This talk will highlight a forecasting approach that has proven effective in modeling the performance of West Texas CO2 projects. The presented methodology has been used to model the performance of the Wasson Denver Unit, which is the world’s largest miscible CO2 project. The primary use of the program has been for CO2 flooding; however, the same methods can be used for other tertiary processes such as alkaline surfactant flooding.
The approach has been implemented in a computer program that is based upon dimensionless recovery curves that can be either simulation-based or derived from analog project performance. One key attribute of the program is the ability to model the changes in reservoir processing rate that are common in these projects. Predictions are generated for all injected and produced fluids (oil, hydrocarbon gas, NGL yield, water, and CO2).
The program has also proven valuable as a surveillance tool for comparing actual versus predicted performance of an EOR project at the pattern level. Such analysis has identified project areas with good performance that are worthy of larger injected CO2 slugs, and also patterns within projects that are not meeting tertiary recovery targets.
The presentation will include the methodology employed in the program and will demonstrate, with examples from the Permian Basin, how this approach can be used to generate forecasts for field-scale EOR projects. Examples highlighting surveillance applications are also be included.