Assessment of CO2‐enhanced oil recovery and associated geologic storage potential in the Michigan Northern Pinnacle Reef Trend

This paper provides an improved estimate of CO2‐EOR (where CO2 is carbon dioxide and EOR is enhanced oil recovery) and CO2 storage potential for depleted oil fields in Michigan's northern pinnacle reef trend (NPRT). Our methodology is based on capturing data on reservoir performance from reefs currently undergoing CO2‐EOR operations in the NPRT (referred to as ‘monitored reefs’), and then applying them to other reefs within the NPRT (referred to as ‘catalog reefs’). For each monitored reef, we calculate fractional primary recovery, fractional incremental EOR recovery, net utilization ratio, and storage efficiency factor. The corresponding incremental oil recovery from EOR, storage capacity until end of EOR, and total CO2 injection needs are then estimated for each catalog reef and combined (over all monitored reefs) using a weighted averaging procedure. These weights are related to a statistical similarity measure that is calculated between each monitored reef and each catalog reef based on a number of variables related to production data, formation type, or descriptive geologic attributes. For the entire NPRT catalog of 383 reefs as used in this study, our results indicate 118 million (MM) stock tank barrels (STB) (1.88 × 107 Sm3) of incremental oil from EOR operations, corresponding to 49 MM metric tons (MT) of CO2 storage and 266 MM MT of total CO2 injection. However, approximately one‐third of the reefs provide two‐thirds of the potential for CO2‐EOR and geologic storage, assuming an economic threshold of 0.5 MM STB (80 000 Sm3) of incremental oil from EOR. © 2020 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons, Ltd.