07123-03

Primary Performer
University of Kansas Center for Research, Lawrence, KS 66045

Additional Participants
Carmen Schmitt, Inc., Great Bend, KS 67530

Abstract
Carbon dioxide (CO₂) injection for enhanced oil recovery is a proven technology. It is also considered as one of the most promising methods for carbon sequestration in geologic formations. CO₂ injections are normally operated at a pressure above the minimum miscibility pressure (MMP), which is determined by crude oil composition and reservoir conditions. However, many reservoirs in the United States and around the world are at shallow depths or geologic conditions exist such that they operate at pressures below the MMP. The goal of this project is to demonstrate near miscible CO₂ application can substantially increase oil productions with CO₂ injection at pressures below MMP. The application of CO₂ injection at near miscible conditions may lead to development of CO₂ projects for small producers in reservoirs where the MMP is not attainable at current operating reservoir pressures.

When CO₂ injection operates at a pressure below the MMP, displacement efficiency decreases as a result of the loss of miscibility. Near miscible displacement generally refers to the process occurring at displacement pressures below the MMP, but the actual pressure range has never been clearly defined. At displacement pressures near miscible, significant oil recovery has been observed in slim-tube experiments and to a lesser extent in core tests. This better recovery has been attributed to possible improvement of the mobility ratio in the displacement and an extraction process, both of which are closely related to operating pressure. To increase the resource base for CO₂ flooding and substantially increase the production from reservoirs operated by small producers, it is proposed to investigate the feasibility of applying CO₂ displacement at near miscible pressures by conducting appropriate experimental work and reservoir simulation.

The proposed project will include both experimental and computational studies. In the experimental study, proposed work will 1) systematically characterize the near miscible condition and study recovery of waterflood residual oil using CO₂ displacement at near miscible pressures, and 2) identify key parameters in phase behavior and flow tests for simulation modeling. In the computational study, the proposed work will 1) develop a representative model to simulate near miscible displacement physics and 2) assess the potential of recovery processes at near miscible pressures.

This project is a joint effort by the Tertiary Oil Recovery Project (TORP) at the University of Kansas and Carmen Schmitt, Inc. (Kansas independent producer). The successful completion of this feasibility study will lead to future field demonstration pilots in producing areas operated by our project partner in the Arbuckle formation. The potential benefits will be significant with an increase in the resource base for CO₂ flooding and an expanded opportunity for small producers to apply CO₂ flooding.

Principal Investigators: Jyun Syung Tsau