石油与天然气地质 ›› 2019, Vol. 40 ›› Issue (4): 886-899.doi: 10.11743/ogg20190417

• 油气地质 • 上一篇    下一篇

岩相约束下的深层致密砂岩气藏储层演化特征

林建力1, 张宪国1,2, 林承焰1,2, 段冬平3, 黄鑫3, 孙小龙1, 董春梅1,2   

  1. 1. 中国石油大学(华东) 地球科学与技术学院, 山东 青岛 266580;
    2. 山东省油藏地质重点实验室, 山东 青岛 266580;
    3. 中海石油(中国)有限公司 上海分公司 勘探开发研究院, 上海 200335
  • 收稿日期:2017-12-13 修回日期:2019-01-14 出版日期:2019-08-28 发布日期:2019-06-01
  • 通讯作者: 张宪国(1982-),博士、副教授,储层地质学。E-mail:dzzs1982@163.com。 E-mail:dzzs1982@163.com
  • 作者简介:林建力(1992-),博士研究生,储层地质学。E-mail:real_lin@163.com。
  • 基金资助:
    国家科技重大专项(2016ZX05027-004);国家自然科学基金项目(41672129&41602135)。

Diagenetic evolution characteristics constrained by lithofacies in deep tight sand gas reservoir

Lin Jianli1, Zhang Xianguo1,2, Lin Chengyan1,2, Duan Dongping3, Huang Xin3, Sun Xiaolong1, Dong Chunmei1,2   

  1. 1. School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China;
    2. Key Laboratory of Reservoir Geology, Qingdao, Shandong 266580, China;
    3. Research Institute of Exploration and Development of Shanghai Branch Company Ltd., CNOOC, Shanghai 200335, China
  • Received:2017-12-13 Revised:2019-01-14 Online:2019-08-28 Published:2019-06-01

摘要: 东海盆地深层致密气藏沉积和成岩演化复杂,不同岩相储层的成岩演化是揭示沉积-成岩耦合及认识致密储层甜点成因的关键,也是甜点预测的基础。本研究将岩心观察、铸体薄片、扫描电镜、粒度分析和X-衍射等资料相结合,选取东海西湖凹陷中央反转构造带深层花港组典型致密气藏,研究不同岩相储层的成岩演化。通过开展岩石学特征研究,划分主要岩相类型,结合埋藏史分析成岩演化序列,分析不同岩相砂岩成岩差异及成岩演化过程,建立不同岩相的成岩演化模式,揭示沉积对成岩的控制作用。结果表明,研究区花港组储层以水下分流河道沉积为主体,主要发育块状层理中-粗砂岩、砾质砂岩、平行层理中-细砂岩和泥砾质砂岩四种岩相类型。块状层理中-粗砂岩和砾质砂岩刚性石英含量较高,粘土含量较低,胶结物类型以薄层绿泥石和硅质胶结为主;前者经历的成岩作用较为完整,埋藏后期仍然发育有一定的原生孔隙和次生溶孔,容易形成较好储层;但后者常常因为分选性较差,最终易形成压实紧密,硅质胶结强烈的致密储层。平行层理中-细砂岩刚性石英含量较低,粘土含量较高,胶结物类型以厚层绿泥石、伊/蒙混层和伊利石相伴生为主;由于沉积分异作用,碎屑颗粒常呈层状定向排列,埋藏后期细粒层部分压实致密,粗粒层部分保留有块状层理砂岩性质,发育局部孔隙带,形成次一级储层;泥砾质砂岩塑性泥岩撕裂屑含量较高,同时混杂有大量泥质杂基,在埋藏早期就已经压实致密,各类孔隙均不发育,基本为非储层。

关键词: 甜点预测, 岩相, 成岩作用, 成岩演化, 致密储层, 致密砂岩气藏, 花港组, 西湖凹陷, 东海盆地

Abstract: The sedimentary and diagenetic evolution of the deep tight gas reservoir in the East China Sea Basin is complex.The diagenetic evolution of different lithofacies reservoirs is key to revealing the sedimentary-diagenetic coupling, to understand the genetic mechanism of "sweet spot" in tight reservoirs, and also to lay a sound foundation for "sweet spot" prediction.A case study of the typical tight gas reservoir in the Huagang Formation located in the deep central structural inversion belt of the Xihu Depression, East China Sea Basin, reveals the diagenetic evolution of various lithofacies reservoirs through core observation, SEM, casting thin section, granularity and X-ray diffraction analyses.The control of deposition on diagenesis is revealed by our diagenetic evolution models for different lithofacies reservoirs, which are based on petrological characterization, classification of main lithofacies types, and analysis of diagenetic evolution sequence and burial-thermal evolution history.The results show that the sediments in underwater distributary channels constituting the main body of the Huagang Formation reservoirs in the braided-river delta front, have mainly developed four lithofacies types, namely massive medium-to-coarse grained sandstones, gravel sandstones, medium-to-fine grained sandstones with parallel bedding and muddy gravel sandstones.The massive medium-to-fine grained and gravel sandstones is high in rigid quartz content, but low in clay content, with dominant thin chlorite and siliceous cements.However, the best reservoir quality is observed in massive medium-to-coarse grained sandstones due to their relatively complete diagenetic process and growth of primary and secondary solution pores at the later buried stage.In contrast, the gravel sandstones are prone to generate tight reservoirs characterized by greater compaction and intense siliceous cementation due to their poor sorting.In addition, the medium-to-fine grained sandstones with parallel beddings, mainly associated with thick chlorite, I/S mixed layer and illite, feature low content of rigid quartz but high clay content.Clastic particles tend to arrange directio-nally in lamina due to sedimentary differentiation:the fine-grained laminae favor stronger compaction at later stage of diagenesis that helps the preservation of local primary porosity in the coarse-grained part, generating reservoir pockets.Muddy gravel sandstones contain lots of pelinite clasts as well as argillaceous matrix, and they have undergone stronger compaction at the eogenetic stage, resulting in destruction of porosity and reservoir quality.

Key words: sweet spot prediction, lithofacies, diagenesis, diagenetic evolution, tight reservoir, tight sand gas reservoir, Huagang Formation, Xihu sag, East China Sea Basin

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