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

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