Successful Fracture Stimulation in the First Joint Appraisal Shale Gas Project in China

This paper discusses fracture stimulation in the first joint venture shale gas project with foreign companies in China. Shell China Exploration and Production Company (SCEPCO) is jointly appraising the shale gas play with partner PetroChina. The block is in Sichuan, China. The target zone is Longmaxi hot shale, a Silurian formation. Its matrix permeability is extremely low, in the range of 100-300 nano-Darcy but rich in natural fractures. Hydraulic fracturing has been proven a key to enhance the production by effectively connecting natural fractures and providing a path for the gas to flow into the wellbore. “Every shale reservoir is different.” The joint working team is facing specific challenges in this play: 1. Understanding of reservoir based on the study of geology, petrophysic, geomechanics. 2. High wellhead treating pressure due to high formation stress and pore pressure. 3. Deep wells – some deeper than 3,500m TVD. 4. Fluid system and proppant type and size selection. 5. Fit for purpose treatment size and pump program. 6. Connection between wellbore and formation through the fracture. 7. Horizontal wells - Stimulation interval selection, stage spacing, perforating strategy. 8. Unknown fracture geometry - only 1 microseismic was applied in a horizontal well. Two vertical wells and three horizontal wells have been fracture-stimulated to date. The team has gained valuable experience and made significant improvement step-by-step and well-by-well. This paper discusses how a collaborative approach was applied to the completion of the shale gas wells during appraisal. Initial production test results of the wells have been promising. This is a significant step to unlock the potential of shale gas resources in China and help meet the country’s energy needs.