Abstract: Methods and related systems are described for measuring acoustic signals in a borehole during a fracturing operation. The system includes a downhole toolstring designed and adapted for deployment in a borehole formed within a subterranean rock formation. A downhole rock fracturing tool opens and propagates a fracture in the subterranean rock formation. Dipole and/or quadrupole acoustic sources transmit acoustic energy into the subterranean rock formation. A receiver array measures acoustic energy traveling through the subterranean rock formation before, during and after the fracture induction. Geophones mounted on extendable arms can be used to measure shear wave acoustic energy travelling in the rock formation. The toolstring can be constructed such that the sources and receivers straddle the fracture zone during the fracturing.

Abstract: A method and system is described for estimating stress characteristics from seismic data. The method includes receiving seismic data acquired over a region, receiving properties of rock at a location within the region, and estimating one or more stress characteristics for a sub-region by combining the seismic data and the rock properties using a relationship between the stress characteristics in the sub-region and elastic stiffness and/or sonic velocity in the sub-region. The relationship is based on a non-linear elasticity theory.

Abstract: A method and system is described for estimating stress characteristics from seismic data. The method includes receiving seismic data acquired over a region, receiving properties of rock at a location within the region, and estimating one or more stress characteristics for a sub-region by combining the seismic data and the rock properties using a relationship between the stress characteristics in the sub-region and elastic stiffness and/or sonic velocity in the sub-region. The relationship is based on a non-linear elasticity theory.