CO2/ENHANCED OIL RECOVERY (EOR) AND GEOLOGICAL CARBON STORAGE (GCS) POTENTIAL: MIDDLE DEVONIAN, RICHFIELD MEMBER, (LUCAS FORMATION, DETROIT RIVER GROUP), MICHIGAN BASIN, USA

The Middle Devonian Richfield Member (Lucas Formation, Detroit River Group) is an important oil producer in the Michigan Basin. This unit occurs in the subsurface across most of the central Michigan basin and extends to a subcrop to the north, below glacial till, near the Straits of Mackinac. The Richfield Member consists mostly of dolomitized, subtidal to supratidal wackestone to packstone, minor grainstone, and alternating layers of anhydrite. The most common reservoir type is a classic high porosity-low permeability (15%-30% Ø and 5-25 md), peritidal, algal laminated, dolomicrite. Anhydrite dominates in younger strata, while interbedded anhydrite (caprock) and dolomicrite (reservoir) cycles lower in the section constitute ideal drilling targets. Initial oil and gas production from the Richfield began in 1939 with cumulative primary production from over thirty fields in excess of 55 MMB. Secondary recovery in several larger fields has been very successful with incremental oil production during water flooding ranging from 16%-83% of cumulative primary production. As mitigation of point source, industrial scale, greenhouse gas emissions becomes more critical the merits of geological CO2 sequestration in large volume, deep, saline formations are gaining credibility. Deep saline reservoir storage of CO2 has no direct by-products of value to offset the cost, but in conjunction with CO2/EOR is much more economically viable. Due to the production characteristics and reservoir petrophysical properties, dual CO2/EOR and saline reservoir geologic carbon storage in the Richfield Member has great potential in the Michigan basin. The research goal was to characterize the CO2/EOR and saline reservoir CO2 sequestration potential of the Richfield Member in the Michigan basin. Research methods include the evaluation of individual well and field production data and the reservoir quality characteristics of wells on and off oil producing structures. Core analysis, well log data, thin sections and porosity/permeability plots were examined to produce detailed petrophysical profiles. In addition to analysis of individual oil producing wells and fields, petrophysical properties in key wells across the Michigan Basin aided in constraining the regional CO2 sequestration potential of the Richfield Member.