石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (3): 707-719.doi: 10.11743/ogg20230314

• 油气地质 • 上一篇    下一篇

渤海湾盆地深层砂砾岩储层孔-缝成因机制及演化特征

张新涛1(), 曲希玉2(), 许鹏3, 王清斌3, 刘晓健3, 叶涛3   

  1. 1.中海石油（中国）有限公司 勘探开发部，北京 100010
    2.中国石油大学（华东） 地球科学与技术学院，山东 青岛 266580
    3.中海石油（中国）有限公司 天津分公司，天津 300459
  • 收稿日期:2022-12-05 修回日期:2023-02-17 出版日期:2023-06-01 发布日期:2023-06-05
  • 通讯作者: 曲希玉 E-mail:zhangxt4@cnooc.com.cn;quxiyu@upc.edu.cn
  • 第一作者简介:张新涛（1978—），男，博士、高级工程师，海上油气勘探。E-mail： zhangxt4@cnooc.com.cn。
  • 基金项目:
    国家自然科学基金项目(42272145);山东省自然科学基金项目(ZR2020MD027)

Genesis and evolution of pore-fractures in deep sandy conglomerate reservoirs in Bohai Bay Basin： Taking the Paleogene Kongdian Formation in Bozhong 19-6 structure as an example

Xintao ZHANG1(), Xiyu QU2(), Peng XU3, Qingbin WANG3, Xiaojian LIU3, Tao YE3   

  1. 1.Exploration Department，CNOOC，Beijing 100010，China
    2.School of Geosciences，China University of Petroleum （East China），Qingdao，Shangdong 266580，China
    3.Tianjin Branch，CNOOC，Tianjin 300459，China
  • Received:2022-12-05 Revised:2023-02-17 Online:2023-06-01 Published:2023-06-05
  • Contact: Xiyu QU E-mail:zhangxt4@cnooc.com.cn;quxiyu@upc.edu.cn

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摘要：

优质储层的识别和预测是深层-超深层碎屑岩储层油气勘探研究的重点。以渤海湾盆地渤中19-6构造古近系孔店组砂砾岩为研究对象，借助物理模拟实验等手段，研究了孔店组优质储集空间的成因及演化，建立了渤海湾盆地深层砂砾岩储层的孔-缝演化模式。取得的主要认识如下：①长石等颗粒的溶蚀孔为优质储集空间，钾长石的溶蚀随温度升高渐强甚至超过斜长石，钾长石在深层有更大的增孔潜力。②砾石级的颗粒、长英质的成分及低杂基含量更有利于压裂缝的产生，长石中压裂缝的发育程度要高于石英；垂向上，第一期压裂缝在2 500 m左右的深度开始形成，第二期压裂缝在3 000 m以深形成，而且其数量在4 000 m左右的深度达到峰值，第三期压裂缝在4 500 m以深开始形成，而且其数量随深度增大而逐渐增加。③孔隙度的垂向变化受到早期压实、晚期胶结以及中期溶蚀作用的控制。早期压实减孔17.38 %；晚期铁白云石胶结减孔7.76 %；有机酸溶蚀增孔5.45 %。④油气充注与第二期溶蚀增孔及第一期和第二期压裂缝的发育相对应，油气在3 000 m左右的深度处富集；4 000 m以深压裂缝大量发育，叠加钾长石等溶蚀，预测深层砂砾岩中发育优质储层。

关键词: 长石溶蚀, 压裂缝, 孔-缝演化, 砂砾岩, 深层, 渤中19-6构造, 渤海湾盆地

Abstract:

Mapping of quality reservoirs is critical to the successful exploration and discovery of deep- to ultra-deep clastic oil and gas reservoirs. This paper studies the genesis and evolution of storage space in high-quality and deep sandy conglomerate reservoirs in the Paleogene Kongdian Formation， Bozhong 19-6 structure， and establishes pore-fracture evolution models through physical simulation experiments and other means. The results show that： （1） pores formed by dissolution of feldspar particles are usually high-quality reservoir space. The dissolution of potassium feldspar intensifies or even exceeds that of plagioclase with rising temperature， indicating that potassium feldspar has greater potential for increasing porosity of deep layers. （2） Gravel-sized particles， felsic composition and low matrix content are more conducive to the generation of induced fractures， which are more highly developed in feldspar than in quartz. Vertically， induce fractures of the first stage appear at a burial depth of about 2 500 m， that of the second stage appear at a depth larger than 3 000 m with their number peaking at about 4000 m deep， and that of the third stage appear at a depth greater than 4 500 m with their amount increasing with the increasing depth. （3） Vertically， porosity is damaged by early compaction and late cementation but improved by dissolution occurring in between： the early compaction reduced the porosity by 17.38 % and the late ankerite cementation reduced the porosity by 7.76 %， while organic acid dissolution between the two processes increased the porosity by 5.45 %. （4） Hydrocarbon charging is well timed relative to the second-stage dissolution with porosity enhancement， and the first- and second-stage induced fracture development， thus， hydrocarbons enrich in reservoirs at about 3 000 m deep. In addition， high-quality reservoirs may occur in the deep sandy conglomerate at 4 000 m deep， where the mass development of induced fractures， together with the dissolution such as potassium feldspar， greatly enhance reservoir quality.

Key words: feldspar dissolution, induced fracture, evolution of pore-fracture, sandy conglomerate, deep strata, Bozhong 19-6 structure, Bohai Bay Basin

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