新疆石油地质

新疆石油地质 ›› 2019, Vol. 40 ›› Issue (zk(English) ): 174-180.

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Laumontite Cementation Characteristics and Their Influences on Reservoir Physical Properties in Chang 6 Member of Qilicun Oilfield, Ordos Basin

DU Guichao1, SHI Lihua2, MA Xiaofeng3, CAO Qing1, DING Chao1, SHEN Zhenzhen4   

  1. 1.School of Earth Sciences & Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China;
    2.Research Institute, Shanxi Yanchang Petroleum (Group) Co. Ltd., Xi’an, Shaanxi 710075, China;
    3.Key Laboratory of Petroleum Resources Research, Lanzhou, Gansu 730000, China;
    4.Qilicun Oil Production Plant, Yanchang Oilfield Company, Yan'an, Shaanxi 717111, China
  • 收稿日期:2018-08-26 修回日期:2018-12-05 出版日期:2020-01-01 发布日期:2021-05-18

Laumontite Cementation Characteristics and Their Influences on Reservoir Physical Properties in Chang 6 Member of Qilicun Oilfield, Ordos Basin

DU Guichao1, SHI Lihua2, MA Xiaofeng3, CAO Qing1, DING Chao1, SHEN Zhenzhen4   

  1. 1.School of Earth Sciences & Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China;
    2.Research Institute, Shanxi Yanchang Petroleum (Group) Co. Ltd., Xi’an, Shaanxi 710075, China;
    3.Key Laboratory of Petroleum Resources Research, Lanzhou, Gansu 730000, China;
    4.Qilicun Oil Production Plant, Yanchang Oilfield Company, Yan'an, Shaanxi 717111, China
  • Received:2018-08-26 Revised:2018-12-05 Online:2020-01-01 Published:2021-05-18
  • About author:DU Guichao, E-mail: duguichao@sina.com

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摘要： To deepen the understandings about geological features of oil and gas in Qilicun oilfield, regarding laumontite development, cementation mechanism and their influences on reservoir physical properties in Chang 6 member of Yanchang formation and based on the porosity and permeability analysis, thin section identification and SEM analysis, the paper performs a systematic study on the diagenesis of sandstones in Chang 6 member. The results show that 3 stages of laumontite are developed in the Chang 6 member, namely syndiagenetic, early diagenetic stage A and late diagenetic stage A. In the syndiagenetic stage, laumontite cementation was mainly influenced by sedimentary environment and provenance, and the hydrations of metamorphic debris and vitric minerals in igneous rock debris in the sandstone of Chang 6 member provided enough materials for the generation of the early laumontite. In the early diagenetic stage A, albitization of anorthose provided the important material basis for the cementation of laumontite. In the late diagenetic stage A, the cementation was related to the oversaturated precipitation of laumontite, and the Ca2+ and SiO2 came from the dissolutions of early laumontite, feldspar and debris. The laumontite cementation was closely related to the reservoir physical properties of Chang 6 member. The early laumontite cementation prevented debris from further compaction and also provided favorable conditions for the formation of secondary pores during late dissolutions. The dissolution of the laumontite expanded the pore spaces of the reservoir and improved the pore throat structure and connectivity during the late diagenetic stage A.

关键词: Ordos basin, Qilicun oilfield, Yanchang formation, diagenesis, laumontite, cementation, reservoir physical property

Abstract: To deepen the understandings about geological features of oil and gas in Qilicun oilfield, regarding laumontite development, cementation mechanism and their influences on reservoir physical properties in Chang 6 member of Yanchang formation and based on the porosity and permeability analysis, thin section identification and SEM analysis, the paper performs a systematic study on the diagenesis of sandstones in Chang 6 member. The results show that 3 stages of laumontite are developed in the Chang 6 member, namely syndiagenetic, early diagenetic stage A and late diagenetic stage A. In the syndiagenetic stage, laumontite cementation was mainly influenced by sedimentary environment and provenance, and the hydrations of metamorphic debris and vitric minerals in igneous rock debris in the sandstone of Chang 6 member provided enough materials for the generation of the early laumontite. In the early diagenetic stage A, albitization of anorthose provided the important material basis for the cementation of laumontite. In the late diagenetic stage A, the cementation was related to the oversaturated precipitation of laumontite, and the Ca2+ and SiO2 came from the dissolutions of early laumontite, feldspar and debris. The laumontite cementation was closely related to the reservoir physical properties of Chang 6 member. The early laumontite cementation prevented debris from further compaction and also provided favorable conditions for the formation of secondary pores during late dissolutions. The dissolution of the laumontite expanded the pore spaces of the reservoir and improved the pore throat structure and connectivity during the late diagenetic stage A.

Key words: Ordos basin, Qilicun oilfield, Yanchang formation, diagenesis, laumontite, cementation, reservoir physical property