Surface Microseismic Monitoring for Over 30 Wells in Changning Region Sichuan Shale Gas Play, China: The Discoveries

Abstract

Abstract The surface microseismic monitoring technology has been utilized in Changning region Sichuan shale gas play for over 30 wells since the beginning of 2018. The microseismic events located in real time could help to optimize the pump schedule, estimate the diversion, and mitigate engineering risks. The wide coverage of the geophone channels allows for moment tensor inversion (MTI) which reveals the source mechanism, and so to identify the natural fractures more accurately. The property of the microseismic events were integrated with the pump data, the completion design, the reservoir properties, the ant tracking results, as well as the production. The purpose was to find the optimum completion and fracturing design parameters, and more importantly to figure out which factors contribute the most to production. The MTI result provided more accuracy on identifying the natural fractures which are key for hydrocarbon flow but at the same time also bring challenges for hydraulic fracturing operation. The surface microseismic monitoring technique provides decent results for reservoirs with TVD range of 2100-3850m in Changning region. The number and magnitude of microseismic events is dependent on natural fractures. The higher pump rate tends to generate fracture network with bigger width and so higher complexity and to achieve higher estimated stimulated volume (ESV). The MTI properties could help to identify natural fractures more accurately and calibrate the ant tracking results. The relative angle and distance of natural fractures to the well trajectory influences the ESV and so the production. The ESV of a single stage barely shows relevance to the production log, but the ESV of a well does illustrate relationship with production of the well, especially the accumulated production of 3 months. The rich data of surface microseismic monitoring in over 30 wells in Changning region leads to better integration for reservoir properties, completion and fracturing design, microseismic properties, natural fractures as well as the production.