Study on spatial distribution of coalbed methane contents in coal seams based on key interpolation points: an example from Shizhuang South block in, Shanxi Province, China

Abstract

At present, the method of “experimental gas content + multi logging parameters and coalbed methane (CBM) content fitting + exploration network” is commonly used to obtain the spatial distribution law of coal seam CBM content. When the heterogeneity of CBM content in coal reservoir is strong, the results obtained by traditional methods are obvious different from the actual results. In the present work, taking Shizhuang south block in Shanxi Province, China as an example, 26 key points controlling the CBM content in the 3# coal seam in the study area are identified by combination of inversion of structural features and use of gas–water differentiation theory. Which avoids that the traditional "exploration network" cannot accurately identify the maximum/minimum point of CBM content. The regression of isothermal adsorption parameters and logging curves were used to obtain CBM contents at key interpolation points. The spatial distribution characteristics of CBM content are obtained by “Kriging interpolation method.” Randomly selected points, and intersection points on the exploration network, all with a same quantity of points were compared. The results show that the prediction results by key points are more approximate to those obtained with more points.

Keywords:

• coalbed methane content
• gas–water differentiation
• inversion of structural features
• the maximum/minimum point

Additional information

Funding

This study was supported by the Program for Innovative Research Team (in Science and Technology) in Universities of Henan Province, China (Grant No.21IRTSTHN007) and The Program for Innovative Research Team (in Science and Technology) of Henan Polytechnic University (GrantNo.T2020-4).