Abstract: After over a decade of efforts, significant breakthroughs have been achieved in exploitation and development of the Middle Permian Lucaogou Formation shale oil in Jimusaer sag of Junggar Basin, which is a typical representative of saline lacustrine shale oil in China. However, there is still less research on phase simulation and physical property prediction for Lucaogou Formation shale oil under reservoir temperature and pressure conditions, resulting in limited practical guidance from experimental thermal simulation results for actual exploration and production. Using the micro-scale sealed vessel thermal simulation system in combination with a variety of organic geochemical analysis methods, a systematic study has been performed on the hydrocarbon generation kinetics and hydrocarbon generation thermal simulation experiments of shales with different sedimentary sub-facies in Lucaogou Formation. Based on experimental data, the PhaseKinetics model was innovatively applied to reveal the phase evolution patterns and physical property characteristics of shale oil at different maturity stage. The results show as follow. (1) The Lucaogou Formation shale mainly generates high-wax paraffinic crude oil, and peak oil production occurs when the vitrinite reflectance (R_o) is approximately 1.3 %. (2) Under reservoir temperature and pressure conditions, the current thermal evolution degree (R_o ranging from 0.5 % to 1.2 %) of Lucaogou Formation shale oil corresponds to the typical pure oil reservoir with an extremely low gas-oil ratio. (3) The comparison between pressure-volume-temperature (PVT) simulation results and field production data indicate that under reservoir conditions, the predicted shale oil density is highly consistent with the measured data, revealing the oil density distribution of lower in the eastern and western areas and higher in the central area. The research results not only theoretically elaborate the phase evolution mechanisms of saline lacustrine shale oil, providing scientific evidences for fine exploration of shale oil in Lucaogou Formation of Jimusaer sag, but also form a series of prediction methods for predicting the phases and physical properties of shale oil under reservoir temperature and pressure conditions.

Key words: Junggar Basin, Lucaogou Formation, saline lacustrine shale, hydrocarbon generation model, phase simulation, physical property prediction of crude oil

摘要： 作为中国咸水湖相页岩油的典型代表,准噶尔盆地吉木萨尔凹陷中二叠统芦草沟组页岩油经过十余年勘探开发已实现重大突破。然而,目前针对该地区页岩油在储层温压条件下的相态模拟和物性参数预测研究仍显不足,导致实验热模拟结果难以有效指导实际生产开发。应用微型密闭玻璃管热模拟系统,结合多种有机地球化学分析技术,对芦草沟组不同沉积亚相页岩开展了系统的生烃动力学与热模拟实验研究。基于实验数据,创新性地应用相态动力学(PhaseKinetics)模型揭示了页岩油在不同成熟度阶段的相态演化规律及物性变化特征。研究结果表明:(1)芦草沟组页岩主要生成高蜡型-石蜡基油,其生油高峰在镜质体反射率(R_o)约为1.36%时出现;(2)在储层温压条件下,芦草沟组页岩油在现阶段的热演化程度(R_o为0.5%~1.2%)呈现典型的纯油藏特征,其气油比极低;(3)压力—体积—温度(PVT)模拟结果与现场生产数据对比表明,储层条件下的页岩油密度预测值与实测值高度吻合,揭示了吉木萨尔凹陷芦草沟组页岩油的原油密度具有“东西部低、中部高”的平面分布格局。该研究成果不仅从理论上阐明了咸水湖相页岩油的相态演化规律,为吉木萨尔凹陷芦草沟组页岩油的精细勘探提供了科学依据,同时也建立了一套适用于储层温压条件的页岩油相态-物性预测方法,为同类致密油藏的开发评价提供了可借鉴的技术范例。

关键词: 准噶尔盆地, 芦草沟组, 咸水湖相页岩, 生烃模式, 相态模拟, 原油物性预测