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A method for controlling water lock damage in coal reservoirs

A technology of water lock damage and control method, which is applied in the direction of earthwork drilling, mining fluid, wellbore/well components, etc., to achieve the effect of reducing surface tension, good surface activity, and reducing contact angle

Active Publication Date: 2017-10-24
HENAN POLYTECHNIC UNIV
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, most of the research results did not involve or pay attention to the problem of reservoir damage caused by reservoir stimulation.

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0022] A method for controlling coal reservoir water lock damage, comprising the steps of:

[0023] 1) Select surface CBM wells for fracturing stimulation;

[0024] 2) Collect reservoir coal samples on site, and test the contact angle of water on the surface of the coal samples indoors;

[0025] 3) Add fast T and chlorine dioxide to the fracturing fluid, select the concentration of fast T according to the contact angle of water on the surface of the coal sample, and select the concentration of chlorine dioxide according to the coal rank of the coal sample; the specific principle is: 0 °<contact angle≤40°, 100ppm<fast T concentration≤500ppm; 40°<contact angle≤90°, 500ppm<fast T concentration≤1000ppm; 90°<contact angle≤180°, 1000ppm<fast T concentration≤2000ppm; For low-rank coal, the concentration of chlorine dioxide is 500-1000ppm; for medium-rank coal, the concentration of chlorine dioxide is 1000-2500ppm but not including 1000ppm; for high-rank coal, the concentration of ch...

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Abstract

The invention relates to a method for controlling water lock damage in coal reservoirs, which comprises the following steps: 1) selecting ground coalbed gas wells for fracturing reconstruction; 2) collecting reservoir coal samples on site, and testing the contact angle of water on the surface of the coal samples indoors ;3) Add fast T and chlorine dioxide to the fracturing fluid, select the concentration of fast T according to the contact angle of water on the surface of the coal sample, and select the concentration of fast T according to the coal rank of the coal sample (that is, the degree of metamorphism of the coal sample). Chlorine concentration; 4) The fracturing fluid after adding fast T and chlorine dioxide and stirring evenly can be used as pre-fluid or sand-carrying fluid for joint hydraulic fracturing with inactive water fracturing fluid, pre-fluid and sand-carrying fluid 20-30 cubic meters of active water fracturing fluid needs to be pumped in between the hydraulic fracturing fluids for isolation; 5) The flowback of the fracturing fluid can be started at least 3 hours after the hydraulic fracturing is completed. The method reduces the surface tension and capillary resistance of the coalbed methane reservoir, reduces the water lock damage of the reservoir, and is beneficial to protect the coalbed methane reservoir and improve the recovery rate of the coalbed methane.

Description

technical field [0001] The invention belongs to the technical field of coalbed methane exploration and development coalbed methane well reservoir reconstruction technology, and in particular relates to a method for controlling coal reservoir water lock damage. Background technique [0002] The coal reservoir conditions of low permeability, low impending storage pressure ratio, and low gas saturation in China are not conducive to the commercial development of coalbed methane. The methane-friendly ability and other aspects of coal reservoirs have been studied, and certain effects have been achieved in the transformation of coal reservoirs. However, most of the research results did not involve or pay attention to the reservoir damage caused by reservoir stimulation. [0003] Water lock effect is one of the main factors causing damage to coalbed methane reservoirs. The coalbed methane reservoir is a complex porous medium. After the foreign fluid invades, the gas in the fractur...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/26
Inventor 苏现波宋金星苏黎楠郭红玉李贤忠司青
Owner HENAN POLYTECHNIC UNIV
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