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

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 penetration enhancement of coal reservoirs by chlorine dioxide. Background technique [0002] The development of coal-bed 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, Guizhou Liupanshui, Henan Jiaozuo and Anyang (as of the end of 2009), and only some areas have achieved commercial development. The reason is that the occurrence of CBM in China has the characteristics of "three lows", that is, low permeability, low gas saturation and low temporary reserve ratio. Although the technology adopted for reservoir improvement and stimulation is similar to that of foreign countries, the effect is not satisfactory. , Mainly due to the low gas production of a single well, short stable production perio...

AI Technical Summary

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