甘谷驿油田张罗沟区块长6储层油藏描述

发布时间：2019-06-04 21:04

【摘要】：甘谷驿油田位于陕西省延安市宝塔区与延长县交界处,构造位置位于鄂尔多斯盆地次级构造单元—陕北斜坡的东南部,区域地质活动较弱,三叠系延长组长6油层组是该油田最重要的含油层系。其长6储层总体表现为矿物成熟度低、结构成熟度较高,且所形成的油藏具有低孔、低渗、低含油饱和度的特点。前人对甘谷驿油田其他区域的沉积相及油藏特征研究较多,但对于张罗沟区的科研工作相对较薄弱,基础地质研究程度低。因此,对该区的沉积项和储层特征进行深入研究,可为该区的储量计算及编制开发方案提供依据。本文在区域地层对比基础上,结合钻、测井等资料对延长组长6油层组进行小层精细划分,为顶面构造特征分析、沉积相展布以及油藏分析等提供准确的地层研究单元。研究表明,长6油层组各小层顶面构造形态整体表现为西倾斜坡,构造倾角不到1°,平均坡降3-4m/km,且在中西部的唐231～唐176井区发育一个形态完整的北东-南西走向的背斜构造,各小层之间的构造形态具有较强继承性。通过张罗沟区沉积微相研究显示,长6油层组沉积体系类型为一套水退背景下建设型三角洲前缘沉积,微相类型以水下分流河道及分流间湾为主。水下分流河道为油气富集提供了有利的储集空间,分流间湾泥岩及粉砂质泥岩既可作为油气侧向遮挡,也可作为直接盖层,为研究区长6油藏的油气富集提供很好的遮挡和保存条件。长6储层砂岩岩石类型为长石砂岩,碎屑颗粒磨圆度以次圆～次棱角状为主,分选程度为中～好,物性条件相对较差,属低～特低孔、特低～超低渗储层,但各小层之间的储层物性相差不大,总体受沉积和砂体展布控制,孔隙度、渗透率分布区间相对较均匀,在一定的压裂条件下,可以改善物性条件,仍可获得很好的产能。结合甘谷驿油田的储层划分标准,综合评价认为张罗沟区长6储层类型为Ⅱ、Ⅲ类,具备一定的储集能力,为有效储层,属中等～较好类别储层。延长组成熟的烃源岩、长6油层组三角洲前缘复合河道砂体、叠置连片砂层及微裂隙形成的有利通道、岩性圈闭形成时期与有利排烃期的有机配置等因素的共同作用,使甘谷驿油田张罗沟区具备了有利的油气成藏条件,油藏类型为岩性油藏,油水混储,无明显边、底水,其分布主要受水下分流河道砂体物性控制,油藏埋深总体为东浅西深。
[Abstract]:Ganguyi Oilfield is located at the junction of Baota District and Yanchang County, Yan'an City, Shaanxi Province. the tectonic position is located in the southeast of the secondary tectonic unit of Ordos Basin-the northern slope of Shaanxi, and the regional geological activity is weak. The Yanchang 6 formation of Triassic is the most important reservoir-bearing system in this oil field. The Chang6 reservoir is characterized by low mineral maturity and high structural maturity, and the reservoir has the characteristics of low porosity, low permeability and low oil saturation. There are many previous studies on sedimentary facies and reservoir characteristics in other areas of Ganguyi Oilfield, but the scientific research work in Zhangluogou area is relatively weak and the degree of basic geological research is low. Therefore, the in-depth study of sedimentary items and reservoir characteristics in this area can provide the basis for the calculation of reserves and the compilation and development of reserves in this area. On the basis of regional formation correlation, combined with drilling and logging data, the small layer fine division of Yanchang 6 reservoir group is carried out in this paper, which provides an accurate formation research unit for the analysis of top structural characteristics, sedimentary phase distribution and reservoir analysis. The results show that the structural morphology of the top surface of each small layer of Chang6 reservoir is westward inclined slope, with a structural dip angle of less than 1 掳and an average slope drop of 3-4 m 鈮，

本文编号：2493000