Technological Innovations for Hydraulic Fracturing Method for Stress Measurements With Wireline Formation Testers

Abstract

Measuring the state of stress in rock formations is important in many industries, with applications ranging from radioactive waste disposal and carbon storage sites to reservoir management and geomechanical modeling in the oil and gas industry. Hydraulic fracturing is a reliable technique and a direct method for measuring the magnitude of the minimum horizontal stress in the subsurface. Using wireline formation testers, this method relies on isolating an interval with inflatable packers and creating hydraulic fractures by injecting fluid into the formation and analyzing the pressure responses for multiple cycles of fracture propagation and pressure falloff to identify fracture closure and measure closure stress. There have been significant improvements in wireline formation stress testing and the performance of inflatable dual packer systems in recent years. This has resulted in development of wireline formation stress testing systems that can inject fluids for fracture initiation and propagation at differential pressures up to 6,000 psi in an 8.5-in. borehole. However, there are still technical needs for packer systems with increased pressure ratings and better compliance, as well as requirements for higher pump rates and flow control. To increase the differential pressure capability, dynamic sealing, and system compliance for stress testing in formations with higher stress conditions and breakdown pressures, a new dual packer architecture and redesigned mandrel assembly has been developed and engineered. The high-pressure packer and mandrel system that is capable of up to 10,000-psi differential pressure can be fitted to upgrade existing wireline formation stress testing systems. This system also provides better test interval isolation and compliance to reduce interval compressibility and interval volume variation to enable more accurate interval pressure measurements during hydraulic fracturing tests. In this contribution, we review the engineering and laboratory testing that was performed to validate the new wireline stress testing assembly and packer designs and the seal and retraction performance. We also describe field results and the practical application of the new system during its field application and provide a comparison with previous wireline stress testing technologies to highlight the improvements