In this paper, solvent bubble nucleation and liberation processes in the heavy crude oil−CO₂ systems, heavy crude oil−CH₄ systems and heavy crude oil−C₃H₈ systems were experimentally studied and theoretically analyzed. First, two respective series of tests were conducted for different heavy crude oil−solvent systems. The first series included eleven conventional isothermal constant-composition-expansion (CCE) tests and the other series consisted of three new isothermal constant-composition-expansion & compression (CCEC) tests. Second, the amount of the evolved gas (i.e., the dispersed gas and free gas) in each pressure reduction step was determined from the measured CCE test data to study the solvent bubble nucleation process in each heavy crude oil−solvent system. A new quantity named the bubble nucleation index (BNI) was introduced and used to represent the solvent bubble nucleation strength. Third, the respective amounts of the dispersed gas and free gas in each pressure reduction step were obtained from the measured CCEC test data to examine the solvent bubble liberation processes in three heavy crude oil−solvent systems. A second new quantity named the bubble liberation index (BLI) was defined and applied to represent the solvent bubble liberation strength. It was found from the CCE and CCEC tests that the measured P_cell−v_t data for each heavy crude oil−solvent system had three distinct regions. Region I was the one-phase region. Region II was the foamy-oil region, in which the solvent bubble nucleation started and the solvent bubbles were dispersed in the heavy oil. Region III was the two-phase region, in which the free-gas phase was formed and started to dominate the total compressibility of the heavy crude oil−solvent system. In addition, the solvent supersaturation vs. reduced pressure data indicated that the heavy crude oil−CH₄ system had the lowest solvent supersaturation at the same reduced pressure in comparison with the heavy crude oil−CO₂ or C₃H₈ system. Thus CH₄ was easier to be nucleated from the heavy oil in comparison with CO₂ or C₃H₈. Moreover, the BNI vs. solvent supersaturation data showed that the BNI of the heavy crude oil−CH₄ or C₃H₈ system was slowly increased at lower solvent supersaturations but quickly increased at higher solvent supersaturations, whereas the BNI of the heavy crude oil−CO₂ system was almost linearly increased with solvent supersaturation. Furthermore, the BLI vs. reduced pressure data revealed that in comparison with C₃H₈/CO₂, CH₄ was the most difficult solvent to be liberated from the heavy oil once its bubbles were nucleated. A large amount of CH₄ bubbles could be trapped in the heavy oil to induce the strongest and most stable foamy oil in comparison with C₃H₈ and CO₂. The above experimental findings help to better understand the foamy-oil strengths and stabilities in different heavy crude oil−solvent systems and determine the most suitable solvent to optimize a solvent-based enhanced oil recovery (EOR) process in a heavy oil reservoir.

本文研究了重质原油-CO ₂体系、重质原油-CH ₄体系和重质原油-C ₃ H _{8体系中溶剂气泡的成核和释放过程。}系统进行了实验研究和理论分析。首先，针对不同的重质原油-溶剂系统分别进行了两个系列的测试。第一个系列包括 11 项常规等温恒组成膨胀 (CCE) 测试，另一个系列包括三个新的等温恒组成膨胀和压缩 (CCEC) 测试。其次，根据测量的 CCE 测试数据确定每个减压步骤中的逸出气体量（即分散气体和游离气体），以研究每个重质原油-溶剂系统中的溶剂气泡成核过程。引入了一个名为气泡成核指数（BNI）的新量，用于表示溶剂气泡成核强度。第三，从测量的CCEC测试数据中获得每个减压步骤中分散气体和游离气体的各自量，以检查三个重质原油-溶剂系统中的溶剂气泡释放过程。定义了第二个新量，称为气泡释放指数 (BLI)，并用于表示溶剂气泡释放强度。从 CCE 和 CCEC 测试中发现，测量的每个重质原油-溶剂系统的P_单元- v _{t数据具有三个不同的区域。}区域 I 是单相区域。II 区为泡沫油区，此时溶剂气泡开始形核，溶剂气泡分散在稠油中。区域 III 是两相区域，其中形成了游离气相，并开始主导重质原油-溶剂体系的总可压缩性。此外，溶剂过饱和与减压数据表明，与重质原油-CO ₂或C ₃ H ₈体系相比，在相同减压条件下，重质原油-CH ₄体系的溶剂过饱和度最低。因此 CH_{与CO 2}或C ₃ H _{8相比， 4}更容易从重油中成核。此外，BNI vs. 溶剂过饱和度数据表明，重质原油-CH ₄或 C ₃ H ₈体系的 BNI 在较低的溶剂过饱和度下缓慢增加，但在较高的溶剂过饱和度下迅速增加，而重质原油的 BNI -CO ₂体系随着溶剂过饱和几乎线性增加。此外，BLI 与减压数据显示，与 C ₃ H ₈ /CO ₂相比，CH ₄一旦重油的气泡形成核，它是最难从重油中释放出来的溶剂。_{与C 3} H ₈和CO ₂相比，大量CH ₄气泡可以被困在稠油中，形成最强和最稳定的泡沫油。上述实验结果有助于更好地了解不同稠油-溶剂体系中的泡沫油强度和稳定性，并确定最合适的溶剂以优化稠油油藏中的溶剂型提高采收率 (EOR) 工艺。