Evidence of Horizontal Hydraulic Fracture at Depth Due to Stress Rotations Across a Thrust Fault

Abstract

fax 01-972-952-9435. AbstractMicroseismic imaging of a hydraulic fracture stimulation showed significant fracture reorientation across a thrust fault. Fracture orientations were identified through a combination of alignment of event locations, polarization of the seismic waves and injection details. Stimulation below the fault indicated a near horizontal fracture geometry. Above the fault, a near vertical fracture geometry was observed. A change in fault orientation was supported by differences in the microseismic signal characteristics and the treatment injection data. This difference in fracture geometry was attributed to rotations in the direction of minimum principle stress, which is consistent with observed differences in the injection pressures. The fracture reorientation suggests a significant difference in the stimulated permeable pathways for sands above, compared to below the fault.

Analysis of Fracture Design in a Vertical Well with a Horizontal Fracture

“…In addition, in-situ stress state change due to geological movements (e.g. a thrust fault) (Maxwell et al 2007), secondary or enhanced oil recovery (Wright et al 1997;Wong and Chau 2004) may result in significant growth of horizontal fractures during fracturing. Daal and Economides (2006) studied hydraulically fractured wells in square and rectangular patterns, and they concluded that a dimensionless fracture conductivity of 1.6 will yield the highest productivity for production systems with proppant number below 0.1.…”

Horizontal vs. Vertical Borehole-based Microseismic Monitoring: Which is Better?

“…Microseismicity can be used to track fracture geometry, height, length, and complexity, and be used to assess if the stimulation has interacted with a geohazard 1,2,3,4 . In order to realize the production potential of a horizontal well, it is necessary to maximize reservoir contact through properly designed stimulations 3 .…”