In low permeability gas reservoirs, hydraulic fracturing is often necessary to stimulate gas recovery and provide economic gas flow rates. A hydraulic fracture is created by pumping large volumes of high viscosity fracturing fluid containing a granular propping agent into the formation. The well productivity is improved by creating a highly conductive flow path from the formation to the wellbore. Achieving and maintaining sufficient fracture conductivity is critical to the optimization of gas recovery from hydraulically fractured wells. The purpose of this research is to study how certain factors affect fracture fluid clean-up behavior, well productivity, and ultimate gas recovery from hydraulically fractured wells.
Several studies have been performed to investigate fracturing fluid clean-up behavior and well productivity. A few studies have determined how various parameters affect fracturing fluid clean-up,1–6 while other studies have focused on the factors that affect the productivity of hydraulically fractured wells.7–10 The previous work defined some of the problems associated with the clean-up behavior and well productivity. We have extended the previous work to identify the reservoir conditions that determine how productivity is affected by clean-up behavior.
The objectives of this paper are: (1) to investigate the factors that affect fracture fluid distribution around a fracture; (2) to determine which factors most affect fluid clean-up behavior after a fracture treatment; (3) to quantify the factors that affect well productivity after a hydraulic fracture treatment; and (4) to provide recommendations concerning how to produce a well after a hydraulic fracture treatment to optimize gas recovery. This research was performed as part of the Tight Gas Sands Research Program sponsored by the Gas Research Institute (GRI) in Chicago, Illinois.