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Method for surface modification and transmission increase of coal reservoirs by using chlorine dioxide

A chlorine dioxide and surface modification technology, which is used in earth-moving drilling, gas discharge, and production of fluids, etc., can solve the problems of low gas saturation, low gas production in a single well, and unsatisfactory effects, so as to improve the gas content. Saturation, improving extraction efficiency, increasing daily gas production and recovery

Inactive Publication Date: 2014-04-16
HENAN POLYTECHNIC UNIV
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Problems solved by technology

The reason is that China's coalbed methane has the characteristics of "three lows", that is, low permeability, low gas saturation and low immediate-storage ratio. Although the reservoir stimulation technology adopted is similar to that of foreign countries, the effect is not satisfactory , mainly due to low single well gas production, short stable production period, and low recovery

Method used

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Effect test

Embodiment Construction

[0012] The surface modification and anti-permeability methods of chlorine dioxide on coal reservoirs include the following steps in turn: (1) Select the proportioning concentration of chlorine dioxide according to the coal rank and laboratory tests; (2) Select the reservoir for hydraulic fracturing (3) In the process of hydraulic fracturing, chlorine dioxide with a selected concentration is pumped in stages, and the pumping amount in the pre-fluid stage is not less than 70%; ( 4) Shut down the well for more than 3 hours and start to flow back the fracturing fluid; (5) Effect test, the main indicators include the critical desorption pressure, daily gas production and ultimate recovery of the coalbed methane well, or the drainage volume of the downhole drilling.

[0013] The above step (1) The level of coal rank determines the concentration of chlorine dioxide. The basic principle is: the concentration of chlorine dioxide in weakly sticky coal and below coal rank is 500~1000ppm, ...

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Abstract

The invention relates to a method for surface modification and transmission increase of coal reservoirs by using chlorine dioxide. The method sequentially comprises the following steps of: (1) selecting the proportioning concentration of the chlorine dioxide according to a coal step and a laboratory experiment; (2) selecting a ground coalbed methane well or an underground drill hole for hydraulic fracturing reservoir modification; (3) pumping chlorine dioxide with selected concentration by stages in the hydraulic fracturing process, wherein the pumping amount in the prepad fluid stage is not less than 70 percent; (4) closing the well for more than 3 hours, and starting to return discharge of a fracturing fluid; and (5) inspecting effects, wherein main indexes comprise critical desorption pressure, daily gas yield and ultimate recovery ratio of the coalbed methane wells or the pumping amount of the underground drill hole. By the method, the daily gas yield and the recovery rate of a single well can be improved, the underground drilling and extraction capability is improved, the extraction efficiency is improved, and the pumping time is shortened.

Description

technical field [0001] The invention relates to a method for surface modification and anti-permeability of coal reservoirs by chlorine dioxide. Background technique [0002] The development of coalbed methane can obtain efficient and clean energy, reduce the cost of coal mine gas treatment, and also reduce greenhouse gas emissions. China has drilled more than 5,000 wells in the eastern margin of the Ordos Basin, Qinshui Basin, Yangquan, Fuxin, Tiefa, Liupanshui in Guizhou, Jiaozuo and Anyang in Henan (as of the end of 2009), and only some areas have achieved commercial development. The reason is that China's coalbed methane has the characteristics of "three lows", that is, low permeability, low gas saturation and low immediate-storage ratio. Although the reservoir stimulation technology adopted is similar to that of foreign countries, the effect is not satisfactory , mainly due to low single well gas production, short stable production period, and low recovery factor. Con...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/26E21F7/00
Inventor 苏现波郭红玉夏大平刘晓宋金星倪小明韩颖蔺海晓陈俊辉
Owner HENAN POLYTECHNIC UNIV
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