Lu Chang, Zhou Wenteng, Wang Chuanwei, Lin Riyi, Zhang Yingnan
Key Lab of Industrial Fluid Energy Conservation and Pollution Control, Ministry of Education, Qingdao University of Technology, Oingdao, 266520, People's Republic of China.
School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, 266520, People's Republic of China.
Sci Rep. 2025 Jan 29;15(1):3601. doi: 10.1038/s41598-025-88004-5.
Accurately predicting the phase behavior and properties of reservoir fluid plays an essential role in the simulation of petroleum recovery processes. Similar to the inaccurate liquid-density prediction issue in the isobaric-isothermal (PT) phase equilibrium calculations, an inaccurate pressure prediction issue can also be observed in isothermal-isochoric (VT) phase equilibrium calculations which involves a liquid phase. In this work, a practical methodology is proposed to incorporate a volume-translated equation of state in VT phase equilibrium calculations for more accurate pressure predictions. For this purpose, we adopt the state-of-art volume translation model recently proposed by Abudour et al. (Fluid Phase Equilib 349:37-55 2012, Fluid Phase Equilib 349:37-55, 2013). Single liquid phase calculations for 18 compounds and two hydrocarbon mixtures are conducted to demonstrate the soundness of the proposed methodology and evaluate the accuracy of pressure predictions. The calculated pressures by VT calculations with volume translated PR-EOS are compared to the actual pressures. The calculation results demonstrate that, by incorporating Abudour et al. (2012, 2013) volume translated PR-EOS models into the VT-based phase equilibrium calculation algorithm, the accuracy of pressure prediction in the single liquid phase region for both pure substances and mixtures can be significantly improved. Lastly, we apply the proposed algorithm to the two-phase VT phase equilibrium calculations for a ten-component oil sample MY10 which contains only normal alkanes. We numerically correct the pressure by applying the Abudour et al. VTPR-EOS to both the liquid phase and vapor phase. The pressures calculated by different phases become different. The pressures predicted based on the liquid phase are shifted downwards significantly, which leads to more accurate pressure predictions. To our knowledge, this issue is rarely investigated to incorporate the volume translation concept in VT phase equilibrium calculations.
准确预测油藏流体的相行为和性质在石油采收过程模拟中起着至关重要的作用。与等压 - 等温（PT）相平衡计算中液体密度预测不准确的问题类似，在涉及液相的等温 - 等容（VT）相平衡计算中也会出现压力预测不准确的问题。在这项工作中，提出了一种实用方法，即在VT相平衡计算中纳入体积平移状态方程，以实现更准确的压力预测。为此，我们采用了Abudour等人最近提出的先进体积平移模型（《流体相平衡》349:37 - 55，2012年；《流体相平衡》349:37 - 55，2013年）。对18种化合物和两种烃类混合物进行了单液相计算，以证明所提出方法的合理性，并评估压力预测的准确性。将采用体积平移PR - EOS的VT计算得到的压力与实际压力进行比较。计算结果表明，通过将Abudour等人（2012年，2013年）的体积平移PR - EOS模型纳入基于VT的相平衡计算算法中，纯物质和混合物在单液相区域的压力预测准确性都可以得到显著提高。最后，我们将所提出的算法应用于仅含正构烷烃的十组分油样MY10的两相VT相平衡计算。我们通过对液相和气相都应用Abudour等人的VTPR - EOS对压力进行数值校正。不同相计算得到的压力变得不同。基于液相预测的压力显著向下偏移，从而实现更准确的压力预测。据我们所知，很少有人研究在VT相平衡计算中纳入体积平移概念这一问题。
