Design method for coal reservoir transformation

Abstract

The embodiment of the invention discloses a design method for coal reservoir transformation, and belongs to the field of coalbed methane exploration. The design method comprises the following steps: acquiring the thickness, the effective porosity, the phase change transformation radius and the phase change transformation temperature of a coal reservoir, acquiring a shaft heat loss efficiency of an injection well, confirming a phase change fluid amount and a partitioning fluid amount according to the phase change transformation radius and the effective porosity of the coal reservoir, confirming an injection delivery capacity and the highest pressure of the opening of the injection well when fluid is injected into the coal reservoir according to fracture pressure of the coal reservoir, confirming a cold amount for phase change transformation coal reservoir according to the phase change fluid amount, the specific heat capacity of a pore medium in the coal reservoir, and the density and the phase change transformation temperature of the pore medium in the coal reservoir, confirming a refrigerant amount and a cold source amount according to the shaft heat loss efficiency, the specific heat capacity of a refrigerant liquid and the temperature of the refrigerant liquid after heat exchange with the ground, and transforming the coal reservoir according to phase change of the phase change fluid. By adoption of the design method, the coal reservoir transformation efficiency can be improved.

Description

technical field [0001] The invention relates to the field of coal bed gas exploitation, in particular to a design method for transforming coal reservoirs. Background technique [0002] Due to the special structure of coal reservoirs, a large amount of coalbed methane (such as gas) is often adsorbed in coal reservoirs, and the permeability of coal reservoirs is usually low, which makes the production capacity of coalbed methane low. In order to increase the production capacity of coalbed methane , it is necessary to transform the coal reservoir to increase the permeability of the coal reservoir. [0003] Usually, the main way to increase the production of coalbed methane is to use hydraulic fracturing to transform the coal reservoir. Specifically, through the transmission of liquid to the pressure, a high-pressure pump is used on the surface to inject pressure into the pressure well with a displacement greater than the absorption capacity of the formation. Fracture fluid, be...

AI Technical Summary

Problems solved by technology

[0005] In the above-mentioned coal reservoir reconstruction method, when the coal reservoir is reconstructed with fracturing fluid, due to the characteristics of low Young's modulus and high Poisson's ratio of the coal reservoir, large displacement liquid and proppant are scoured at high speed during hydraulic fracturing. Coal reservoirs will produce a large amount of coal powder, and the output and migration of coal powder will block the seepage channel, thus making the efficiency of reservoir reconstruction low

Images