CHEN S R，WANG X，WANG L J，et al. The Triassic Shipao Formation in Youjiang Basin: A preliminary study on the potential of new shale gas formations in South China [J]. Journal of Henan Polytechnic University( Natural Science), doi:10.16186/j.cnki.1673- 9787. 2025020011. 

Received：2025-02-11

Revised：2025-04-24

Online：2025-05-12

The Triassic Shipao Formation in Youjiang Basin: A preliminary study on the potential of new shale gas formations in South China (Online)

CHEN Shangren¹, WANG Xiang¹,WANG Laijun¹,HUANG Wenfang¹,CEN Wenpan^1,2,QIN Yinglun^3,4,LUO Yujie¹，CHEN Jiyu¹,ZHANG Jingxian¹,LU Wenshi³

(1. Guangxi Institute of Geological Survey, Nanning 530031, Guangxi, China; 2. Key Laboratory of Tectonics and Petroleum Resources of the Ministry of Education, China University of Geosciences( Wuhan) , Wuhan 430074, Hubei, China;3. Guangxi Energy Group Co. , Ltd. , Nanning 530000, Guangxi,China;4. School of Earth Sciences, China University of Petroleum( Beijing) , Beijing 102299, China)

Abstract: Objectives The Triassic Shihu Formation in Youjiang Basin, as a new layer of Marine shale gas strategic breakthrough in the periphery of Sichuan Basin, shows significant exploration potential. However, shale gas exploration and research in this area are relatively scarce at present. In order to further explore the geological conditions of shale gas enrichment of Shihu Formation and accurately analyze its shale gas exploration potential. Methods Based on the field investigation of Shihu Formation in Youjiang Basin, this study comprehensively applied shallow core drilling, organic geochemical analysis, whole rock X-ray diffraction test, scanning electron microscopy (SEM) observation, methane isothermal adsorption experiment and other technical means. The shale gas source rock conditions, reservoir conditions and preservation conditions of Lower Triassic Shipao Formation are systematically analyzed, and the shale gas enrichment potential of Lower Triassic Shipao Formation is evaluated by comparing with typical blocks at home and abroad. Results The results show that: (1) The Shisha formation mainly develops in the basin or slope facies zone, in which the basin facies is more conducive to the enrichment of organic matter, and the thickness of the rich organic shale in the sedimentary center is usually between 50 and 120 meters. (2) The total organic carbon (TOC) content ranges from 0.21% to 12.30% (average 1.52%), the distribution of high TOC value is mainly controlled by sedimentary rock facies, and the organic matter type is mainly Ⅰ-Ⅱ, which is in the over-mature stage and has good hydrocarbon supply capacity; (3) The shale reservoir has a high content of brittle minerals and moderate content of clay minerals, which has a certain potential for fracturing reform. The reservoir pores are dominated by inorganic pores represented by mineral dissolution pores, providing more space for the occurrence of free gas; (4) Multi-stage tectonic movements have a great impact on the preservation of shale gas, but in the present Triassic remnant thickness is large, buried depths in the moderate range of 500 to 3500 meters, there are still good preservation Conclusions Compared with the geological conditions of shale gas in typical blocks at home and abroad, the sedimental-structural background of the Shihuo Formation shale in Youjiang Basin is more complex, but its organic-rich shale has larger thickness, high content of brittle minerals, and good adsorption performance. Comprehensive research and evaluation suggest that it still has good conditions for shale gas enrichment. The Bama - Yandong - Natao area is clearly proposed as a favorable area for shale gas exploration.

Key words：new zone; new stratification; shale gas; Youjiang Basin; enrichment conditions

CLC: TE121.1