Gas source and contribution identification for coal measure gas commingled production in Wulihou mining area

Abstract

Determining the gas source and contribution in coal measure gas commingled production lays the foundation for developing commingled production schemes. Based on coal measure gas exploration and development data from the Wulihu mining area in the Lu’an mining area, carbon and hydrogen isotope tests of CH4 from the No. 3+4 coal measure strata and the No. 15 coal seam were conducted. Using a binary gas source model, the gas source and proportions of six commingled wells were identified. Additionally, considering factors such as gas content, permeability, and desorption capacity, the production contributions of gas from the No. 3+4 coal measure strata and the No. 15 coal seam in three commingled wells were calculated based on catastrophe theory. The results showed that when isotopic differences in carbon and hydrogen values were observed between multiple gas-producing layers, these differences could be used to determine the source and proportion of gas from each layer. When the No. 3+4 coal measure strata consistently produced gas while the No. 15 coal seam did not desorb gas, the produced gas entirely originated from the No. 3+4 coal measure strata. When both the No. 3+4 coal measure strata and the No. 15 coal seam stably produced gas, the gas productions were 42%-45% and 55%-58%, respectively. The production split coefficients calculated based on catastrophe theory closely matched experimental results, confirming the feasibility of this method. This study provides a method and reference for accurately identifying gas sources and contributions in coal measure gas commingled production for this mining area.

Keywords

• |coal measure gas commingled well|gas source|gas production contribution|carbon and hydrogen isotopes|catastrophe theory