油气藏评价与开发 ›› 2020, Vol. 10 ›› Issue (4): 101-106.doi: 10.13809/j.cnki.cn32-1825/te.2020.04.016

• 常规油气 • 上一篇    下一篇

准噶尔盆地车拐斜坡区储层碳酸盐胶结物碳氧同位素特征及其成因

陈波1,2(),张顺存2,孙国强2,史基安2,吴涛3   

  1. 1.广西高校北部湾石油天然气资源有效利用重点实验室(北部湾大学),广西 钦州535000
    2.甘肃省油气资源研究重点实验室/中国科学院油气资源研究重点实验室,甘肃 兰州 730000
    3.中国石油新疆油田分公司勘探开发研究院,新疆 克拉玛依 834000
  • 收稿日期:2019-02-26 出版日期:2020-08-26 发布日期:2020-08-07
  • 作者简介:陈波(1985 —),男,博士,讲师,从事地球化学研究。通讯地址:广西钦州市滨海大道12号北部湾大学城,邮政编码:535000。E-mail:cbo- 11@163.com
  • 基金资助:
    广西自然科学基金联合资助培育项目“多因素耦合作用下砂泥岩互层间蒙脱石伊利石化形成机理及主控因素研究”(2019GXNSFAA245016)

Characteristics and formation mechanism of Carbonate cementation in Che-Guai slope area, Junggar Basin

CHEN Bo1,2(),ZHANG Shuncun2,SUN Guoqiang2,SHI Ji’an2,WU Tao3   

  1. 1.Guangxi Colleges and Universities Key Laboratory of Beibu Gulf Oil and Natural Gas Resource Effective Utilization, Beibu Gulf University, Qinzhou, Guangxi 535011, China
    2. Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, Gansu, China
    3. Research Institute of Exploration and Development, Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China
  • Received:2019-02-26 Online:2020-08-26 Published:2020-08-07

摘要:

阐明碳酸盐胶结物的形成机制及对储层物性的影响具有重要意义,综合通过岩矿学、地球化学方法,分析了准噶尔盆地车拐斜坡区储层碳酸盐胶结物的赋存特征及形成机制,结果表明:δ 13CPDB值为-29.6 ‰~6.7 ‰,δ 18OPDB值为-19.2 ‰~-12.5 ‰,跨度较大,说明碳酸盐胶结物形成的物质来源及水岩相互作用的复杂性。δ 13CPDBδ 18OPDB值分别较典型的海相或湖相的碳酸盐呈正偏移和负偏移,δ 13CPDB正偏移主要受到混合热液流体碳同位素分馏和少量沉积碳酸盐溶解的共同作用,δ 18OPDB值负偏移则可能是大气降水、深部热液等多种流体混合作用和成岩温度升高的影响造成的。车拐斜坡区碳酸盐胶结物的物质来源与有机酸脱羧产生的CO2、黏土矿物压实排水作用、长石碎屑溶蚀及黏土矿物相互转换释放大量的Ca 2+、Fe 3+和Mg 2+等离子有关,镜下观察发现研究区碳酸盐胶结物交代碎屑颗粒且伴随出现沥青质现象,以粉晶—粗晶形式赋存于排列紧密的碎屑颗粒之间,为成岩晚期产物,对储层物性起破坏作用。

关键词: 车拐斜坡区, 碳酸盐胶结物, 碳氧同位素, 物质来源, 储层物性

Abstract:

It is of great significance to clarify the formation mechanism of carbonate cementation and its influence on reservoir physical properties. By means of petrology and geochemistry, the occurrence characteristics and formation mechanism of carbonate cements in Cegai slope of Junggar Basin are analyzed. The results show that the distribution range of δ 13CPDB value is -29.6 ‰~6.7 ‰, that of δ 18OPDB value is -12.5 ‰~19.2 ‰, and it has a large span. All those indicate the material source of carbonate cementation and the complexity of water-rock interaction. δ 13CPDB value has a positive offset with the typical marine or lacustrine phase of carbonate, while δ 18OPDB value has the negative offset. The positive offset of δ 13CPDB value is mainly affected by the carbon isotope fractionation of mixed hydrothermal fluid and the dissolution of a small amount of sedimentary carbonate. The negative deviation of δ 18OPDB value may be caused by the mixing of various fluids—such as precipitation and deep hydrothermal—and the rise of diagenetic temperature. The material source of carbonate cements in Che-Guai slope is related to the CO2 produced by the decarboxylation of organic acids, compaction and drainage of clay minerals, the dissolution of feldspar debris and the release of a large amount of plasma like Ca 2+, Fe 3+ and Mg 2+ by conversion among clay minerals. Under the microscope, it is found that the carbonate cements are metasomatic to detrital particles and accompanied by asphaltene appearance, and appear in the form of crystal powder to macrocrystalline grain among the closely arranged clastic particles, as a product of late diagenetic stage, which destroy the physical properties of reservoirs.

Key words: Che-Guai slope area, carbonate cement, carbon and oxygen isotope, material source, reservoir physical properties

中图分类号: 

  • TE122