A Coal Reservoir's Energy Effect of a Different Gas System Under the Condition of Multi-coalbeds Overlay in Zhina Coalfield, China

Abstract

To the gas system of multi-coalbeds overlay in Zhina coalfield, the initial proposals about coalbed methane (CBM) exploitation, based on a large number of coalfield geological exploration data and the results obtained in coalbed methane exploration recently, was proposed through the analysis of coal reservoir's flexibility energy on horizontal and that of different gas systems on vertical, respectively. The study revealed that Zhongzhai exploration area is the independent gas system of multi-coalbeds overlay. The relation of methane flexibility energy and burial depth of a coalbed show intense fluctuations among the four gas systems, however, methane flexibility energy is increasing with burial depth of coalbed in every different gas system. Adopting subsection fracturing and drainage pattern, the first gas system was the best fit for CBM exploitation. Zhi-2 well, a unified gas system of multi-coalbeds overlay, is located in Zhuzang syncline, of which coal reservoir's flexibility energy is increasing with the burial depth. According to the coal seam spacing and flexibility energy, No. 16 and No. 23 coal seams should be exploited first between two sets and adopt the pattern of subsection hydraulic fracturing and multiple layer drainage.

Keywords:

• coalbed methane (CBM) exploitation
• coal reservoir's flexibility energy
• gas system
• multi-coalbeds overlay
• Zhina coalfield