Program and method for controlling pressure of nitrogen injection production increase coal bed gas

Abstract

The invention discloses a program and method for controlling the pressure of nitrogen injection production increase coal bed gas. The method comprises the steps: enabling the response of a coal bed gas storage layer to the nitrogen injection pressure and rate of a nitrogen injection well and the changes of well mouth pressure, gas output and nitrogen volume percentage composition of a production well to be fed back to the nitrogen injection well, and adjusting the nitrogen injection pressure and rate; holding the pressure of the coal bed gas storage layer in necessity, and even carrying out conversion and employing a low-pressure oscillation pressurization mode; converting the coal bed gas storage layer in necessity and employing a high-pressure oscillation pressurization mode. Only if the coal bed has enough gas, are the program and method suitable for any coal bed. The method provided by the invention guarantees that the injected nitrogen enters into the coal bed, passes through all coal bed between the nitrogen injection well and the production well, enables the nitrogen to enter into miniature gaps of the coal bed, prompts adsorbed-state coal bed gas to be desorbed, drives the desorbed free-state coal bed gas to arrive at the production well, and achieves the purpose of coal bed gas yield increase.

Description

technical field [0001] The invention relates to a pressure control program and method for increasing production of coal bed methane by injecting nitrogen. Specifically, the present invention relates to a method of injecting nitrogen into a coal seam from one or more wells connected to the coal seam (hereinafter referred to as "nitrogen injection well") to promote the desorption of hydrocarbon gases, and from multiple wells connected to the coal seam (hereinafter referred to as "nitrogen injection well") The pressure control procedures and methods used when collecting the produced hydrocarbon gas and the mixed gas of hydrocarbon gas and nitrogen to increase the production of coalbed methane. Background technique [0002] Coalbed methane is combustible hydrocarbon gas in coal seams, also known as gas, and its main component is methane. Coal bed methane is not only a clean energy source of natural gas, but also the cause of gas outburst and explosion in coal mines. According ...

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Problems solved by technology

The patented method of Puri and Stein has not been used by the world's coalbed methane industry. One of the reasons is that, in fact, the patented method's requirement for nitrogen injection pressure is only suitable for high-quality coalbed methane reservoirs with high permeability, and for most coalbed methane Reservoir is incorrect and cannot be implemented

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