Evaluation of Future CO2 Injection in Denver City Field for Enhanced Oil Recovery and CO2 Storage

Abstract

Abstract Operating companies are finding that mature oil fields close to CO2 pipeline and processing infrastructure may offer an attractive option for enhanced oil recovery with improved returns aided by 45Q CO2 storage incentives. This case study evaluates future EOR and CCUS scenarios for the Denver City field in West Texas. Forecasts consider multiple options ranging from requiring little to no capital (more injection into existing patterns) to significant investment including the additional drilling of project expansion wells to prospective pattern areas. The evaluation of the Denver City field with more than 50 wells penetrating a 50 ft oil column and 240 ft of residual oil zone included the historically active 1000-acre area includes surrounding area expanding evaluation considerations to about 5200 Ac for monitoring the area of potential CO2 influence. Analog Wasson Field information filled data gaps. Inter-well connectivity models suggested well constraints and identified workover opportunities. These analyses supported forecast assumptions made for continuous injection and WAG scenarios. Mature field areas with past CO2 injection for EOR purposes are contrasted with new patterns available for CCUS. Out of the nine active inverted 5-spot patterns, six mature southern patterns offer diminishing EOR returns from additional CO2 injection. Converting adjacent waterflood patterns to continuous CO2 injection followed by water alternating gas (WAG) provides the best enhanced oil recovery (EOR) and CO2 storage value with less recycle volumes. Depending on the level of incentive provided to the EOR project, additional drilling may be warranted to extend oil recovery on the edges of the field and maximize the CO2 storage into additional available pore space. Dimensionless modeling provided forecasts for various options while 45Q incentives are active. A low investment case injecting significantly more CO2 into existing CO2 patterns showed poor performance and efficiency. Horizontal wells added to the project may improve near term cashflow while providing future wells that can be used as in the CCUS project as injection wells or maintained as producing wells. Performance to date shows improved oil recovery from both main oil column and the residual oil zone due to CO2 injection. Based on these results, short-term and long -term recommendations address long-term CO2 storage volumes as well as expansion considerations. 45Q tax incentives for CCUS projects provide support for marginal mature field use for carbon capture projects. Maximizing short term oil production and CO2 retention while minimizing gas recycling may alter the priorities of conventional CO2 EOR flooding. Oil field anticlines provide excellent candidates for CCUS projects.