Locating high-productivity areas of tight gas-sand reservoirs using LF seismic surveys at Jonah and Pinedale fields.

Birkelo, B., A. Goertz, and K. Cieślik, Spectraseis AG and E. LaBarre, EnCana Oil & Gas (USA) Inc

 

Jonah and Pinedale fields in southwest Wyoming are prolific tight gas reservoirs. Jonah may have up to 8 TCF of recoverable gas, and estimates at Pinedale exceed 27 TCF. Primary production is from more than 5000 feet of discontinuous, sandstones from Upper Cretaceous Lance and Mesa Verde Formations. A low-frequency passive seismic survey was acquired over the Jonah and Pinedale gas fields to verify whether changes in the ambient seismic wave field could discriminate the higher productivity areas. The 2D profiles of the survey crossed the field in places that show maximum contrast in well productivity. As part of the ambient wave-field characterization (AWC) processing, the anthropogenic noise generated by the operations and the infrastructure of the field was captured and analyzed. Results of this analysis show that the AWC seismic attributes correlate well to reservoir properties like estimated ultimate recovery (EUR) and hydrocarbon pore thickness (HPT or SgPhiH) while the anthropogenic noise was not responsible for the measured AWC seismic signal anomaly. This opens the door to the use of AWC seismic surveys to extend existing tight gas-sand fields and to locating the high-productivity areas in tight gas-sand exploration plays.