Water Alternative Gas Process Optimizing for CO₂-EOR and Carbon Storage

Abstract

Carbon capture, utilization and geological storage (CCUS) is a promising way to reduce the emissions of the anthropogenic CO₂ into the atmosphere. Sequestering the CO₂ into depleted hydrocarbon reservoirs is the most achievable approach under current economic constraints, which not only increases the recovery of existing oil reserves but also bridges the gap between regional-scale CCUG. The Upper Devonian fluvial sandstone reservoirs in Jacksonburg-Stringtown oil field in West Virginia is an ideal candidate for CO₂ sequestration coupled with EOR, which have produced over 22 million barrels of oil since 1895. This work illustrates an example of CCUS, in which CO₂ is simultaneously sequestered and oil recovery enhanced in a depleted oil reservoir by water alternating gas (WAG) method. Three mechanisms for CO₂ storage including structural/stratigraphic trapping, dissolution trapping, and residual trapping are considered. This model is based on a highly detailed geological model constructed based on existing legacy geological data from the field. A composition model of 0.4 PVI of water injected before WAG process is considered as a benchmark for this study. The results of numerical simulation show that over 26 years of WAG injection, oil recovery increased from 0.16\% to 1.9\% due to various injection strategies. WAG injection rate, injection time ratio and cycle period play important roles in the storage CO₂. As a conclusion, this research constructs and validates a basic workflow for CO₂ storage and CO₂-EOR that can be applied to other super-mature oil fields, which have abundant conventional legacy data and limited high-quality data.

AAPG Datapages/Search and Discovery Article #90350 © 2019 AAPG Annual Convention and Exhibition, San Antonio, Texas, May 19-22, 2019