Displacement of Water by Gas in Propped Fractures: Effect of Fracture Fluid Surface Tension, Viscosity, Proppant Wettability and Gravity.

摘要

Inefficient recovery of fracturing water used in multi-stage hydraulic fracturing operations is a growing industrial concern. Non-recovered water can be trapped in the tight rock matrix and/or in the complex fracture network. Trapped water can block the gas flow and damage the reservoir.;This study reports results of various drainage experiments conducted to identify the factors controlling water displacement in propped hydraulic fractures. We conduct two sets of drainage experiments. First set of experiments are conducted by using a proppant packed column which is saturated with frac-fluid. These experiments are used to investigate the role of proppant and fluid characteristics on fluid recovery. Second set of drainage experiments are conducted in a physical fracture model. These experiments are designed to investigate the role of gravity, drawdown, surface tension and proppant wettability on fluid recovery.;The results of this study suggest that gravity plays a dominant role in fracture cleanup and that water cleanup in fractures below well may be inefficient. Increasing the drawdown does not improve water recovery. Reducing surface tension and using treated hydrophobic proppant improves the sweep efficiency and in turn the load recovery.