentage by mass, 0.05%-0.10% of polyacrylamide, 0.5%-1.0% of gel particles and the balance water; and a polymeric microsphere solution comprises, in percentage by mass, 0.1%-0.2% of polymeric microspheres and the balance water. In a polymeric microsphere system, a 2-acrylamide-2-methylpropane sulfonic acid AMPS monomer is introduced, so that the salt-resistant and acid-resistant performance is optimized, the utilization rate of subsequently-injected CO2 is increased, the swept volume of the CO2 is increased, and the CO2 flooding effect is improved.

Description

technical field [0001] The invention belongs to the technical field of profile control and channeling sealing in oil and gas field exploitation, and in particular relates to a CO 2 The method of drive effect. Background technique [0002] Reservoirs have entered a medium-to-high water cut period, and the task of controlling water and increasing oil production is arduous. At present, enhanced oil recovery technologies include polymer surface binary flooding, microbial flooding, air flooding and other technologies, but due to the constraints of reservoir geological conditions, safety and other factors, the promotion and large-scale application of oilfields have not been realized. Therefore, there is an urgent need to explore enhanced oil recovery technologies suitable for low-permeability reservoirs. In recent years, CO 2 The technology of enhanced oil and gas recovery by flooding has been widely concerned and applied due to its dual advantages of economy and environmental ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B43/16E21B43/22C09K8/588C09K8/594
CPCC09K8/588C09K8/594E21B43/16E21B43/164
Inventor 薛芳芳杨海恩何治武易萍贾玉琴马波周广卿贺晨刚刘明
Owner PETROCHINA CO LTD
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