Browsing by Author "Wang, Qiong"

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    Cold, Hot and Steam Assistant Solvent Injection Processes for Heavy Oil Recovery
    (2018-06-26) Wang, Qiong; Chen, Zhangxing (John); Abedi, Jalal; Pereira Almao, Pedro R.
    Solvent-based processes such as vapor extraction (VAPEX) can be another technology that has potential to enhance heavy oil recovery in a more cost-efficient and environment friendly way. Extensive experimental and simulation studies have been conducted to evaluate VAPEX. However, theoretical modeling has not gained much progress in the past two decades. This thesis aims at adopting a series of mathematical models for a new theoretical analysis of comprehensively evaluating solvent-based recovery processes and also attempts to develop a new process to enhance production. This thesis first develops a comprehensive theoretical analysis method for VAPEX, which considers all the major recovery mechanisms such as dynamic mass transfer, gravity drainage, multiphase flow, and boundary movement in the model. Both constant and variable diffusivity have been studied in this model, and the latter justified in the progressive change of properties such as viscosity in the media within the diffusion layer. A hot solvent injection process takes advantages of both thermal recovery processes (quick heat conduction and large viscosity reduction) and solvent-based processes (lower energy consumption and less green-house gas emission). This thesis then develops a transient mass transfer model to analyze the cold heavy oil–hot solvent mixing process during a hot solvent injection process. This mass transfer model is then incorporated into the VAPEX model to evaluate the performance of a hot solvent injection process. Key indicators such as oil production profile, injection pressure, injection temperature, solvent oil ratio, etc. have been studied to find out a quantitatively correlation. A new hybrid process, SAVE, is proposed to enhance heavy oil recovery. In this process, a short-slug steam and a long-slug solvent are alternately injected to extract heavy oil. Simulation results show that the cumulative steam-oil ratio of SAVE is 37.26% of that of SAGD. In comparison with VAPEX, SAVE produces oil 8.4 times faster than VAPEX and its cumulative solvent-oil ratio of SAVE is only 26% of that of VAPEX. SAVE performs relatively better in thinner formations than in thicker ones.