Coal-bed gas-content calculation method

Abstract

The invention discloses a coal-bed gas-content calculation method including: selecting a series of coal-core samples of a tested area; measuring a corresponding maximum vitrinite reflectivity Rmax of each coal-core sample and a well log value of each of corresponding well sections of the coal-core samples; establishing a relationship between the maximum vitrinite reflectivities Rmax and coal-bed gas-content parameters R; and establishing a calculation formula of the coal-bed gas content Vgas according to the well log values and the coal-bed gas-content parameters R. Through introduction of the vitrinite reflectivity, the coal-bed gas-content calculation method takes an effect of coal rank on the coal-bed gas content into full consideration so that the calculated coal-bed gas content complies with an actual geological condition in a better way. And at the same time, the coal-bed gas content is convenient to obtain and low in cost because of being capable of being obtained only based on the well logging information and the vitrinite reflectivity. Moreover, coal-bed gas content of continuous well sections can be obtained so that application effect is good.

Description

technical field [0001] The invention relates to the field of coalbed methane exploration and development, in particular to a method for calculating the gas content of coalbeds. Background technique [0002] Coalbed methane is a very important clean energy source in unconventional oil and gas. It has a large amount of resources, low degree of exploration, and great development potential. The exploration and development of coalbed methane is of great significance for increasing the effective supply of natural gas, improving the safe development and comprehensive utilization of coal and natural gas resources, and developing a green economy. In the process of coalbed methane exploration and development, coalbed gas content is one of the key parameters to evaluate the amount of coalbed methane resources. The coalbed gas content directly affects the formulation of the coalbed methane reservoir development plan. [0003] At present, in addition to measuring the gas content of coa...

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Problems solved by technology

[0013] Among the above several methods for calculating the gas content of coal seams, the statistical method is relatively simple and direct, but has the characteristics of inaccurate calculation results; the selection of background values ​​in the background value method is difficult, and it is difficult to obtain the background value of a coal seam completely free of gas; isothermal adsorption The method requires an isothermal adsorption test, and for the correction of ash and fixed carbon, it is necessary to analyze the industrial components of the coal core, and the acquisition process is cumbersome; the calculation result of the BP neural network algorithm is relatively accurate, but the calculation process is relatively complicated, and a large number of samples are required. study

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