Oil & Gas Geology ›› 2021, Vol. 42 ›› Issue (4): 949-962.doi: 10.11743/ogg20210415

• Petroleum Geology • Previous Articles     Next Articles

Occurrence, composition and origin of analcime in terrestrial lacustrine sedimentary rocks in China

Ye Jia1,2(), Shifa Zhu1,2,*(), Yi Yang1,2, Huan Tong1,2, Xiaomin Zhu1,2   

  1. 1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum(Beijing), Beijing 102249, China
    2. College of Geosciences, China University of Petroleum(Beijing), Beijing 102249, China
  • Received:2019-04-01 Online:2021-08-28 Published:2021-08-27
  • Contact: Shifa Zhu E-mail:493688330@qq.com;zhushifa_zsf@163.com

Abstract:

Natural analcime closely related to oil and gas reservoirs, is quite common in sedimentary rocks.We summarize the occurrence, composition, genesis of natural analcime and discuss its impact on reservoirs based on previous researches.The results show that analcime, a kind of silicate mineral containing crystalline water and of framework structure, is characterized by a silica-oxygen tetrahedron on map view to form a closed ring, and a cage structure in 3-D visualization space, the pore pathways in which are conducive to dissolution.There are five typical types of natural analcime in terrestrial lacustrine basins, among which the analcime with intergranular cements and fracture fillings is euhedral, and the exhalative analcime comes in two kinds of occurrence, namely, porhyritic texture and discontinuous coarse-grained laminae.The compositional differences of analcime concentrate on the content of Na and K ions: the K ion content tends to be higher, and the Si/Al ratio in analcime mainly ranges from 2.0 to 2.69, when it comes to alkaline volcanic rock as the host-rock.Among the four categories of natural analcime in terms of genesis, that in terrestrial lacustrine basins is mainly derived from diagenesis and hydrothermal exhalation.In all, sedimentary facies is key in the formation and dissolution of analcime; the analcime with intergranular cements is widely spread in the fan delta front developed from volcanic materials, while the analcime out of hydrothermal exhalation is common in the deep-semi-deep lacustrine subfacies; and dissolution of analcime by acidic fluid in the later stage is different in different sedimentary facies.

Key words: alteration of volcanic material, occurrence, exhalative rock, natural analcime, sedimentary rock, terrestrial lacustrine basin, China

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