石油与天然气地质 ›› 2015, Vol. 36 ›› Issue (4): 545-554.doi: 10.11743/ogg20150403

• 油气地质 • 上一篇    下一篇

川西坳陷中段沙溪庙组砂岩中水-岩-烃作用特征

吕正祥1, 杨相1, 卿元华1,2, 叶素娟3   

  1. 1. 成都理工大学 能源学院, 四川 成都 610059;
    2. 中国石油 塔里木油田分公司, 新疆 库尔勒 841000;
    3. 中国石化 西南油气田分公司, 四川 成都 610081
  • 收稿日期:2015-04-13 修回日期:2015-07-01 出版日期:2015-08-08 发布日期:2015-08-28
  • 作者简介:吕正祥(1965—),男,博士、教授级高级工程师,油气地质。E-mail:417330439@qq.com。
  • 基金资助:

    国家自然科学基金项目(41172119)。

Water-rock-hydrocarbon interactions in the Middle Jurassic Shaximiao Formation sandstones, Western Sichuan

Lv Zhengxiang1, Yang Xiang1, Qing Yuanhua1,2, YE Sujuan3   

  1. 1. College of Energy Resources, Chengdu University of Technology, Chengdu, Sichuan 610059, China;
    2. Tarim Oilfield Company, PetroChina, Korla, Xinjiang 841000, China;
    3. Southwest Oilfield Company, SINOPEC, Chengdu, Sichuan 610081, China
  • Received:2015-04-13 Revised:2015-07-01 Online:2015-08-08 Published:2015-08-28

摘要:

通过显微岩石矿物学分析、扫描电镜与能谱分析、阴极发光分析等确定了伴随川西坳陷中侏罗统沙溪庙组砂岩孔隙流体演化形成的自生矿物类型与产出关系,利用包裹体温度分析、同位素地质温度分析等确定了主要自生矿物的形成时期,主要利用电子探针微区成分分析技术测定了不同阶段形成的自生矿物的化学组成,并运用同位素分析、地层水分析、粘土矿物X-射线衍射分析等技术进一步获得了孔隙流体的演化特征。沙溪庙组砂岩孔隙流体早期富镁、富铁、偏碱性,随着埋深的增加和烃类的进入等逐渐向偏酸性演化,在转化过程中形成了绿泥石、石英、方解石、高岭石等矿物。自生绿泥石消耗了镁离子和铁离子,钠长石的溶蚀提供了钠离子,烃类注入提供了酸性流体,导致孔隙流体最终演化为现今富钠、富钙、偏酸性的CaCl2型地层水特征。溶蚀作用改善了储层的储集性,自生绿泥石孔隙衬垫保护了原生孔隙,有利于形成有利储层。

关键词: 水-岩-烃作用, 砂岩储层, 沙溪庙组, 中侏罗统, 川西坳陷

Abstract:

Water-rock-hydrocarbon interactions in the Middle Jurassic Shaximiao Formation sandstones, Western Sichuan, were studied to determine the relationship between authigenic mineral types and hydrocarbon generation through analyses of petrographic data, and scanning electron microscopy and cathode luminescence results.Formation timing of major authigenic minerals was also determined with analyses of inclusion temperature and isotope geo-temperature.Electron microprobe was employed to measure the chemical compositions of the minerals of different forming ages.Isotope analyses and formation water analyses were combined with X-ray diffraction to describe the evolving features of pore fluids of the formation.The result shows that the pore fluid in the Shaximiao Formation was originally characterized by high contents of Mg2+ and Fe2+, and high pH value.As burial depth increased and hydrocarbon entered, the fluid gradually turned acid and formed minerals such as chlorite, quartz, calcite, kaolinite, and etc, during the process.With authigenic chlorite consuming Mg2+, and Fe2+, feldspar providing Na+ and the charging of hydrocarbon providing acidic fluids, the pore fluids finally turned into this CaCl2 type low-pH formation water with high content of Na+ and Ca2+.It should be noted that there are two factors that were favorable for the formation of good reservoirs:dissolution improved storage capacity of reservoirs and authgenic chlorite formed pore rim and helped preserving primary pores during the diagenetic process.

Key words: water-rock-hydrocarbon interaction, sandstone reservoir, the Shaximiao Formation, the Middle Jurassic, western Sichuan depression

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