Abstract: A method for determining change in stress in a reservoir formation includes inducing a pressure pulse in a first well hydraulically connected by a fracture to the reservoir formation. A stress-related attribute of the fracture is determined from reflection events detected in pressure measurement made in the first well as a result of the inducing the pressure pulse. The inducing and determining are repeated to estimate changes in the stress-related attribute with respect to time. A method for determining and localizing type of interaction between a treated well and an observation well by monitoring pressure and fracture changes in the observation well.

Abstract: A method for determining properties of hydraulic fractures from measurements of pressure in a well made after stopping pumping fracturing fluid into the well (shut in) includes determining a first time after shut in whereinafter a decrease in measured pressure is caused by fluid leak off in a fracture. A second time after shut in is determined whereinafter the decrease in pressure is caused by fluid leak off, fracture growth and fluid pressure equilibration in the fracture. A third time after shut in is determined whereinafter the decrease in pressure is caused by fluid leak off, fracture growth, fluid pressure equilibration in the fracture and pressure drop in a near wellbore zone. Values of fluid efficiency, minimum stress and net pressure which are determined result in a calculated pressure with respect to time matching the pressure measurements within a predetermined threshold.

Abstract: A method for determining change in stress in a reservoir formation includes inducing a pressure pulse in a first well hydraulically connected by a fracture to the reservoir formation. A stress-related attribute of the fracture is determined from reflection events detected in pressure measurement made in the first well as a result of the inducing the pressure pulse. The inducing and determining are repeated to estimate changes in the stress-related attribute with respect to time. A method for determining and localizing type of interaction between a treated well and an observation well by monitoring pressure and fracture changes in the observation well.