Stress, seismicity, and microseismic source mechanisms at the Hydraulic Fracture Test Site-1 in the Midland Basin, TX
Abstract
We investigated the relationship between borehole stress measurements and microearthquakes resulting from hydraulic stimulation at the Hydraulic Fracture Test Site-1 in the Midland Basin, TX. The project is comprised of two sets of horizontal wells in the Upper Wolfcamp (UWC) and Middle Wolfcamp (MWC) shale units. Following hydraulic fracturing, a slant well was drilled to core the area where hydraulic fracturing and microearthquakes occurred.
Regional patterns of stress indicate that the area is in a normal/strike slip faulting regime. Diagnostic formation integrity tests (DFITs) in vertical and horizontal wells constrain the pore pressure and the minimum principal stress, Shmin. Above the UWC, the Shmin gradient (hydraulic fracture gradient) is close to the drilling mudweight, creating a normal faulting regime. In the UWC, Shmin increases with depth, resulting in a transition to strike slip faulting, then decreases with depth, returning to a value consistent with the gradient in overlying units. In the MWC, Shmin varies between the high and low hydraulic fracture gradients, indicating lithofacies with alternating high and low differential stress. Instantaneous shut-in pressures from hydraulic fracturing stages corroborate the vertical stress variations reflected by DFITs.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMMR0030016K
- Keywords:
-
- 1822 Geomechanics;
- HYDROLOGY;
- 3610 Geochemical modeling;
- MINERALOGY AND PETROLOGY;
- 3612 Reactions and phase equilibria;
- MINERALOGY AND PETROLOGY;
- 5139 Transport properties;
- PHYSICAL PROPERTIES OF ROCKS