Deep coal bed gas abandoned well and long-stop well recovery method

Abstract

The invention discloses a deep coalbed methane abandoned well and long-stop well recovery method, and belongs to the technical field of coalbed methane development. A multi-branch horizontal well and a main horizontal well section are constructed in a well area, the branch horizontal well section drills along a midpoint of a connecting line of target points of an adjacent abandoned well and a long-stop well in a coal reservoir, a screen pipe is hung in a main horizontal well hole for well completion, and a branch horizontal well hole is subjected to open hole well completion. In the water injection stage, water is injected into the multi-branch horizontal well to improve the energy of a coal reservoir, and inter-well rapid migration after CO2 injection is inhibited; in the CO2 injection stage before recovery, CH4 is made to flow towards the abandoned well and the long-stop well by means of the replacement and displacement effect of CO2 on CH4; and in the subsequent CO2 injection stage of production recovery, the well bottom flowing pressure of the abandoned well and the long-stop well is reduced through drainage, and the daily gas production rate is gradually increased. According to the method, high-permeability channels are plugged through water injection, CH4 is replaced and displaced through CO2 injection, the deep coal-bed gas waste well and the long-stop well generate gas again, the service life of the coal-bed gas well can be prolonged, deep coal-bed gas storage of CO2 can be achieved, and remarkable economic and environmental benefits can be generated.

Description

technical field [0001] The invention relates to an abandoned coalbed methane well and a method for resuming production from long-stopped wells, in particular to a method for reproducing production from deep-seated coalbed methane abandoned wells and long-stopped wells with low recovery rate of coalbed methane resources within the well control range of coalbed methane wells Methods. Background technique [0002] The coalbed group development area of ​​the Upper Permian in Southwest my country and the deep coalbed methane in the Carboniferous Permian coal-bearing basin in North China are rich in resources and have great potential for resource development. Due to the generally high degree of coal metamorphism in the area, and the influence of factors such as high in-situ stress on the deep coal reservoir, the permeability of the deep coal reservoir is extremely low, which makes it difficult to expand the reservoir pressure reduction funnel when using the traditional drainage ...

AI Technical Summary

Problems solved by technology

Due to the generally high degree of coal metamorphism in the area, and the superimposition of factors such as high in-situ stress on deep coal reservoirs, the permeability of deep coal reservoirs is extremely low, which makes it difficult to expand the pressure drop funnel of the reservoir when the traditional drainage and depressurization mining method is adopted. The service life of coalbed methane wells is short, the recovery rate of coalbed methane resources within the well control range is low, and the economic benefits of coalbed methane development are poor

In order to comprehensively promote the development of deep coalbed methane in North my country, Southwest China, and Northwest China, it is necessary to solve the problems of short service life of deep coalbed methane wells and low recovery rate of coalbed methane resources within the control range of the well group under the traditional coalbed methane mining method. Improve the economic, social and environmental benefits of deep coalbed methane development by extending the service life of deep coalbed methane wells

[0003] Judging from the current situation, some provinces already have a large number of abandoned CBM wells and long-term shutdown wells that have been abandoned due to poor gas production effects and have been shut down for a long time. The total amount of coalbed methane resources produced is small, the recovery rate of coalbed methane resources is low, and there is still a large potential for coalbed methane resource exploitation

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