Potential Shale-Oil Reservoirs in the Eastern Bighorn Basin, Wyoming

Abstract

The identification of new oil-producing shale reservoirs can be facilitated through the application of full 3-D petroleum system modeling. This study presents the results of a full, 3-D petroleum system model of the Bighorn Basin, north-central Wyoming, and the identification of potential shale oil reservoirs that are currently not being produced. Multiple data types were obtained and integrated into a single, large-scale 3-D model which was used in the petroleum systems simulation. Calibration was then performed to improve modeling results. This study was performed in five phases – 1) 3-D structural framework construction, 2) geochemical data integration, 3) preliminary 1-D simulations, 4) 3-D predictive model simulation and 5) calibration. Previously studies utilized 1-D petroleum models which are limited geographically. This study utilized advanced 3-D modeling techniques to simulate the basin’s geologic history from the Precambrian to present day. Results indicate that the Permian petroleum system has a high degree of thermal maturity, however, the drill depth to these formations make them currently uneconomic for development. The model indicates that the Lower Cretaceous formations also have a high degree of thermal maturity and the thermal maturity decreases upwards into the Upper Cretaceous formations. Based on the structural framework developed as input for the modeling process and the calibrated thermal-maturity results, the base of the marine Cody Shale and the upper portion of the marine Frontier formation, which includes shales, have been determined to be within the oil generation window and economic drill depths in the eastern Bighorn Basin.

AAPG Datapages/Search and Discovery Article #90357 ©2019 AAPG Rocky Mountain Section Meeting, Cheyenne, Wyoming, September 15-18, 2019