吉174井是准噶尔盆地吉木萨尔凹陷芦草沟组页岩油储层取心最长、资料最多的探井,其“铁柱子”的建立对于页岩油纵向特征的研究具有重要意义。研究发现：储层岩性以碎屑岩和碳酸岩混杂的过渡岩性为主,纵向变化快;岩相反映向上水体逐渐增深的半深—深湖相沉积环境;储层平均孔隙度为11.1 %,平均渗透率为0.056 ×10^-3μm²,属于中—低孔、低渗—特低渗储层;储层白云石和砂质含量与物性、含油性呈正相关;发育上、下2套甜点体,上“甜点”储集层岩性主要为砂屑云岩,发育溶蚀孔发育型储集空间,厚度为24 m;下“甜点”储集层岩性主要为粉细砂岩、云屑砂岩和云质粉砂岩,储集空间主要为裂缝—孔隙型,厚度35 m;2套甜点体有利区面积为1 299 km²,展现芦草沟组页岩油具备规模勘探潜力。

Well-Ji-174 is an exploration well with the longest core extraction and the most data in the shale oil reservoir of Lucaogou Formation in Jimusar sag, Junggar Basin. The establishment of the “iron pillar” is of great significance to the studies of the shale oil longitudinal characteristics. It is found that the lithology of reservoir is mainly transitional lithology mixed with clastic rock and carbonate rock, and changes quickly in the longitudinal direction. The lithofacies reflects the semi-deep to deep lacustrine sedimentary environment with gradually deepening upward water body. The average porosity and permeability of the reservoir are 11.1 % and 0.056×10^-3 μm², respectively, which make the reservoir presents the characteristics of medium-low porosity, low-permeability and ultra-low permeability. The dolomite and sand content of the reservoir are positively correlated with the physical property and oil content. The upper and lower sweet spots are developed. The main lithology of the upper sweet spot is clastic dolomite, allowing the formation of the reservoir space with developed dissolution pores and a thickness of 24 m. The main lithology of the lower one is fine siltstone, dolomite sandstone and dolomite siltstone, whose reservoir space with thickness of 35 m is mostly fissures and pores. The favorable area of these two sweet spots covers an area of 1 299 km², indicating that the shale oil in Lucaogou Formation has large-scale exploration potential.