Reid B. Grigg

Improved Efficiency of Miscible CO2 Floods and Enhanced Prospects for CO2 Flooding Heterogeneous Reservoirs

The goal of this project is to improve the efficiency of miscible CO2 floods and enhance the prospects for flooding heterogeneous reservoirs. This report provides results of the second year of the three-year project that will be exploring three principles: (1) Fluid and matrix interactions (understanding the problems). (2) Conformance control/sweep efficiency (solving the problems. 3) Reservoir simulation for improved oil recovery (predicting results).The goal of this project is to improve the efficiency of miscible CO2 floods and enhance the prospects for flooding heterogeneous reservoirs. This report provides results of the second year of the three-year project that will be exploring three principles: (1) Fluid and matrix interactions (understanding the problems). (2) Conformance control/sweep efficiency (solving the problems. 3) Reservoir simulation for improved oil recovery (predicting results).

Wellman unit CO2 flood : Reservoir pressure reduction and flooding the water/oil transition zone

CO 2 injection is a proven technology. Results from two decades of reservoir and economic performance prove that CO 2 can 1) be transported over large distances via pipeline 2) handled and injected easily at well-site facilities and 3) recover oil that water injection could not mobilize. This has been accomplished at cost levels which are profitable provided enough HCPV (hydrocarbon pore volume) of CO 2 is injected in the reservoir and sweep and displacement efficiency arc sufficient. The most recent challenge involves optimizing efficiency of CO 2 flooding, i.e. maximizing oil recovery hile at the same time reducing operating expenses. A useful method to attain the goal of CO 2 flood optimization is careful performance review of better performing CO 2 floods. The Wellman Unit CO 2 flood has a long history. This CO 2 flood is one of the most successful CO 2 floods documented in terms of CO 2 utilization, i.e. MCF of CO 2 required to recover one barrel of oil. This paper explorcs the role of laboratory experimentation for improvement of performance of a maturc CO2 flood. In this paper, we will review the history of the Wellman Unit CO 2 flood and examine two possibilitics to optimizc reservoir performance: 1) Reducing CO 2 injection pressure thereby reducing the volume of purchased CO 2 while at the same time maintaining miscibility (optimum displacement efficiency) and 2) Exploring the possibility of mobilizing reserves in the water-oil transition zone below thc origina oil-water contact.

Improveed Efficiency of Miscible CO(2) Floods and Enhanced Prospects for CO(2) Flooding Heterogeneous Reservoirs.

A new grant, `Improved Efficiency of Miscible C0{sub 2} Floods and Enhanced Prospects for C0{sub 2} Flooding Heterogeneous Reservoirs`, DOE Contract No. DE-FG26-97BC 15047, has been awarded and started on June 1, 1997. This work will examine three major areas in which C0{sub 2} flooding can be improved: fluid and matrix interactions, conformance control/sweep efficiency, and reservoir simulation for improved oil recovery.

Validation and Comparison of Carbon Sequestration Project Cost Models with Project Cost Data Obtained from the Southwest Partnership

Obtaining formal quotes and engineering conceptual designs for carbon dioxide (CO{sub 2}) sequestration sites and facilities is costly and time-consuming. Frequently, when looking at potential locations, managers, engineers and scientists are confronted with multiple options, but do not have the expertise or the information required to quickly obtain a general estimate of what the costs will be without employing an engineering firm. Several models for carbon compression, transport and/or injection have been published that are designed to aid in determining the cost of sequestration projects. A number of these models are used in this study, including models by J. Ogden, MITs Carbon Capture and Sequestration Technologies Program Model, the Environmental Protection Agency and others. This report uses the information and data available from several projects either completed, in progress, or conceptualized by the Southwest Regional Carbon Sequestration Partnership on Carbon Sequestration (SWP) to determine the best approach to estimate a projects cost. The data presented highlights calculated versus actual costs. This data is compared to the results obtained by applying several models for each of the individual projects with actual cost. It also offers methods to systematically apply the models to future projects of a similar scale. Last, the cost risks associated with a project of this scope are discussed, along with ways that have been and could be used to mitigate these risks.

Improving CO2 Efficiency for Recovering Oil in Heterogeneous Reservoirs

The work strived to improve industry understanding of CO2 flooding mechanisms with the ultimate goal of economically recovering more of the U.S. oil reserves. The principle interests are in the related fields of mobility control and injectivity.

Improved efficiency of miscible CO{sub 2} floods and enhanced prospects for CO{sub 2} flooding heterogeneous reservoirs

This project examines three major areas in which CO{sub 2} flooding can be improved: fluid and matrix interactions, conformance control, sweep efficiency, and reservoir simulation for improved oil recovery. This report discusses the activity during the calendar quarter covering October 1, 1999 through December 31, 1999 that covers mostly the second fiscal quarter of the projects third year. Injectivity experiments were performed on two Indian limestone cores. In tests on the first core, a variety of brine, CO{sub 2} WAG, and oil contaminant injection schemes indicated infectivity reduction due to phase conditions and contamination. The results are only quantitative because of plugging and erosion in the core. To date, tests on the second core have investigated the effects of long-term brine stability on the reduction of fluid-rock interaction, in order to quantify fluid effects on infectivity. The authors continue to develop a new approach in reservoir simulation to improve the history matching process on clusters of PCs. The main objective was to improve simulation of complex improved oil recovery methods, such as CO{sub 2}-foam for mobility control and sweep enhancements. Adsorption experiments using circulation and flow-through methods were used to determine the loss of surfactants for economic evaluation. A sacrificial agent, lignosulfonate, was used to reduce the adsorption of the primary foaming agent in both Berea sandstone and Indian limestone. The lignosulfonate has also shown a chromatograph effect, advancing more rapidly through the reservoir, thus initially adsorbing onto the rock before the primary foaming agent arrives. Therefore, considering the simplicity of operation and economics of reducing the cost of expensive surfactant to improve oil recovery, coinjection of lignosulfonate with the primary foaming agent might be a practical approach to consider for field application.

Improved Efficiency of Miscible CO{sub 2} Floods and Enhanced Prospects for CO{sub 2} Flooding Heterogeneous Reservoirs

This work will examine three major areas in which CO{sub 2} flooding can be improved: fluid and matrix interactions, conformance control/sweep efficiency, and reservoir simulation for improved oil recovery. The first full quarter of this project has been completed. We began examining synergistic affects of mixed surfactant versus single surfactant systems to enhance the properties of foams used for improving oil recovery in CO{sub 2} floods. The purpose is to reduce the concentration of surfactants or finding less expensive surfactants. Also, we are examining the effect of oil saturation on the development of foam in CO{sub 2}-surfactant solution systems. CO{sub 2} flooding of low permeability, vugular, and fracture reservoirs are another major thrust of this project. Work conducted this quarter involved simulating gravity stable floods using large core samples; results showed excellent recovery in a low permeability vugular core.

Improved Efficiency of Miscible C02 Floods and Enhanced Prospects for C02 Flooding Heterogeneous Reservoirs

Surfactant and foam properties have been evaluated at high pressure using the foam durability apparatus. For a number of surfactant solutions the interfacial tension with cense CO2, critical micelle concentrations, foaming ability, and foam stability were determined. Preliminary results show that these tests correlate well to predict surfactant properties and mobility in cores. Work has also restarted in the parallel-dual permeability system.