Analyzing, Optimizing Frac Treatments By Means of a Numerical Simulator

Abstract

Technology Update Hydraulic fracturing and refracturing has become an integral part of completing wells, especially in unconventional reservoirs such as tight gas formations, shale, coalbed methane, and tight oil reservoirs. Practicing reservoir and production engineers now require access to a well-completion simulator. This completion simulator should have the ability to simulate productivity of complex reservoirs and wells, not only to design an optimum fracturing treatment but also to analyze production results. For a practicing engineer, the prediction of productivity of fractured wells requires a balance between accurate representation of the physical process of reservoir fluid flow and the time required to simulate that process. Because unconventional reservoirs and associated wells can be complex, analytical solutions are usually not capable of providing an adequate prediction of the well performance. The need for a comprehensive, yet easily accessible, numerical simulator for well-completion processes has become a necessity. The basic philosophy behind such a simulator is that it would Emphasize prediction of a small number of wells, including the capability of predicting single-well production and performing related analysis. Provide higher speed in both simulation and turnaround rate. This goal can be achieved through the use of a graphical user interface. Some of the more complex features may be accessible to more sophisticated users by means of special file handling to enhance analysis capability. Automate the simulation of specialized features that may be crucial to stimulation. These features include the following: Consideration of the fracturing-fluid filtrate as a separate aqueous fluid Linkage to a commercially available proppant library Ability to import fracture geometry and properties, including proppant concentration and type, fracture width, and amount of fluid leakoff into the formation for each fracture grid from commercially available fracture-design simulators—specifically, the 3D design programs StimPlan (NSI Technologies) and GOHFER (Barree and Associates)