One-Run In Situ Stress Testing by Microfracturing Guides Hydraulic Fracturing, Antelope Shale

Introducing hydraulic fracturing to the Antelope Shale

An operator in the southern San Joaquin Valley needed in situ stress measurements to design effective completions employing hydraulic fracturing. Whereas the Monterey Formation produces from prolific natural fractures, its equivalent in the southern San Joaquin Valley, the Antelope Shale, is not naturally fractured. For the Antelope Shale to become a major unconventional resource, hydraulic fracturing would be necessary to replace the role that natural fractures playin the Monterey.

Directly measuring minimum stress magnitude in multiple intervals

The MDT modular formation dynamics tester effectively defines intervals for microfracture testing with the high-performance inflatable elements of the Dual-Packer Module. Even thin zones can be isolated between the packers for evaluation with small, controlled injection volumes. In a single trip in the well, multiple intervals can be efficiently individually tested. By measuring the formation's pressure response immediately downhole, the MDT tester avoids the frictional loss and time lag that compromise surface pressure measurement.

Designing effective fracture stimulation

Because fracture height is primarily controlled by the minimum in situ stress, measuring the contrast in the closure pressure during microfacture tests is critical. The operator gained a wealth of useful information in a single trip of the MDT tester by successfully determining the in situ stress for multiple intervals. These discrete measurements were used to calibrate mechanical properties derived from sonic logs for designing efficient, effective fracturing operations for the Antelope Shale.