准噶尔盆地吉木萨尔凹陷芦草沟组致密油形成条件与分布规律

利用准噶尔盆地吉木萨尔凹陷芦草沟组地质、试油、录井、岩石薄片及地球化学等资料，研究了致密油的形成条件、分布特征及其控制因素。研究区致密油形成条件优越，烃源岩有机质丰度高、有机质类型为Ⅰ和Ⅱ型并且为低熟-成熟阶段；储层岩性复杂，甜点段平面连续性好，孔隙类型多样；广泛分布的烃源岩与储层频繁互层，烃源岩生成的油气直接进入相邻储层，有利于致密油的富集；芦草沟组超压广泛发育，是致密油运移的主要动力。致密油纵向上分布受优质烃源岩控制，全段均见油气显示，主要富集于优质烃源岩层附近的储层中；平面上受烃源岩有机质丰度、烃源岩厚度及储层厚度的综合控制，主要分布于烃源岩厚度大于200 m、TOC高于35%、储层厚度大于15 m的区域之内

Formation and Distribution of Tight Oil of Permian Lucaogou Formation in the Jimsar Sag of Junggar Basin,Northwestern China

Based on the data sets of geology, oil production test, logging, rock thin section and geochemistry of Permian Lucaogou Formation (LCG) in the Jimsar Sag of Junggar Basin, we studied the formation and distribution of tight oil. LCG source rocks are excellent level with high total organic carbon and Ⅰ, Ⅱ type kerogens, containing low mature to mature organic matter. The sweet spot sections are large in total thickness, good in continuity, with a variety of lithology. The source rocks and tight reservoirs are widely distributed and form an optimal source reservoir caprock combination through space and time, which are beneficial to tight oil accumulation. The abnormal overpressure in LCG provided a drive force for tight oil migration and charging. The excellent level source rocks, reservoirs, optimal source reservoir caprock combination, and abnormal overpressure are key factors to tight oil formation. There is oil show in the whole LCG and the tight oil is mainly accumulated in reservoirs related to excellent level source rocks in vertical. The tight oil is mainly distributed in the areas with thick source rocks (>200 m), high TOC (>35%) and thick reservoirs (>15 m), and controlled by source rocks and reservoirs in plane.