Development of a Static Reservoir Model for the Niagara-Lower Salina Reef Complex of the Guelph Formation, Michigan Basin

Abstract

Silurian-age Niagaran “pinnacle reefs” of the Michigan Basin host an immense hydrocarbon resource, existing as closely-spaced, highly-compartmentalized reservoirs that have produced >500 million barrels of oil and 2.9 trillion cubic feet of natural gas. Many of these fields are approaching or have already passed economic viability of primary production, but the high degree of compartmentalization makes them a potential target for CO₂ enhance oil recovery, as well as natural gas storage. The primary objective of this study was to produce a geologically precise 3D static model of the Columbus III Niagara-Lower Salina Reef Complex, which could be used as the fundamental input for dynamic fluid-flow modeling for a cyclic gas injection-withdrawal project in St. Clair County, Michigan. A high density of 32 cored wells at 20-acre spacing within the reef complex, thin-section petrography, and wire-line logs were used to identify depositional and diagenetic facies in order to define reservoir flow units. Despite facies changes dictating the upper and lower flow boundaries within the model, individual flow units were defined by diagenetic alteration, including dolomitization, blocky calcite cements, and pervasive salt-plugging. Rock properties within the 3D static reservoir were populated using porosity-permeability data obtained from conventional whole core analysis. The validity of the modeled HC volume estimates, which were calculated from porosity, fluid saturations, and fluid contacts, was confirmed by a near exact match with pressure-derived estimates provided by the field's operator. This study highlights the importance of using sequence stratigraphy and rock typing to define reservoir flow units for static reservoir models.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016