Simulation of Water Influx and Gasified Gas Transport during Underground Coal Gasification with Controlled Retracting Injection Point Technology

Underground coal gasification (UCG) may change the energy consumption structure from coal-dominated to gas-dominated in years come. Before that, three important problems need be solved, including failure of due large amounts water pouring into gasifier, environmental pollution caused by gas migration surface, and low calorific value poor control degree gasification. In this study, a geological model is first established using computer modeling group (CMG), commercial software package for reservoir simulation. Then, inflow seam gasifier during controlled retracting injection point (CRIP) process simulated based on model, maximum instantaneous too. Meanwhile, gasified also simulated, discipline different gases shown. Finally, pressure distributions two stages are presented, pointing out dynamic characteristics UCG process. The results show that (a) cavity width, production pressure, negatively correlated with inflow, while initial formation floor aquifer energy, temperature positively correlated; (b) CO2 mainly concentrated near well largely does not migrate upward, O2 migrates upward slowly, CH4, CO H2 relatively quickly. When injection–production difference 2 MPa, it takes 33.5 years, 40 44.6 CO, depth 1000 m 200 m, respectively. increases 4 rate about two-fold. (3 MPa) above outcrop can slow down 0.03 m/day; (c) changes more significantly than well. overall rises width increases, distribution always presents an asymmetric unimodal receding point. simulation work provide theoretical basis operation parameters design monitoring deployment, ensuring safety reliability on-site