Escaping Loss of Coalbed Methane during Production

Abstract

Abstract: This paper analyzes coalbed methane (CBM) preservation, accumulation, and the escaping loss during production, presents several factors to identify coalbed methane escaping loss by defining two parameters - escaping velocity ratio and escaping distance ratio. Then the escaping loss volume and distribution of CBM escaping are calculated by simulation. Meanwhile, the impact of surrounding rock permeability, initial entrapped gas volume in coal beds and gas production on CBM escaping loss volume are studied. If CBM escaping distance ratio is larger than the maximum CBM escaping velocity ratio, it is considered that CBM will not escape from coal beds. Case calculation shows that the escaping loss is likely to occur in the areas far from wellbore and 10%-15% of CBM reserves will be lost during production, and more than 10% of CBM reserves escapes during the early production stage. Relative low loss commonly occurs in the coal-beds with high and low CBM content, however, the coal-beds with intermediate CBM content may suffer relative high losses. Therefore, the key to reducing CBM escaping loss is to establish producing pressure-drop quickly in coal beds to realize rapid production at the early stage.

Key words: coalbed methane (CBM), preservation, liquid-phase adsorption, escaping condition, escaping velocity ratio, escaping distance ratio

ZHU Suyang, LI Chuangliang, DU Zhimin, LI Zepei, PENG Xiaolong. Escaping Loss of Coalbed Methane during Production[J]. Xinjiang Petroleum Geology, 2016, 37(zk(English) ): 81-86.

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