Preliminary selection of target intervals for coal measure gas development in Linhua multi-coal seam field of northern Guizhou

The primary method for the target strata of coal-measure gas development in Linhua coalfield is proposed. The primary procedure of Linhua coal measure gas target strata is divided into two parts: geology and engineering. The specific process is as follows: combining with the sedimentary environment, based on dividing the gas-bearing system; the coal structure, brittleness index and the mechanical properties of surrounding rock are used as the evaluation indexes of engineering constraints to determine the primary target strata of coal measure gas development. The results show that the coal measure strata of Longtan Formation in the study area belong to reductive deposition under sea and land cross-deposition, which has the characteristics of “the thickness of single coal layer is thin, and the inter-bedding of coal measure gas reservoir is frequent”. According to the coal-rock gas-bearing property and coal-rock combination, three coal measure gas reservoir combination models and four gas-bearing systems can be divided. The gas-bearing systems have obvious reservoir physical property differences. It is considered that Ⅰa(958-968 m), Ⅱb(942-955 m), Ⅱc(910-933 m), Ⅲd(878-904 m) and Ⅳe(864-876 m)strata can be used as the priority target strata for coal measure gas co-production.