Natural Fracture Quantification for Optimized Completion Decisions

摘要

Natural fracture enhanced formations are one of the key parameters for commercial production from many of the unconventional gas reservoirs in North America. Natural fractures can enhance system permeabilities one to two orders of magnitude over matrix permeabilities, and enable economic production from unconventional sources. However these natural fracture systems can be very prone to damage from cementing and fracturing fluids, which can cause completion difficulties and greatly temper the productive potential from these wellbores. This paper presents a process for quantifying the natural fracture azimuth and porosity through fracture characterization logs, and uses this information to optimize the cementing and fracturing systems in order to minimize invasion damage and maximize the productive potential of these natural fracture systems. A customized natural fracture leakoff control package based on specific characterization of the natural fracture systems and properties can greatly reduce both the frac fluid invasion damage as well as decrease near wellbore frac gradient increases due to poroelastic leakoff effects. The result is naturally fractured reservoirs that can come much closer to their full productive potential with less secondary damage and near wellbore flow constrictions. In this paper we present example applications from the Piceance basin and the Greater Green River basin, presenting production data, fracture analysis as well as micro seismic evaluation