Comparison of alternate technologies to improve cyclic steam stimulation through numerical simulation

Abstract

Cyclic steam stimulation (CSS), is the most applied thermal enhanced oil recovery (EOR) method worldwide. However, despite the vast experience gained over the last few decades CSS still have its challenges including but not limited to energy efficiency and operational costs. CSS has been evaluated for several years in Colombian heavy oil reservoirs. With CCS 

approaching its maturity new alternatives and injection strategies are required to potentially extend the technical-economical limit of this recovery process. Therefore, this work is focused on the evaluation of different strategies to potentially improve CCS performance. Alternate methods evaluated range from steam generation with solar energy to well heating strategies and CCS combined with flue gas, foams, solvents and nano particles (hybrid CCS methods). This evaluation was carried out using a semi-conceptual numerical simulation model representative of a Colombian heavy oil reservoir currently under CCS. The performance of hybrid CCS methods were compared against cold production, conventional CSS (base case) and heating well technologies. Furthermore, this paper summarizes the visualization of steam generation technologies through solar energy and some relevant field applications. Downhole heating technologies (i.e. electro-resistive heating, electro-inductive heating or steam recirculation) were evaluated using the “heater well” option. On the other hand, the hybrid CCS methods evaluated considered specific parameters and injection schedules for each technology to represent as much as possible the performance documented in the literature including some field applications. Based on the DNI (Direct Normal Irradiance), some regions of Colombia are candidates to consider steam generation based on solar energy. Despite the cost and environmental benefits, high CAPEX and the requirement of large acreage were some of the constraints identified. Regarding the simulation study, preliminary results of this study suggest that heating technologies showed greater performance in new wells and before CCS start (Pre-heating approach at initial reservoir pressure). Regarding the hybrid CSS methods, the efficiency of each of the technologies evaluated strongly depends on the reservoir conditions (CCS maturity) at the time it is implemented. Specifically, CCS combined with solvents or nano particles showed better performances at early stages of CSS (i.e. 2nd steam cycle). On the contrary, CCS combined with foams and flue gas evidenced better efficiencies when implemented at later stages of CSS (i.e. 6th steam cycle). Despite the potential identified in some of the technologies evaluated develop detailed experimental and simulation studies are strongly recommended. Finally, the approach followed in this study represents a reasonable screening methodology to preliminary support decision-making strategies of technical teams and managers identifying most promising technologies based on the resources available and current conditions of Colombian heavy oil reservoirs.