Robust technique for real-time closure stress determination

To achieve credible engineering estimates of fracture geometry, fluid efficiency, and potential risks of premature screen-out, the engineer must reliably history match the observed net-fracturing pressure. Measurement of net-fracturing pressure requires first, and foremost, a reliable estimate of the formation closure stress, to which the net pressure is referred. This paper documents both the theory and several example field applications of a novel flow-pulse closure stress determination method. The flow-pulse technique requires only small changes in fracture treatment pumping schedule that can be accomplished at little to no extra cost, yet it allows a robust estimation of formation closure stress in real time. The flow-pulse technique involves pumping a small minifrac (usually with water) and then pumping small pulses (of about 5 bbl) of fluid during the pressure decline. There is a dramatic change in pressure response when flow pulses are pumped into an open fracture vs. a fracture that is already closed.