Fluid energy characteristics and development potential of coalbed methane reservoirs with different synclines in Guizhou, China

Abstract

Reservoir fluid energy is an important parameter that restricts the productivity of coalbed methane (CBM), and is crucial for CBM exploration and development. In this study, data from 41 pumping tests and 37 water quality analyses from 8 syncline coal-bearing strata in Guizhou were collected. The results show that the equivalent reservoir pressure increases linearly with an increase in burial depth. The Changgang (CG) syncline belongs to an overpressure reservoir, the Yizhitang (YZT) syncline and the Yangmeishu (YMS) syncline belong to low pressure reservoirs, and the other syncline reservoirs are close to neutral pressure states. The hydrodynamic conditions of the Panguan (PG), Tucheng (TC) and Dahebian (DHB) synclines are stronger, those of the CG syncline are weaker, and those of the Huangnitang (HNT), Bide (BD), YZT and YMS synclines are relatively normal. The water quality types are divided into three types, namely, NaHCO3, Ca(HCO3)2 and CaSO4. The water quality for the CG, DHB, TC, PG and YMS synclines are of the NaHCO3 types, which shows a relatively closed groundwater environment. The water quality types of the HNT and YZT synclines are of the Ca(HCO3)2 type, which shows a relatively open groundwater environment. The water quality for the BD syncline are of the NaHCO3 and CaSO4 types, which indicates that the groundwater environment of coal-bearing strata in the BD syncline is complex and has the characteristics of both closed and open mixed environments. Furthermore, the principal component analysis method (PCA) was used to select 6 parameters and to select the DHB syncline as having the most development potential, followed by the PG syncline and the TC syncline. Validating these results with CBM development wells, the evaluation results were found to be in good agreement with the actual productivity of the CBM wells.