Acta Petrolei Sinica ›› 2015, Vol. 36 ›› Issue (10): 1210-1220.DOI: 10.7623/syxb201510004

• Petroleum Exploration • Previous Articles     Next Articles

Characteristics of analcime-dolomite reservoir from Shahejie Formation in Well Tang10 block of Dagang oilfield

Li Le1,2, Yao Guangqing1,2, Liu Yonghe3, Hou Xiuchuan4, Gao Yujie1,2, Zhao Yao1,2, Wang Gang1,2   

  1. 1. Key Laboratory of Tectonics & Petroleum Resources of the Ministry of Education, China University of Geosciences, Hubei Wuhan 430074, China;
    2. Faculty of Earth Resources, China University of Geosciences, Hubei Wuhan 430074, China;
    3. The 4th Oil Production Plant, PetroChina Dagang Oilfield Company, Tianjin 300280, China;
    4. Oil and Gas Evaluation Division, PetroChina Dagang Oilfield Company, Tianjin 300280, China
  • Received:2015-03-06 Revised:2015-07-06 Online:2015-10-25 Published:2015-11-09

大港油田塘10井区沙河街组方沸石白云岩储层特征

李乐1,2, 姚光庆1,2, 刘永河3, 侯秀川4, 高玉洁1,2, 赵耀1,2, 王刚1,2   

  1. 1. 中国地质大学构造与油气教育部重点实验室 湖北武汉 430074;
    2. 中国地质大学资源学院 湖北武汉 430074;
    3. 中国石油大港油田公司第四采油厂 天津 300280;
    4. 中国石油大港油田油气藏评价事业部 天津 300280
  • 通讯作者: 姚光庆,男,1964年12月生,1985获武汉地质学院学士学位,1999年获中国地质大学(武汉)博士学位,现为中国地质大学(武汉)资源学院教授、博士生导师,主要从事储层地质学教学及相关研究工作。Email:gqyao@cug.edu.cn
  • 作者简介:李乐,男,1985年8月生,2009年获西南石油大学学士学位,现为中国地质大学(武汉)博士研究生,主要从事储层地质及元素地球化学方面研究工作。Email:Santali2005@gmail.com
  • 基金资助:

    中国石油大港油田公司重点项目"塘沽地区沙三5特殊岩性体沉积特征及油藏综合评价"(DGYT-2012-JS-566)资助。

Abstract:

Analcime-dolomite reservoir from Shahejie Formation in Well Tang10 block of Dagang oilfield is a kind of unconventional reservoir, which is characterized with unique mineral composition and fracture. This paper tried to summarize the general characteristics of this kind of reservoir and discuss the control factors of reservoir quality, using data from thin section observation, X-ray diffraction analysis, scanning electron microscope analysis, physical property analysis, high-pressure mercury porosimetry, and nitrogen adsorption analysis. The rock mainly comprises ankerite, analcime, quartz, feldspar, and illite. It is common to find that lamina associations are presented in laminated dolomite and laminated argillaceous dolomite,including analcime-rich lamina+ankerite-lamina, silt-rich lamina+ankerite-lamina, analcime-rich lamina+algae lamina+ankerite-rich lamina, and mud-rich lamina+ankerite-rich lamina association. Vug and fracture are two types of macroscopic pores, while vug in analcime-fillings, intercrystalline pore, intracrystalline pore, and micro fracture are dominantly microscopic pores. Average porosity is 12.73% for dolomite and 10.39% for argillaceous dolomite; average permeability is 0.009 3mD for dolomite and 0.143 7mD for argillaceous dolomite. There is no distinct link between porosity and permeability. The reservoir share the feature of fine pore and throat diameter as well as complicated connection. Average pore volume is 20.45 mm3/g for dolomite and 23.46 mm3/g for argillaceous dolomite; average micro-mega pore ratio is 38.32% for dolomite and 55.7% for argillaceous dolomite; average surface-volume ratio is 0.83×107/m for dolomite and 0.932 5×107/m for argillaceous dolomite; average threshold pressure is 4.68 MPa; average median pore diameter is 0.047 μm; average tortuosity is 83.681; average maximum pore diameter is 0.279 μm. Further analysis showed that: (1)the rocks with black organic grain texture can get porosity increased by about 2%~6%; (2) micro-mega pore predominate in reservoir space; (3) the increase of carbonate content will decrease the porosity; (4) clay minerals, quartz and feldspar have positive relation with macro pore. With these evidences at hand, we concluded that the intracrystalline pore in diagenetic analcime is the dominant reservoir space of the rocks and the sedimentary layer containing black organic grain will enhance the porosity, which make the sedimentation and diagenesis the major control factors of porosity. The diagenetic and tectonic factors were considered to be the major control factors of permeability for the following reasons: the permeability is chiefly controlled by fine diameter of pore and throat as well as complex relation between pore and throat. Microfracture, though improved the permeability also, have only limited effect.

Key words: analcime, intracrystalline pore, dolomite, Shahejie Formation, Tanggu area

摘要:

大港油田塘10井区沙河街组湖相方沸石白云岩储层是一类矿物组成独特且裂缝广泛发育的低孔致密非常规储层。基于研究区塘12C井的岩心、岩石薄片、X射线衍射矿物分析、扫描电镜、物性分析、高压压汞分析及氮气低温吸附分析等基础资料,笔者试图从岩石矿物、储集空间、物性及孔喉特征等方面对该类储层的基本特征进行归纳并探讨储层受控因素。研究表明:储层岩石主要由铁白云石、方沸石、石英、长石及伊利石几类矿物组成,纹层极为发育,可划分出"富方沸石纹层+富铁白云石纹层""富粉砂纹层+富铁白云石纹层""富方沸石纹层+藻纹层+富铁白云石纹层"及"富泥纹层+富铁白云石纹层"等几类组合。岩石宏观储集空间包括溶孔及裂缝两大类,微观储集空间中则见方沸石充填溶蚀孔、晶间孔、晶内孔及微裂缝几类。白云岩平均孔隙度12.73%,渗透率平均为0.009 3 mD。泥质白云岩孔隙度平均10.39%,渗透率平均0.143 7 mD。孔隙度与渗透率之间无明显联系。储层孔隙结构具有孔喉半径细小、孔喉结构复杂的特征,其中,白云岩孔容平均为20.45 mm3/g,微孔—介孔率平均为38.32%,表面积/体积比平均为0.83×107m-1,排驱压力平均为4.68 MPa,中位孔径平均为0.047 μm,曲折度平均83.681,最大孔径平均0.279 μm。泥质白云岩孔容平均为23.46 mm3/g,微孔—介孔率平均为55.7%,表面积/体积比平均为0.932 5×107m-1。进一步研究发现,测试岩样所赋存的黑色有机质颗粒层结构能带来2% ~6% 的孔隙度增量,因而认为该结构为促使孔隙度增高的一大因素;氮气低温吸附及高压压汞联用资料表明两类岩性中的储集空间以微孔—介孔级(<50 nm)孔隙为主,此外,目的层碳酸盐矿物含量增加会引起孔隙度降低,黏土矿物及石英长石碎屑含量亦主要与大孔(>50 nm)具良好相关性。结合镜下观察到的孔隙类型,研究认为微孔—介孔级别孔隙主要由方沸石一类矿物提供,即:方沸石中所赋存的晶内孔是储层的主要储集空间。因此,目的层段储层孔隙性主要受控于沉积+成岩因素。微裂缝的发育对储层渗透性有一定的改善,但改善效果有限,孔隙及喉道极细的半径及复杂的空间配置关系对储层渗透率起到主要控制作用,亦即成岩+构造因素影响储层渗透性。

关键词: 方沸石, 晶内孔, 白云岩, 沙河街组, 塘沽地区

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