Coal seam in-situ pyrolysis method

Abstract

The invention provides a coal seam in-situ pyrolysis method. The coal seam in-situ pyrolysis method comprises the steps that a water injection well / extraction well which takes an ignition well as thecenter and is distributed in a regular polygon state is arranged for well drilling; and oxygen-enriched air is injected into the ignition well, ignition is conducted, the ignition well with the higherfluid pressure serves as the extraction well to conduct pyrolysis product extraction operation according to the fluid pressure under the water injection well / extraction well close to the ignition well. According to the coal seam in-situ pyrolysis method, the combustion direction of the coal seam in the combustion well is controlled through the water injection amount of the water injection well, the ignition well and the water injection well are distributed in a regular polygon shape, the water injection well and the extraction well can be switched in real time, directional perforation is conducted on the coal seam in the water injection well / extraction well, the combustion direction can be effectively controlled, injection of external heat-carrying fluid is not needed, therefore efficientconversion of underground coal resources and extraction of oil and gas resources can be realized, and the method has the advantages of simplicity and feasibility.

Description

technical field [0001] The invention belongs to the technical field of producing oil and gas from oil shale and coal resources, and in particular relates to an in-situ pyrolysis method for coal seams. Background technique [0002] In recent years, the underground in-situ pyrolysis technology of oil shale and coal has attracted more and more attention. This method generally includes two ways of thinking. [0003] One method is collectively referred to as the external heat method, and the main patents published so far include "Method for Oil and Gas Exploitation of Convective Heating Oil Shale (200510012473.4)", "Method for Oil and Gas Exploitation of Oil Shale by Convective Heating of High-temperature Hydrocarbon Gas (200710139353.X) ", specifically, through the existing drilling technology and fracturing methods, artificial fracture networks are created in the rock formation, and then high-temperature heat carriers such as superheated steam or superheated hydrocarbon gas are...

AI Technical Summary

Problems solved by technology

[0005] The main problem faced by the technical solution of the external heat method is how to inject external heat into the underground coal seam. In the current solution, using superheated steam or hydrocarbon gas as the heat carrier to inject the coal seam often has a large heat loss, and the wellbore insulation performance is extremely high.

However, the biggest difficulty faced by the technical scheme of internal heat method lies in the problem of controlling the direction of coal underground combustion. At present, there is no very effective solution. Generally, the direction of combustion is controlled based on the direction of drilling and gas injection, but the implementation effect is not ideal.

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