A well layout method for surface pumping and drainage of coalbed methane

Abstract

The invention discloses a well distributing method for pumping and draining coal bed gas on the ground and belongs to the field of development of the coal bed gas. On the basis of the theory of one potential energy and three fields, the gravitational potential energy of water in the coal bed is utilized, and according to the distribution characteristics of a gravity field, a ground stress field and a pressure field in the coal bed and by combination with the occurrence of coal reservoirs and the characteristics of the drilling process of a multi-branch horizontal well, a U-shaped horizontal well and a vertical well (cluster well), different well types are selected for well distributing for pumping and draining the coal bed gas on the ground. The well distributing method disclosed by the invention has the advantages that the effect of optimized configuration of the well types in well distributing for pumping and draining the coal bed gas on the ground with the geologic structure condition and the characteristics of the coal-bed-gas drainage and production is effectively realized, the unique energy 'gravitational potential energy' of water in the coal bed in the drainage process is fully utilized, the well is built according to the potential energy, the well types of pumping and draining wells on the ground are reasonably distributed according to the distribution characteristics of the gravity field, the ground stress field and the pressure field and by combination with the structure conditions of different coal reservoirs, so that the water-draining and pressure-reducing efficiency is effectively improved and the benefit to improving the development effect of the coal bed gas is achieved.

Description

technical field [0001] The invention relates to a method for arranging wells for extracting coalbed methane from the ground, and belongs to the field of coalbed methane exploitation. Background technique [0002] The rationality of well location deployment and well type selection directly determines the cost of coalbed methane drilling and the effectiveness of development work. Coalbed methane is a kind of adsorbed gas, which belongs to unconventional natural gas. In the drainage process, there is no natural energy such as elastic drive, solution gas drive, hydraulic drive, air pressure drive and artificial supplementary energy in conventional natural gas reservoirs. The only energy that promotes the desorption of coalbed methane is the water in the coal reservoir under its own gravity. After being discharged under the action, the pressure of the coal reservoir is reduced, resulting in the desorption of the coal seam. The so-called coal seam desorption refers to the proces...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for arranging wells for surface extraction of coalbed methane, in order to solve the problem of optimal configuration of well type, geological structure conditions, and coalbed methane extraction characteristics in the process of surface extraction of coalbed methane, and make full use of the coalbed methane The only natural energy "gravity potential energy" in the process of water discharge, the well is built according to the "potential", according to the distribution characteristics of the gravity field, in-situ stress field, and pressure field, combined with the occurrence of coal seams and multi-branch horizontal wells, U-shaped horizontal wells, Drilling technology characteristics of vertical wells (cluster wells), rational selection of different well types to improve development results

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