定边地区延长组下部储层的沉积地质意义

陕西延长石油(集团)有限责任公司研究院,陕西 西安 710069

地质资源与地质工程; 沉积地质; 致密储层地质; 定边地区; 延长组下部

Sedimentary geological significance of reservoir in the Lower Member of Yanchang Formation in Dingbian Area
CAO Yue,LIU Yan-zhe,DUAN Xin-ting,FU Ming-yi,ZHANG Qing

(search Institute of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi'an 710069,China)

geological resources and geological engineering; sedimentary geological significance; tight reservoir geology; Dingbian Area; lower Member of Yanchang Formation

DOI: 10.13800/j.cnki.xakjdxxb.2018.0119

备注

为搞清定边地区延长组下部储层的沉积地质意义,应用致密储层地质学理论,研究了延长组下部长7-长9构造、烃源岩、沉积微相、砂体分布及储层岩石学等方面地质特征,并结合测试资料对储层的沉积地质意义进行了分析。研究表明:现今构造为西倾背景下的挠曲单斜,发育了4排鼻状隆起构造带; 长7烃源岩为延长组下部油藏的主要贡献者,分布于研究区西南部,厚度20~50 m; 发育了北西向、北东向2大物源控制的三角洲前缘水下分流河道微相,西南部2大水下分流河道微相交汇区域砂岩分布不均衡,厚度15~40 m,形成了各种类型砂岩透镜体、成岩圈闭、砂岩尖灭等岩性圈闭; 储层类型为近源高能沉积环境下的岩屑质长石砂岩,粒间孔发育,黏土矿物含量高,孔隙度平均值为8.4%,渗透率平均值为2.99 mD,表现为特低孔-特低渗储层。结果 表明:水下分流河道微相及其交汇区域的砂岩储层、鼻状隆起构造、烃源岩等因素的有效耦合,是油气富集成藏的关键因素,也是油气科技工作者今后重点关注与研究方向。

In order to clarify sedimentary geological significance of reservoir in the lower member of Yanchang Formation of the Upper Triassic in Dingbian Area,applying geological theory of tight reservoir,the geological characteristics of structure,source rock,sedimentary microfacies,sand body distribution and reservoir petrology of the Chang 7-Chang 9 in the lower member of Yanchang Formation was studied,and the sedimentary geological significance of the reservoir was analyzed based on the test data.The study shows that the present structure is a torsion zone monocline under the background of west dip,and four rows of nose uplift tectonic belts were developed; source rock of Chang7 is the main contributor to lower reservoir of Yanchang Formation,and it is distributed in the southwest of the study area,with a thickness of 20~50 m; the subaqueous distributary channel microfacies of the delta front of the Delta controlled by two major provenance from northwest and northeast are developed,the distribution of sandstone in the intersection of two large subaqueous distributary channel microfacies in the southwest is uneven with the thickness of 15~40 m,and the lithological traps of various types of sandstone lenses,diagenetic traps,sandstones pinchout,etc are formed; the reservoir type is the lithic feldspar sandstone in the near source and high energy sedimentary environment,intergranular pores are developed,content of clay minerals is high,the mean porosity is 8.4%,the mean permeability is 2.99 mD and the reservoir appears ultra-low porosity and ultra-low permeability.Results indicate that:Effective coupling of factors such as subaqueous distributary channel microfacies,sandstone reservoir,nose uplift tectonic belts and source rock in the intersection of subaqueous distributary channel microfacies is key factors for oil and gas accumulation,and is also the focus and direction of oil and gas science and technology workers in the future.