Seismic Anisotropy Reveals Stress Changes around a Fault as It Is Activated by Hydraulic Fracturing

Predicting stress-induced anisotropy around a borehole

Formation elastic properties near a borehole may be altered from their original state due to the stress concentration around the borehole. This could result in a biased estimation of formation properties but could provide a means to estimate in situ stress from sonic logging data. In order to properly account for the formation property alteration, we propose an iterative numerical approach to c...

Location of Microearthquakes Induced by Hydraulic Fracturing

This paper examines the problem of locating microearthquakes induced by hydraulic fracturing using seismic arrival time data. In addition to the use of absolute arrival times measured for individual events, we consider the use of differential arrival times amongst a set of two or more seismic events as a means of constralning their locations relative to one another. Differential arrival times c...

Hydraulic and Pneumatic Fracturing

Crustal fracturing and presence of fluid as revealed by seismic anisotropy: case histories from seismogenic areas in the Apennines (Italy)

An automatic analysis code, Anisomat+, was developed, tested and improved to calculate anisotropic parameters: fast polarization direction and delay time. Anisomat+ was applied on data coming from three zones of the Apennines in Italy. For each area, anisotropic parameters have been interpreted to determine the fracture and stress field taking into account the geological and structural settings...

Energy Analysis of Hydraulic Fracturing

In this paper, numerical simulations of circular boreholes under internal hydraulic pressure are carried out to investigate the energy transferred to the surrounding rock and the breakdown pressure. The simulations are conducted by using a micromechanical continuum damage model proposed by Golshani et al. (2006). The simulation results suggest that the borehole breakdown pressure and the energy...