Browsing by Author "Li, Yishu"

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Open Access
Investigating the role of water and nanoparticles in the performance of CO2 and ethane-based cyclic solvent injection process for heavy oil recovery
(Faculty of Graduate Studies and Research, University of Regina, 2024-04) Li, Yishu; Zeng, Fanhua (Bill); Gu, Yongan (Peter); Jia, Na (Jenna); Du, Zhongwei (David); Qing, Hairuo; Zhang, Yin
Cyclic solvent injection (CSI) process is a promising method for enhancing heavy oil recovery in thin or deep heavy oil reservoirs. Foamy oil flow is a major phenomenon of the CSI process, but the impact of foam stabilizers like nanoparticle and water on its performance has not been well understood. Therefore, an in-depth understanding of waterflooding and nanoparticle affecting CSI performance is a crucial step toward further enhancing oil recovery. In addition, most studies only focus on one method. In fact, in order to develop an oil reservoir cost-effectively and efficiently, a variety of methods have to be applied in sequence. In this study, a well-designed experimental investigation was conducted to determine the role of water and nanoparticle in CSI process. First, several foundemental live oil depletion tests were applied to investigate the feasibility of using foamy oil additives in the CSI process, determine the optimum concentration of the additives, and evaluate the best operation conditions on the performance of the CO2 based CSI process. Second, three CO2 based CSI tests were performed using a cylindrical sandpack at different injection pressure. Test 1 conducted a normal CO2 based CSI process for comparison. Test 2 applied a waterflooding process and followed by a CO2 based CSI process. Test 3 was a hybrid process consisting of the sequence: CSI-waterflooding-CSI-Nanoparticle solution flooding- CSI. Third, two ethane based CSI tests (A blank test and a similar combination test) were applied in order to verify and compare CO2 based CSI process. Experimental parameters and results were monitored and recorded. Comprehensive data analytics were performed to examine the effect of water and nanoparticle and identify enhancing mechanisms for the CSI process. Experiment results indicate that using nanoparticles as foam stabilizers in CO2 live oil pressure depletion tests can enhance oil recovery while reducing gas recovery, with higher nanoparticle concentrations resulting in even greater oil recovery. An optimal depletion rate of 6 kPa/min was identified, and the waterflooding process had a positive impact on the performance of both CO2 and ethane based CSI methods, improving mass transfer by expanding gas/oil contact areas. The nanoparticle solution flooding applied before CSI process were able to effectively stabilize foamy oil even at high water saturation levels. The integration of CSI, water flooding, and nanoparticle solution flooding yields an overall oil recovery factor of 69.5% for the combined CO2 based hybrid EOR process and 76.1% for the ethane based hybrid EOR process. Simulation results show that the dispersed gas model exhibits strong alignment between oil and gas production data and pressure distribution in CO2 based live oil pressure depletion tests. For CO2 based CSI process, by incorporating a modified foamy oil model with separate sets of relative permeability curves for injection and production stages, and employing the dispersed gas model during production stage, a robust history-matching of oil, gas, and water production data is achieved simultaneously. In the Lloydminster area, thousands of wells have a water cut exceeding 90% after the waterflooding process and are subsequently abandoned due to the absence of an effective way to continue development. This study meticulously examines potential enhancements for the CSI process, which involve utilizing foam stabilizers in combination with synergistic water flooding methods. The findings of this study provide practical solutions to address the technical challenges encountered during the subsequent development of heavy oil wells with high initial water saturation. Additionally, the study highlights the promising prospects of combination approaches in enhancing heavy oil recovery.
Open Access
Pretreatment of Oilfield Produced Water using Ionic Liquids for Dissolved Air Floatation
(Faculty of Graduate Studies and Research, University of Regina, 2017-03) Li, Yishu; Henni, Amr; Zeng, Fanhua; Ismail, Mohamed; Shirif, Ezeddin
Energy consumption is rising due to population increase and industry development. There will be an increase of nearly 66% of energy consumption related to fossil fuel such as oil and gas between 2003 and 2030 from 7.6*1013 to 12.6*1013 kilowatt-hours worldwide. With the increase in the production of oil and gas, a larger amount of produced water (PW) will be generated. Produced water poses a risk to the environment, because it contains persistent toxic and carcinogenic constituents. The dissolved air floatation (DAF) process is the most widely used technique in the world for produced water treatment. In order to reach better experimental results, different coagulants are added as a pretreatment process. In this research, as a pretreatment to the DAF process, three similarly structured ionic liquids (n-methylpyridinium tosylate, 1,3-dimethylimidazolium tosylate, and 1-benzyl-3-methylimidazolium tosylate) were used to improve the efficiency of treatment. An orthogonal experimental design (OED) with different factors and levels was designed to determine the most effective ionic liquid, the best operation conditions, and the influence strength order of different factors. Two blank columns were designed for error estimate. Range analysis and variance analysis (ANOVA) were used to understand factor influence and determine the best operating conditions. The results of the experiments indicate that, with the same operation conditions (concentration, speed, and reflux ratio), 1-benzyl-3-methylimidazolium tosylate had the highest oil and turbidity removal efficiency when compared to the other two ionic liquids. According to range analysis and variance analysis (ANOVA), the three ionic liquids have the same influential order for the three factors considered with an ionic liquid concentration influence greater than that of both speed (RPM) and the reflux ratio (RR). The best operating conditions for the three ionic liquids were 300 mg/l for ionic liquid concentration, 200 for RPM, and 20% for RR, respectively. At the best operating conditions, the percentages of the removal of oil content were 75.4% ± 0.7% for n-methylpyridinium tosylate, 71.0% ± 0.2% for 1,3-dimethylimidazolium tosylate, and 81.6% ± 0.3% for 1-benzyl-3-methylimidazolium tosylate, respectively.