Discussion on commercial recovery of shale gas and equipment configuration

Shale gas is a high-efficiency, clean fossil fuel. In China, the efficient and extensive exploitation of shale gas is restrained by the complex reservoir conditions, immature recovery technology and high comprehensive recovery costs. Therefore, developing a practical commercial recovery mode of shale gas and scientifically configuring drilling and production equipment are critical to cost-effective, large-scale, high-efficiency and low-carbon recovery of shale gas, which is exactly the goal that has been pursued by both China and other countries over recent years. In this study, the difficulties and challenges in shale gas development were analyzed, and the experience of shale gas development in China and other countries and the differences in implementation conditions were summarized. Finally, the shale gas drilling and production engineering concept and operation mode featured with overall planning, areal development, network building first, gas power generation, combination of gas power generation and power grids, comprehensive utilization, electric drive, line work and factory-like production were proposed. The well site equipment are configured as follows: (1) for aggressive drilling with high WOB, fast rotation, high pump pressure and rates, and large torque, the high-efficiency and low-pollution frequency-variable drilling rig is preferred to extend horizontal wellbores to more than 2,000 m and greatly expand the capture of pay zones; (2) high-power electrically-driven fracturing pumps are adopted to meet the requirements of long-time, high-rate, long-stroke and continuous fracturing operations, which helps to increase stimulated reservoir volumes and fracture network density and enhance oil recovery; (3) the frequency-variable proppant mixing system is used to deliver automatic storage, transportation and mixing of proppants; and (4) the distributed gas power stations are built and use local gas sources for the relay of power generation, which ensures stable, flexible, low-cost and environment-friendly power supply, and full electrical driving coverage of well site equipment and "gas power generation for gas recovery and combination of gas power generation and power grids". These efforts greatly reduce the costs of equipment, site footprint, operation pollution and fuel consumption, effectively improve the utilization rate of equipment and reduce the costs of shale gas development.