Journal of Petroleum & Environmental Biotechnology

Experimental investigation of the extent to which different concentrations of C3H8, CH4 and CO2 affect CSI performance

3^rd International Conference and Expo on Oil and Gas

July 13-14, 2017 Berlin, Germany

Farshid Torabi and Arash Ahadi

University of Regina, Canada

Posters & Accepted Abstracts: J Pet Environ Biotechnol

Abstract:

Cyclic Solvent Injection (CSI) technique holds great promise as a viable approach to produce heavy oil from thin reservoirs where thermal and gravity-dominated recovery methods fail to produce oil. CO2 and C3H8 (due to their high solubility) are the main solvents that have been used in CSI. However, CO2 is not always accessible and it causes corrosion problems during implementation. In addition, low saturation pressure of C3H8 limits the application of pure C3H8 for heavy oil extraction. On the other hand, CH4 is widely accessible and has high saturation pressure. In this study, different concentrations of C3H8 in CH4 stream (i.e., 15, 30, and 50 mole %) are tested. A sandpack model with porosity and permeability of 32.4% and 9.7 d, and a heavy crude oil with viscosity of 6430 mPa.s are used to represent a typical thin heavy oil formation. First, different ratios of C3H8 to CH4 stream are examined to quantify the optimum solvent concentration. Second, CO2 is introduced to the optimum CH4-C3H8 concentration to investigate the extent to which CSI behavior changes by partially replacement of CH4 with CO2. Results show that ultimate recovery factor (RF) increases from 24.3% to 33.4% original oil in place (OOIP) when C3H8 concentration increases from 15 to 50 mole% in the CH4 stream. CSI tests with higher C3H8 concentration reaches the maximum cyclic recovery with lower number of injection cycles due to higher solubility of C3H8 compared with CH4. Solvent utilization factor (SUF) data also confirms this as lesser volume of solvent with higher C3H8 concentration is required to produce oil. Virtual observations also shows that the foamy oil produced during the process lasts longer with higher concentration of C3H8 (2 min for 85% CH4-15% C3H8 case and 180 min for 50% CH4-50% C3H8 case). Upon addition of CO2 to the mixture, the oil production is slightly improved as the ultimate RF increases to 35.9% OOIP. The produced foamy oil also lasts for 197 min for 50% C3H8-35% CH4-15% CO2 case. In general and for all cases, the solvent oil ratio (SOR) increases with cycle numbers, specifically during the last two cycles, highlighting that large portion of the injected solvent is produced instead of diffusing into the oil phase.

Biography :

Email: farshid.torabi@uregina.ca