Full field production profile is needed to evaluate enhanced oil recovery (EOR) option and to progress the EOR project. In general, the methodology of full-field profile estimation highly depends on the objective case: field development maturity level, technology readiness level of the EOR option to be planned, etc. Therefore, this paper is facilitating how we should select an adequate methodology to estimate full-field EOR profiles through comparison of four case studies.
Case-1 was picked up as an example of type curve method based on sector models for water alternating gas (WAG) application using CO2 or hydrocarbon miscible gas. Case-2 represented a full-field simulation approach to incorporate facility capacities into account adequately because of produced gas re-injection (i.e. gas EOR). Case-3 demonstrated to use the identical flow model, which was history-matched with long production records, for estimating a new CO2 foam EOR technology which was unavailable as option in the identical commercial simulator. The last Case-4 dealt an emerging microbial EOR/EGR process without any commercial simulator and no pilot data yet.
In Case-1, two type curves were generated to represent typical geologies in the objective field: homogeneous and heterogeneous areas. After sensitivity studies using the simple sector models to optimize each parameter, type curves were obtained from the detailed sector models. The type curves, assigned in corresponding areas, were summed to estimate full-field profile. In Case-2, even full-field simulation is debatable in general due to huge workload and computation, it still has important role to evaluate gas EOR with limited gas processing capacity because to ignore the facility limits might mislead to optimistic conclusion. In Case-3 in the mature field, the history-matched model was already established by a commercial simulator. Unfortunately, the simulator does not have an exact option to evaluate our emerging CO2 foam technology while available for the conventional foam EOR using surfactant as foaming agent. Thus, we managed to handle our EOR technology by matching laboratory experimental outputs with pseudo-calculated gas mobility reduction ratio. In Case-4, another emerging microbial EOR technique was estimated analytically even only laboratory experimental data was available. Any commercial simulator is not available, either. The unique approach took essence of experimental outputs into a well type curve, and then full-field profile was estimated.
Each workflow has pros/cons, and an adequate one should be selected. However, in usual, a unique workflow is just applied to estimate full-field profile in the evaluation of objective EOR option. Furthermore, there has been little discussion of workflow selections from the aspect of development stage, EOR technological emerging level, and evaluation tool availability. This paper can provide ideas to consider guidelines for generating full-field profiles.