Facies Architecture Model of the Shimentan Formation Pyroclastic Rocks in the Block‐T Units, Xihu Sag, East China Sea Basin, and its Exploration Significance

A gas field consisting of volcanic reservoir rocks was discovered in the block‐T units of the Xihu Sag, East China Sea Basin. The lithology of the volcanic rocks is dominated by tuff and reworked tuff. The lithofacies are dominated by base surge deposits of explosive facies. As the architecture mode...

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Bibliographic Details
Published in:Acta geologica Sinica (Beijing) 2019-08, Vol.93 (4), p.1076-1087
Main Authors: DAI, Xiaojuan, TANG, Huafeng, ZHANG, Tao, ZHAO, Pengjiu, XU, Chunming, KONG, Tan, ZHAO, Tianliang, WANG, Pujun
Format: Article
Language:English
Subjects:
Basins
Chips
Drilling
East China Sea Basin
eruptive stage
Exploration
facies architecture
Geochemistry
Geological time
Geomorphology
Grain size
Lava
Lithofacies
Lithology
Mineral exploration
Mineral resources
Oil and gas fields
Reservoirs
Rocks
Sag
Shimentan Formation
Tuff
Volcanic eruptions
Volcanic rocks
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Summary:A gas field consisting of volcanic reservoir rocks was discovered in the block‐T units of the Xihu Sag, East China Sea Basin. The lithology of the volcanic rocks is dominated by tuff and reworked tuff. The lithofacies are dominated by base surge deposits of explosive facies. As the architecture model of volcanic facies is still uncertain, it has restricted the exploration and development of mineral resources in this area. Using core and cuttings data, the lithology, lithofacies, geochemistry as well as grain size characteristics of volcanic rocks were analyzed. Based on these analyses, the volcanic rocks in the well section are divided into three eruptive stages. The transport direction of each volcanic eruption is analyzed using crystal fragment size analysis. The facies architecture of the block‐T units was established based on the reconstruction results of paleo‐geomorphology. The results show that the drilling reveals proximal facies (PF) and distal facies (DF) of the volcanic edifices. However, the crater‐near crater facies (CNCF) are not revealed. Compared with the reservoirs of the Songliao Basin, it is shown that the volcanic rocks in the Xihu Sag have good exploration potential; a favorable target area is the CNCF near the contemporaneous fault.
ISSN:1000-9515
1755-6724
DOI:10.1111/1755-6724.13807