ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Economic Geology
Volume 13 - 2025 | doi: 10.3389/feart.2025.1635249
This article is part of the Research TopicAdvances in Accumulation Conditions of Unconventional Oil and Gas Resources in Complicated Structure AreasView all 7 articles
Characteristics and controlling factors of the Triassic Xu5 tight sandstone reservoirs, Western Sichuan Depression, China
Provisionally accepted
- 1Exploration and Development Research Institute, PetroChina Southwest Oil & Gasfield Company, Chengdu, China
- 2PetroChina Research Institute of Petroleum Exploration & Development, Beijing, China
- 3PetroChina Southwest Oil and Gasfield Company, Chengdu, China
- 4Northwest Sichuan Gas District, PetroChina Southwest Oil & Gasfield Company, Jiangyou, China
- 5Central Sichuan Oil & Gas District, PetroChima Southwest Oil & Gasfield Company, Suining, China
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The fifth member of the Xujiahe Formation in the West Sichuan depression of the Sichuan Basin has developed high-quality source rocks and large-scale delta distributary channel sediments, which have good potential for hydrocarbon accumulation, but the reservoir characteristics and genesis remain unclear. Based on the cast thin section, cathodoluminescence, X-ray diffraction, scanning electron microscope, and porosity and permeability data, the characteristics and controlling factors of physical properties of the tight sandstone reservoir in the fifth member of the Xujiahe Member were analyzed. The results show that the sandstone in the fifth member of the Xujiahe Formation sandstone is mainly being feldspar lithic sandstone and lithic sandstone, and with the reservoir space type is mainly lithic intragranular dissolution pores. The average porosity and permeability of the reservoir are 2.03% and 0.22 Md, respectively, which ismaking it an ultra-low porosity and extra-low permeability reservoir. The reservoir suffered fromhas undergone strong compaction and calcite and clay cementation. The provenance controlled the initial mineral composition of the reservoir, resulting in high rock fragment content and low quartz content in the northwest area., so This led to the physical properties of sandstones in the northwest area were being generally worse than those in the southwest source area.The sandstone in the delta front underwater distributary channel has low carbonate cements and matrix content, resulting in relatively goodso the reservoir physical properties are relatively good. Overall, The the lithic intragranular dissolution pores and microfractures are the key factors in improvingfactor to improve the physical properties of reservoirs.
Keywords: Tight sandstone, Digenesis, Reservoir quality, Xujiahe Formation, Western Sichuan Depression
Received: 26 May 2025; Accepted: 27 Aug 2025.
Copyright: © 2025 Wang, Wang, Li, Ma, Sun, Li, Zhang, Wang and Yang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Zhihong Wang, PetroChina Research Institute of Petroleum Exploration & Development, Beijing, China
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