Enhanced Oil Recovery in a High Stratigraphic Complex Reservoir: Casabe Project Case Study

Abstract

Casabe field reservoir characteristics are multilayer, geological complexity, vertical/areal heterogeneity and commingled production. Due large difference in mobility between oil and water (M ~ 20) and the maturity of water flooding, several operational problems have arisen, such as, increase of water cut, channeling, sand production, etc. These problems together with the high remaining reserves and identification of bypassed oil, were the main reasons to evaluate EOR process as a solution to increase the recovery factor. A reduced Cycle Time was created to reduce the time from design to full field implementation which involves the following phases: Screening/Conceptual Design, Pilot Design, Drilling-Workover and Facilities, Operation & Surveillance, Pilot Expansion, Full Field Development Plan, Reserves & FID. This strategy is based on multitask parallel process to allow fast track decision making and activities execution for a fast pilot implementation, which allowed to implement the EOR pilot in 24 months form the screening to pilot Operation & Surveillance. After the screening, polymer flooding was considered for mobility ratio modification to improve sweep efficiency and therefore increase RF. The best producer layers were selected, based on the areal continuity and residual oil in place, as target sands for polymer injection. One pattern was selected for the pilot. Laboratory tests, along with reservoir simulation confirmed the potential of chemical EOR in the selected sands and pilot area. Polymer injection was performed in four injector wells of the selected pattern. The polymer flooding process was monitored in the central producer and in the eight producers of the second line. A surveillance plan was implemented to collect the information required to evaluate, with the lowest uncertainty, the results of this pilot. An observation well was drilled to monitored changes in oil saturation. The surveillance plan was critical to be able to control the polymer injection process, to have a proper technical evaluation of the pilot and to optimize costs during the future expansion and full field implementation. Polymer flooding have increased the RF on the selected area. The fast-tracking strategy for an EOR project execution was successfully implemented in Casabe Field and the pilot was delivered in 2 years proving the concept of 5-year road map it is possible. The reduced Cycle Time (5-year Road Map) could be used as reference for implementation of new EOR pilots in other fields in shorter time and optimizing resources. The workflows used and the analysis procedures created for this pilot could be used as reference for the implementation of future pilots in fields with similar characteristics.

Optimizing Well Completion for Polymer Flooding in Conjunction with Waterflood Flow Control Valves

“…Based on the results obtained and following the findings of Gheneim et al (2017) [45], the following injection parameters are recommended:…”

Strategy for Optimum Chemical Enhanced Oil Recovery Field Operation

“…Graham and Frigo 2019 discussed other challenges related to the operations, such as corrosion, souring, emulsion, scaling, injectivity decline, and induced-fracture extension that all need to be modelled. Goudarzi et al 2016 performed a benchmark study of available reservoir simulators for CEOR and compared different processes for UTCHEM, CMG, and Eclipse-E100 (based on versions available in 2016). Table 4 gives a summary of the comparative study.…”

“…A summary of the benchmark study of different reservoir simulators. FromGoudarzi et al (2016). , capillary pressure, the effect of pH on surfactant adsorption, etc.…”