Improved Performance and Prediction For In Situ Combustion

Sanjay Srinivasan

Public Abstract

This proposal seeks to increase oil recovery by in situ combustion in both heavy-oil and light-oil reservoirs. Currently, in situ combustion is limited to steeply dipping, homogeneous reservoirs. Application is further limited by the lack of a reliable model for the process that can be used in process design. The proposed research will investigate the application of foam to prevent gas channeling and thereby extend in situ combustion to a wider class of reservoirs.

In addition, an improved model for representing the propagation of the combustion front in all reservoirs will be developed. The improved model could be used to study field-scale application of in situ combustion in heavy- and light-oil reservoirs. In all these ways, the research will focus on increasing oil recovery by in situ combustion, increasing the range of reservoirs to which in situ combustion can be applied and improving the accuracy of process performance prediction.

In situ combustion (ISC) is an efficient means of oil recovery for heavy and light oil reservoirs in homogeneous reservoirs when operated under gravity-stable conditions. In heterogeneous reservoirs, and without gravity-stable conditions, the combustion front rapidly advances either at the top of the reservoir or through high-permeability zones. Foam has been demonstrated to counteract the adverse effects of heterogeneous permeability distributions and gravity segregation. This proposal seeks to investigate the feasibility of foam injection to improve vertical conformance and thereby extend in situ combustion to heterogeneous reservoirs. Data from the literature on foam at high temperatures will be incorporated into a simulation model that will be used to test the feasibility of foam in conjunction with ISC. The goal is to seek improvements in the design, test the range of reservoir descriptions and foam properties for which the process can be effective, and thereby guide future process development.

Current numerical simulators are inadequate for modeling in situ combustion processes at the field scale. Laboratory data measured on combustion tube tests cannot generally be used directly for modeling field-scale processes, because numerical dispersion in the computer models distorts behavior in the model. In order to overcome these shortcomings, a new algorithm for modeling propagation of flame fronts in reservoirs is proposed. The injection of foam will alter the flow profile of air to the flame front, which in turn will impact mass transfer at and ahead of the combustion front and the reaction kinetics. An integrated model is proposed to capture the interactions between these different processes.

This research would be sponsored by the Department of Energy.


Contact:

Sanjay Srinivasan
Center for Petroleum and Geosystems Engineering
1 University Station C0304
The University of Texas at Austin
Austin, Texas 78712-0228
Phone: (512) 471-7218 FAX: (512) 471-9605
Email: ssriniva@mail.utexas.edu