The Optimization of the Coalbed Methane Assessment Indexes in the High Abundance Coalbed Methane Enrichment Area in the Case of the Southern Part of the Qinshui Basin, China*

To seek the blocks for the coalbed methane (CBM) development and acquire the gas wells with the higher productivity are the final goals of the assessment on the high abundance CBM enrichment area. Based on the CBM geological conditions, reservoir conditions and CBM well productivity situations, to approach various factors impacting the CBM well productivity, and finally, the limit values of the assessment indexes on the high abundance CBM enrichment area are: the enrichment areas are located mostly in the groundwater stagnant area with the syncline structure and simpler hydrogeological conditions; the seam buried depth is shallower, permeability > 1md; gas-bearing saturation degree > 70%; reservoir pressure gradient > 0.5 MPa/100m; and daily gas production of single CBM well > 2000m3/d.