吕建荣,丁振华,张德富,王晓光,聂振荣
Lü Jianrong,DING Zhenhua,ZHANG Defu,WANG Xiaoguang,NIE Zhenrong

• 1:中国石油新疆油田分公司勘探开发研究院

摘要(Abstract)：

为了准确计算页岩油气储层中的界面张力,基于修正的Soave-Redlich-Kwong状态方程(SRK EoS)和修正的van der Waals(vdW)混合规则,建立一个预测纳米孔中油气界面张力的状态方程模型,该模型能描述纳米孔中孔隙半径和分子—分子间相互作用的影响。将状态方程与等张比容模型结合,建立基于气液相平衡的界面张力计算模型,并提出具体计算方法。建立的SRK模型与vdW模型和实验数据对比表明:在相同的温度下,随着压力的升高,甲烷-正葵烷(C_1-nC_(10))和氮气-正葵烷(N_2-nC_(10))混合物在纳米孔中的界面张力逐渐减小,SRK和vdW模型均能准确地预测界面张力,但SRK模型的计算结果更准确。在298.15 K和326.15 K,SRK模型计算的C_1-nC_(10)混合物的平均绝对相对偏差为12.42%和7.11%,而N_2-nC_(10)混合物为2.83%和3.85%。vdW模型计算的C_1-nC_(10)混合物的平均绝对相对偏差为17.10%和4.24%,而N_2-nC_(10)混合物为3.98%和7.53%。通过SRK模型对体积相和纳米孔中的界面张力预测表明:在相同的温度压力条件下,体积相中的C_1-nC_(10)和N_2-nC_(10)混合物界面张力大于纳米孔中的界面张力。对不同孔隙半径的纳米孔中的界面张力预测表明:随着孔隙半径的减小,混合物的界面张力逐渐减小,且在较低的压力下,孔隙半径越小,界面张力的减小程度越大,而在较高的压力下,由于界面张力比较小,孔隙半径的影响也较小。提出的SRK模型能准确地预测纳米孔中的界面张力,为预测纳米孔中油气界面张力提供了一种新思路。
To accurately calculate the interfacial tension in shale oil and gas reservoirs, the model of the state equation was established for the interfacial tension of oil/gas in nanopores based on the modified Soave-Redlich-Kwong equation of state(SRK EoS) and the modified van der Waals(vdW) mixing rule, and it can characterize the influences of the pore sizes and molecule-molecule interactions. Combining the equation of state with the parachor model, the IFT calculating model was constructed based on the vapor-liquid equilibrium, and the specific calculating method was presented. Comparisons between SRK/vdW model and the experimental data show that the interfacial tensions of the methane-n-decane(C_1-nC_(10)) and nitrogen-n-decane(N_1-nC_(10)) mixtures in nanopores gradually decrease with the pressure increase at the same temperature. Both of the models can accurately predict the interfacial tensions, but the SRK model is more accurate. At 298.15 K and 326.15 K, the average absolute and relative deviations of the C_1-nC_(10) mixtures calculated by SRK model are 12.42% and 7.11%, while those of N_1-nC_(10) mixtures are 2.83% and 3.85% respectively. The average absolute and relative deviations of C_1-nC_(10) mixtures calculated by vdW model are 17.10% and 4.24%, while those of N_2-nC_(10) mixtures are 3.98% and 7.53% respectively. With the help of SRK model, the IFT predictions in the volume phase and the nanopores indicate that the interfacial tensions of C_1-nC_(10) and N_2-nC_(10) mixtures in the volume phase are much larger than those in the nanopores under the same temperature and pressure conditions. The predictions of the interfacial tension of different pore radii in the nanopores show that the mixture interfacial tensions decline with the decrease of the pore radii; the smaller the pore radius under low pressure, the greater the decrease degree of the interfacial tension is. However, due to the relatively small interfacial tension under high pressure, the influence of the pore radius is less too. The presented SRK model can accurately predict the interfacial tension in nanopores, which provides a new idea to predict the oil-gas interfacial tension in nanopores.

关键词(KeyWords)： 纳米孔;界面张力;气液平衡;状态方程;混合规则
nanopores;interfacial tension(IFT);vapor-liquid equilibrium;equation of state(EoS);mixing rule

Abstract:

Keywords:

基金项目(Foundation): 中国石油重大科技专项“新疆油田已开发水驱油藏二三结合提高采收率技术研究与应用”(2017E-04-06);; 新疆维吾尔自治区天山青年计划“砾岩油藏二元驱分级动用实验评价及理论研究”(2020Q103)

作者(Author): 吕建荣,丁振华,张德富,王晓光,聂振荣
Lü Jianrong,DING Zhenhua,ZHANG Defu,WANG Xiaoguang,NIE Zhenrong

DOI: 10.19597/j.issn.1000-3754.202009002

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