Microseismic Fracture Mapping Optimizes Development of Low-Permeability Sands ofthe Williams Fork Formation in the Piceance Basin

摘要

Williams Production Company performed a study to improvernhydraulic fracturing and field development in the WilliamsrnFork Formation, Piceance Basin, Colorado. The WilliamsrnFork Formation is part of the Mesaverde Group and consistsrnof massively stacked low permeability sandstones. Wells inrnthe Williams Fork are usually stimulated in multiple fracturernstages using limited entry techniques. This paper describesrnhow hydraulic fracture mapping was performed withrnmicroseismic imaging on two wells in the Grand Valley Fieldrnand two wells in the Rulison Field. This was part of a pilotrnproject to assess well downspacing and to assist withrnstimulation optimization. Fracture length was longer thanrnexpected but varied somewhat by field, well and treatmentrntype. Payzone coverage was good considering significantrndifferences exist in breakdown and pore pressures of thernvarious sands within the hydraulic fracture stage. Fracturerninitiation and early growth did not fully correlate with porernpressure and ISIP data from diagnostic injections but overallrnpayzone coverage generally matched this data.