Method for determining gas contents of coal beds

Abstract

The invention discloses a method for determining gas contents of coal beds, and belongs to the field of coal bed gas exploration and development. The method includes forming theoretical values of Langmuir volumes corresponding to different coal rank conditions on the basis of Langmuir isothermal adsorption theoretical model derivation; applying corresponding conventional well logging data on the basis of the theoretical values, combining the well logging data with coal and rock test analysis and isothermal adsorption experiment data and quantitatively computing and determining the gas contents of the coal beds. The method has the advantages that Langmuir isothermal adsorption models are improved, relations between the maximum vitrinite reflectance and the Langmuir volumes are analyzed, a process for solving the maximum vitrinite reflectance by the aid of conventional well logging curves is created, and accordingly the gas contents of the coal beds can be determined; the method is continuous in evaluation and cognition, good verification effects can be realized, shortcomings of difficulty in experimental sampling and excessively high cost due to the fact that gas contents are measured by the aid of existing experimental technologies at present can be effectively overcome, and reliable reservoir parameters can be provided for developing coal bed gas in various basins in China.

Description

technical field [0001] The invention relates to the field of coal seam gas exploration and development, in particular to a method for determining the gas content of coal seams. Background technique [0002] Coalbed methane is an unconventional energy source, and the quantitative prediction of its coal reservoir gas content is the key to evaluation. With the deepening of coalbed methane exploration in many basins in my country, a series of methods for evaluating coalbed methane content have been accumulated, but they are still far from meeting the needs of coalbed methane exploration and development. At present, the problem to be solved is how to quantitatively evaluate the gas content of coal seams based on multi-parameter data of well logging. Domestic and foreign researches are mainly based on establishing the relationship between density and ash content, and then establishing the relationship between ash content and gas content. The calculation results are largely affecte...

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Problems solved by technology

The single-parameter regression method considers a single factor, so the calculation is fast, but the calculation error is large (the input curve is easily disturbed by the outside world), and the correlation is poor

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