The recovery of unconventional gas fields especially the shale gas is of great significance to clean energy supply. High productivity of shale gas is attributed to the large-scale hydraulic fracturing with high operating pressure (80-100MPa) and discharging rate (14-18m3/min). More high-horsepower fracturing vehicles driven by diesel engines result in higher CAPEX. The low operation efficiency and unexpected maintenance negatively affected the economics performance of operators due to unacceptable OPEX. The fully electric-powered hydraulic fracturing solution was proposed as the alternative to the diesel-engine fracturing vehicles in this article. The skid-based electric pumping units were newly developed with advantages of high power density (6000HP per unit), Variable Frequency Drive (VFD) modules integration, fuel cost saving, low maintenance expenditure and eco-friendly operation. The field application was conducted in one pad of N209 in shale gas field, Sichuan, China.
The electric-powered system, consisting of pumping units and blenders with other facilities, was deployed on the operation site. One large-capacity electric power grid (35kV and 30000kVA) was constructed for both drilling and massive multistage fracturing. The operation team successfully performed all hydraulic fracturing jobs as required with 7.4×105 kWh of total power consumption. The system functioned reliably without large faults occurred.
The electric-powered solution was comprehensively evaluated and compared to the diesel-engine fracturing solution in terms of CAPEX, operational efficiency, power consumption, maintenance and fleet crew cost. The novelty of the technology is the fully electric-powered hydraulic fracturing system with large-capacity electric power grid. It is concluded from the field application that the electric-powered fracturing technology is qualified for unconventional reservoirs development.