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致密油已成为国内外油气勘探的热点领域之一,其储层物性是寻找、评价致密油“甜点”的重要依据。运用岩芯观察、薄片分析、扫描电镜和压汞分析等手段,分析了准噶尔盆地吉木萨尔凹陷芦草沟组致密油储层物性特征和储层物性的主要影响因素。结果表明,芦草沟组致密油储层为典型的致密油储层,上甜点段物性略优于下甜点段。储层孔隙类型主要为各类溶蚀孔隙、微裂缝和剩余粒间孔隙,其中又以晶间(粒间)溶蚀孔隙为主,微米级——纳米级微孔隙十分发育。储层具有孔喉细小,形态复杂,分选性和连通性差,且分布不均匀等孔隙结构特征,孔隙结构和微裂缝发育情况对渗透率影响较大,导致孔隙度与渗透率相关性不明显。影响储层物性的主要因素为成岩作用和微裂缝发育情况,压实作用是导致储层致密的根本原因,溶蚀作用是后期形成次生孔隙的主要因素,沉积作用和胶结作用对储层物性影响较小,微裂缝对储层整体物性的改善作用较为有限。
Tight oil has become one of the hottest fields of oil and gas exploration at home and abroad. Its reservoir physical properties are the important basis for finding and evaluating the tight oil “sweet spot ”. By means of core observation, slice analysis, scanning electron microscopy and mercury intrusion analysis, the main influencing factors of physical properties and reservoir physical properties of the Lucaogou Formation tight oil reservoir in the Jimusar area in the Junggar Basin are analyzed. The results show that the tight oil reservoirs in Lucaogou Formation are typical tight oil reservoirs, and the physical properties of the upper desserts are slightly better than those of the lower desserts. The pore types of the reservoirs are mainly all kinds of dissolved pores, micro-cracks and remaining intergranular pores, of which intergranular (intergranular) dissolved pores are dominant and micro-scale and nano-scale micro-pores are well developed. The reservoirs have the characteristics of small pore throats, complex shapes, poor sorting and connectivity, uneven distribution and other pore structure characteristics. The development of pore structure and microcracks greatly affects the permeability, resulting in no obvious correlation between porosity and permeability . The main factors influencing reservoir physical properties are diagenesis and microcrack development. Compaction is the fundamental reason leading to the densification of reservoirs. Dissolution is the main factor for the formation of secondary pores in later stage. The effect of sedimentation and cementation on reservoir physical properties The effects of small and micro-cracks on the overall physical properties of reservoirs are limited.