Coal reservoir present geostress prediction method

Abstract

The invention relates to a coal reservoir present geostress prediction method, which is characterized in that on the coal rock parameter experiment test and logging curve calculation basis, the quantitative relationship between the static parameter and the dynamic parameter is built; the rock mechanical characteristics of low Young modulus, high poisson ratio, low intensity, easy damage and the like of the coal rock are considered; unknown parameters in the present geostress module based on a Maxwell cola reservoir are obtained through inversion; the coal reservoir geostress profile based on the logging curve is built; the goal of predicting the coal reservoir present geostress is achieved. The targeted performance is high; the coal reservoir present geostress can be accurately predicted;the foundation is laid for the effective exploration and development of coal bed gas; the risk and the cost are reduced; the method can be widely applied to the technical field of coal bed gas exploration and development.

Description

technical field [0001] The invention relates to the technical field of coalbed methane exploration and development, in particular to a method for predicting the current in-situ stress of coal reservoirs. Background technique [0002] With the deepening of oil and gas exploration and development, unconventional oil and gas such as coalbed methane, shale gas and tight oil and gas have gradually shown great potential. Coalbed methane is a kind of unconventional natural gas that mainly occurs in coal seams and surrounding rocks in the state of adsorption, and its global resources are about 256.3×10 12 m 3 , the geological resources of CBM within 2000m buried depth in China are 36.8×10 12 m 3 , of which the recoverable resources are 10.9×10 12 m 3 . [0003] The current state of in-situ stress has an important impact on the exploration and development of coalbed methane: (1) The permeability of coalbeds is one of the key factors restricting the development of coalbed methan...

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Problems solved by technology

(4) Today's in-situ stress affects the adsorption, desorption, diffusion and seepage of coalbed methane, thereby affecting the output of coalbed methane

At present, for the prediction of the current in-situ stress of the coal seam, the existing technologies mainly include two types: (1) The research on the prediction of the in-situ stress of the conventional sand-mudstone reservoir has been relatively in-depth, and the prediction of the current in-situ stress of the coal seam still uses the sand-mudstone reservoir. The stress prediction method does not take into account the mechanical characteristics of coal rocks such as low Young's modulus, high Poisson's ratio, low strength, and easy deformation, which is significantly different from conventional sandstone and mudstone; (2) when predicting the stress of coal reservoirs Pay attention to the characteristics of coal and rock that are easy to deform, but the current in-situ stress factors are not fully considered in its prediction method, such as: coal seam deformation is affected by temperature, and temperature changes produce additional stress

This shows that no matter which of the above forecasting methods is used, there must be deviations between the results and the actual

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