Evaluating Performance and Energy Efficiency of Hybrid Cyclic Steam Stimulation Technologies with a Novel Experimental Setup

An experimental program has been designed and executed to evaluate the performance of hybrid Cyclic Steam Stimulation (CSS) recovery methods. The overarching goal is to improve the energy efficiency and reduce the carbon footprint of CSS in Colombian heavy oil fields. Specifically, this work compares the impact that adding solvent or flue gas to cyclic steam injection has on the recovery of a recombined heavy live oil at a laboratory scale. A novel experimental setup was designed to evaluate hybrid CSS methods, which allows displacement of fluids out of the core during injection cycles and the return of those fluids to the core during soaking and production periods, by the use of a ballast system. A CSS baseline test and two hybrid CSS tests were performed at reservoir conditions (RC) with recombined live oil and core material from a Colombian heavy oil field. Each test consisted of four cycles with the same amount of steam injection. The hybrid CSS tests consisted of a steam-solvent and a steam-flue gas hybrid test. The CSS baseline and the hybrid CSS tests were successfully performed in the core pack with the injection of 0.12 pore volume CWE (Cold Water Equivalent) of steam per cycle, at core pressure near 680 psig and an initial core temperature of 45°C. In addition, steam-solvent and steam-flue gas hybrid tests injected near 0.01 and 0.05 PV (CWE) of solvent and flue gas per cycle, respectively. The steam front location during each cycle was identified with temperature profiles recorded along the core during the tests. Core pressures and fluid volumes displaced to and from the ballast were also recorded. Post-test core analyses allowed to estimate residual liquid saturations after each test. The addition of solvent or flue gas did not hinder the CSS oil recovery process which was in the order of 40% for all tests. The recovery, energy efficiency and carbon footprint of the hybrid CSS tests are compared to the CSS baseline case. Although a small amount of hydrogen sulphide (H2S) was detected at the end of the CSS baseline test, H2S was not detected in the produced gas of the hybrid tests. The experimental program enhanced the understanding of hybrid steam cyclic methods and the impact of solvent and flue gas addition on the recovery, energy efficiency and carbon footprint reduction of heavy oil CSS recovery processes. These results assist in the quest of improving CSS performance and provide key data for tuning numerical models. This novel experimental apparatus is one of a kind as it captures the cyclic nature of fluid movement during CSS.