Efficient flowback method of pulverized coal for coal-bed gas well

Abstract

The invention relates to the technical field of coal-bed gas drainage and mining, in particular to an efficient flowback method of pulverized coal using a chemical detergent. The chemical detergent with high foaming quality and high coal-carrying capacity is prepared according to pulverized coal characteristics. An injection device good in simplicity and safety is invented; a safety injection measure and post-injection drainage and mining management method are formulated. Upon injection of the chemical detergent, an additional high-pressure pump is not required; pipeline connection allows thechemical detergent to flow into a casing annulus via self-gravity after tank pressure and casing annulus pressure are balanced. The chemical detergent is injected into the casing annulus; pulverized coal near a wellbore area and a pumping inlet is cleaned; foam generated by the chemical detergent is used to return the pulverized coal to the surface, so that pulverized coal cleaning and pump efficiency improving are achieved. The method herein is simple and feasible, good in safety and high in efficiency. In late coal-bed gas well drainage and mining, intermittent drainage and mining or reinjected water treatment is performed; the pulverized coal can be discharged to the surface with produced water, and pump jamming and other issues are avoided.

Description

technical field [0001] The invention relates to the technical field of coal bed gas extraction, in particular to a method for efficient flowback of pulverized coal in a coal bed gas well. Background technique [0002] During the drainage process of coalbed methane wells, due to various factors such as coal seam geological conditions, fracturing construction and drainage methods, etc., the coal seam and the coal rock structure near the bottom of the well change, resulting in free coal powder and skeleton shedding coal powder in the coal seam migrating with the fluid into the wellbore and pump barrel and carried to the surface. The pulverized coal output from coal seams is one of the important problems encountered in the drainage of coalbed methane wells, and has become the main factor that plagues the commercial development of coalbed methane. The accumulation of pulverized coal at the bottom of the well will not only cause pollution near the well, but also easily cause prob...

AI Technical Summary

Problems solved by technology

[0005] The main purpose of the present invention is to provide a method for efficiently returning pulverized coal using a chemical cleaning agent to solve the problems of low pump efficiency, pump jamming, and poor gas production effect caused by the accumulation of pulverized coal during the drainage process of coalbed methane wells.

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