Control of Superimposing Types and Distribution of Coalbed Methane Caprock by Sedimentary Environments in Shanxi Province

Abstract

Based on the geological data of 273 coalbed methane caprocks in 125 coal mines in Shanxi Province, the superimposing types of caprock were divided, and the distribution characteristics of different superimposing types were discussed. Considering the combination of lithology and rock compactness, the coalbed methane caprocks are divided into 4 superimposed types according to the rock formation structure, 11 superimposed subclasses according to the degree of rock compactness. Based on the paleo-sedimentary environment, the distribution characteristics of different superimposing types were analyzed. The composite caprocks were mainly distributed in the southwest Datong Coalfield, the north-central part of Ningwu Coalfield and the northeast Qinshui Coalfield; the thick integral caprocks were widely distributed in the northeast of Datong Coalfield, the northern part of Ningwu Coalfield, and the eastern edge of Qinshui Coalfield; the close coal seams caprocks were mainly distributed in the middle of Hedong Coalfield, east of Huoxi Coalfield and northeast of Xishan Coalfield; the thin-layer caprocks appeared only in the eastern edge of the Qinshui coal field.

Keywords

• coalbed methane
• caprock
• superimposing types
• ancient sedimentary environment
• distribution characteristics