大民屯凹陷西部古近系地层特征及成藏要素分析

发布时间：2018-08-09 13:07

【摘要】：大民屯凹陷是辽河盆地的重要油气富集区带之一。勘探实践表明,大民屯凹陷西部油气富集规律与古近系地层展布特征联系紧密。因此,为了进一步揭示大民屯凹陷西部油气分布规律,提高大民屯凹陷油气勘探成功率,本文从实际地质资料出发,对大民屯凹陷西部古近系地层进行了详细的划分,并以单井测井资料为基础建立连井地层剖面进行地层对比,揭示了大民屯凹陷西部古近系地层的分布规律;在此基础上,采用油源对比、沉积相分析及声波测井等技术方法分别对大民屯凹陷油气成藏条件展开研究,并讨论了大明屯古近系地层划分与油气生成运移和聚集的关系。大民屯凹陷古近系地层可以分为房身泡组、沙河街组和东营组三个组,属陆相河湖沉积环境,其中沙河街组沙四段、沙三段是该凹陷中重要含油气层段。进一步研究表明,大民屯凹西部古近系可划分为两个层序,层序Ⅰ包括沙四段和沙三段,层序Ⅱ包括沙一段和东营组。具体而言,沙四段和沙三段主要以湖侵体系域和高位体系域沉积为主。Es34亚段主要为一套砂泥频繁互层沉积,砂岩横向广泛分布。Es33亚段、Es32亚段、Es31亚段均发育砂砾岩、细砂岩与泥岩的不等厚互层沉积。但受沉积环境的控制,南北地区砂岩与泥岩含量差异较大,北部地区砂岩含量高,而南部地区主要为厚层的泥质沉积,砂岩发育程度较低。对比体系域与油气藏的烃源岩、储层和盖层的分布可知,烃源岩主要为湖侵体系域沉积;储集层砂体主要沉积于高位体系域下部的,主要为冲积扇—扇三角洲—滨浅湖沉积和曲流河—三角洲—滨浅湖沉积。湖侵体系域发育的烃源岩构成了古生界潜山油气藏的区域盖层,此外上部高位体系域的底部也形成了另一套区域性盖层。高蜡油系统对应的烃源岩体系中砂体含量低,而且上覆Es41厚层泥岩,从而导致其最主要的油气输导方式有两种:(1)源岩→潜山;(2)源岩→断层→Es3砂层。正常油系统对应的烃源岩体系中砂泥岩互层的特征明显,烃源岩生成的油气可以直接进入砂层或者通过断层、裂隙进行短距离运移进入砂层,然后继续运移聚集成藏。
[Abstract]:Damingtun depression is one of the important oil and gas accumulation zones in Liaohe Basin. The exploration practice shows that the oil and gas enrichment in the western part of Damingtun depression is closely related to the distribution characteristics of Paleogene strata. Therefore, in order to further reveal the distribution of oil and gas in the western part of Damingtun Sag and improve the success rate of oil and gas exploration in Damingtun Sag, the Paleogene strata in the western part of Damingtun Sag are classified in detail based on the actual geological data. On the basis of single well logging data, the formation profile of multiple wells is established for stratigraphic correlation, which reveals the distribution law of Paleogene strata in the western part of Damingtun Sag, on the basis of which oil source correlation is used. Sedimentary facies analysis and acoustic logging are used to study the oil and gas accumulation conditions in Damingtun sag, and the relationship between the division of Paleogene strata and the generation, migration and accumulation of oil and gas is discussed. The Paleogene strata in Damingtun depression can be divided into three groups: Fangshengpao formation, Shahejie formation and Dongying formation, belonging to the continental fluvial and lacustrine sedimentary environment, among which the Shahejie formation is the fourth member of the Shahejie formation, and the third member of the Shahejie formation is an important oil-bearing gas reservoir in the sag. Further study shows that the Paleogene in the western part of Damingtun depression can be divided into two sequences: sequence I includes the fourth and third member of Sha, and sequence II includes the first member of Sha 1 and the formation of Dongying. In particular, the lacustrine transgressive system tracts and highstand system tracts are the main depositions of the fourth and third member of Sha, which are mainly composed of a set of sand and mud frequent interbedded deposits, and the sandstones are developed in the sandstones in the transverse distribution of the sandstones in the es 32 submember of the es 32 submember, which is widely distributed in the sandstones. Interbedded deposits of fine sandstone and mudstone with unequal thickness. However, controlled by sedimentary environment, the content of sandstone and mudstone varies greatly in the north and south, and the sandstone content is high in the north, while in the south, it is mainly a thick layer of argillaceous deposit, and the development degree of the sandstone is relatively low. The distribution of source rocks, reservoirs and caprocks in system tracts and reservoirs shows that the source rocks are mainly lacustrine transgressive system tracts, and the reservoir sandbodies are mainly deposited in the lower part of high system tracts. It is mainly alluvial fan-fan delta-shore shallow lake deposit and meandering river-delta-shore shallow lake deposit. The source rocks developed in the lacustrine transgressive system tracts constitute the regional caprocks of the Paleozoic buried hill reservoirs, in addition, another set of regional caprocks are formed at the bottom of the upper system tract. The sandbody content in the source rock system corresponding to the high-waxy oil system is low, and the Es41 thick mudstone is overlying, which leads to two main modes of oil and gas transportation: (1) source rock and buried hill; (2) source rock / fault / Es3 sand layer. The characteristics of sandstone and mudstone interbedded in the corresponding source rock system of normal oil system are obvious. The oil and gas generated by source rock can enter directly into sand layer or through fault, and fissures can migrate into sand layer for short distance, and then continue to migrate and accumulate to form reservoir.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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