Integrated Stratigraphic Controls for Flow Simulation of the Wall Creek Member in the Frontier Formation: Western Powder River Basin, Wyoming

Abstract

Abstract The Frontier Formation in the Powder River Basin has been re-discovered for oil and gas potential with the development of long horizontal wells and multi-stage hydraulic fracturing. Over the last decade, the Wall Creek member (WCM) of the Frontier formation has proven to be a successful hydrocarbon-producing target, yet a full understanding of the flow behavior of this complex stratigraphic unit has not been fully achieved. The fluid and rock properties have uncertainty and are not well defined due to the low permeability rocks. This study aims to describe the fluid flow behaviors of these features and create an outcrop model that includes all the reservoir properties and geologic features to better understand hydrocarbon recovery. This project consists of two distinct aspects: (1) defining the reservoir properties through a well flow model and (2) upscaling the permeability of the reservoir models with different geologic features into an outcrop model for the WCM. A single horizontal well flow simulation model was created to estimate the reservoir properties. Using three offset well logs, a 32 feet interval was selected to represent the net pay zone of the Wall Creek. The porosity was estimated using well logs, and permeability was established by applying a correlation of porosity and permeability found from core data. The historical production data was matched by modifying the initial fluid saturations and the rock physics parameters such as relative permeability and capillary pressure. As a result, representative fluid and rock physics models were obtained for the outcrop model. From the outcrop study, defined geologic models with different facies of Wall Creek member were created to include abundances and orientations of mud drapes as the most impacted features that may affect the the fluid flow ability. An outcrop model captures fine heterogeneities of all the facies using flow-based upscaling of the geologic models. The effective directional permeabilities of each facies were obtained to integrate into an outcrop model to capture the geologic features that may have a large impact on the hydrocarbon recovery. In this work, we developed methods to incorporate fine-scale (cm) geologic observations from the outcrop with well scale properties from the field in an integrated study that was ultimately used to help determine field level decisions such as well spacing and fracture spacing.