Multi-Reservoir Fast-Track Evaluation of EOR Potential Using Conceptual Simulation Models. A Tool to Prioritize Future EOR Efforts
Authors: Suzanne G. , Nurseitova M. , Andjar K. , Garifullin R. , Lantoine M. , Roosz S. , Lemaux T. 
Published: February 2017

The objective of the approach presented here was to assess the applicability of EOR methods for 10 light-oil reservoirs in a short-time period (6 months). There were two goals in this study: Identify for each reservoir the most promising EOR method in terms of oil recovery and estimated large-scale economicsIdentify the most promising reservoir(s) on which further efforts on EOR development should be concentrated.

To meet these objectives, simplified numerical simulations were performed at well-pattern scale. Extracting and history-matching a sector from an existing model being too long for this study specific timeline, the following steps were adopted: Identification of typical well log and pattern geometryConstruction of a representative sector model (geometry and petrophysical properties)Dynamic calibration of the sectorSimulation of water-based and gas-based EOR processes with a multi-scenario approach scanning the main uncertain parametersUpscaling of the results (production and injection profiles) from the sector to the field scaleEconomic analysis to calculate usual indicators for each EOR scenario.

The methodology was successfully developed and applied to 10 light-oil reservoirs.

Up to 3 water-based or gas-based EOR methods were simulated per reservoir. Since thermal methods were discarded during a preliminary screening, they were not considered at this stage of the study. No laboratory analysis was performed during this study. For each EOR process, parameters were varied within their range of uncertainty in order to scan a wide range of possible scenarios. Consequently, around 50 scenarios were simulated for each EOR process and reservoir.

Scenarios giving promising results at the simulation scale were extrapolated to the field scale and yearly-based economic analysis was performed for each of them. This economic analysis used estimated CAPEX and OPEX, consistent with each reservoir conditions and extent. The outputs of this economic analysis were common indicators such as net present value and profitability index. These indicators were used to perform a ranking of the most economically promising EOR processes of 10 reservoirs.

Among these reservoirs, 3 were identified as very promising for chemical EOR application, and 1 for a gas-based method. As a result of this work more detailed feasibility studies, including laboratory work, are now considered for the most promising reservoirs.

Though the EOR simulations and the economic analysis techniques are not novel in this workflow, this advanced EOR screening approach is innovative since it provides economic indicators, in addition to the usual recovery factor, which helps prioritise reservoirs regarding their EOR potential. This methodology stands between analytical workflows which estimate recovery (usually without capturing geological heterogeneities nor providing economic indicators) and more detailed, time-consuming and more expensive workflows with large-scale reservoir simulations.