Pressure Variations Inside the Hydraulic Fracture and Its Impact on Fracture Propagation, Conductivity, and Screenout

Abstract

Abstract Field measurement of fluid pressure inside hydraulic fractures have shown rapid pressure decline along fracture length. The consequence of this pressure profile is rapidly tapering fracture width. This means that a disproportionate volume of fluid and proppant injected inside hydraulic fractures remain near the wellbore, thus creating excessive near wellbore and substantially less far field fracture conductivity. This explains why history matching of oil well productions yields much lower effective fracture lengths than gas wells, since oil wells because of their higher permeability require higher fracture flow capacity. The rapid tapering of the fracture width also restricts the movement of the proppant inside the fracture, causing its accumulation near the wellbore. As the treatment progresses, and if sufficient proppant volume has been injected inside the fracture, the near wellbore segment of the fracture can begin to fill with proppant, thus reducing the open width available for further movement of the fluid. Essentially, accumulation of proppant near the wellbore reduces the fracture width available for fluid flow which then results in higher frictional pressure losses inside the fracture, further skewing the pressure distribution, and eventually screen-out.