Western Sichuan is located in a complex foreland thrust system, where intense multi-stage tectonic deformation makes hydrocarbon preservation a critical control on accumulation and exploration success. Focusing on the Middle Permian strata, this study aims to systematically evaluate hydrocarbon preservation conditions and clarify their spatial variability. Based on integrated seismic interpretation, formation water geochemistry, pressure data and regional geological and exploration information, a multi-indicator evaluation framework was established, incorporating tectonic deformation intensity (fault distance and fault development), exposed strata, caprock integrity and formation water characteristics. The results reveal a clear zonation of preservation conditions across western Sichuan. Near the Longmenshan fault front, dense faulting, severe caprock destruction and low-salinity NaHCO3–Na2SO4-type formation water indicate an open system with poor preservation. In the basin–mountain transition zone, fault activity weakens and partial caprock preservation remains, accompanied by moderate-salinity mixed NaHCO3–CaCl2 water, reflecting intermediate preservation. Towards the basin interior, structures become stable and closed, regional gypsum–mudstone caprocks are well developed, and high-salinity CaCl2-type brines dominate, indicating long-term sealed systems and favourable preservation. These conditions are confirmed by multiple high-yield gas discoveries, including the Pingluoba-1 well with a tested gas flow of 66.76 × 104 m3/d. The proposed multi-indicator evaluation method and preservation zonation provide a robust geological basis for optimising exploration strategies in complex foreland basins such as western Sichuan.
SunZ. Superimposed hydrocarbon accumulation through multi-source and multi-stage evolution in the Cambrian Xixiangchi Group of eastern Sichuan Basin: a case study of the Pingqiao gas-bearing anticline. Energy Geosci2023; 4: 131–142.
2.
LiHQinQLiC, et al.Quantitative characterization of complex multi-scale fractures in low-permeable sandstone reservoir: Insights from geological and mathematical approach. Geomech Geophys Geo-Energ Geo-Resour2026. 10.1007/s40948-026-01117-7
3.
LiJHuangTLiH, et al.Geological characteristics and three-dimensional development potential of deep shale gas in the Luzhou area, southern Sichuan Basin, China. J Geo-Energy Environ2025; 1: 32–44.
4.
LiHTangHQinQ, et al.Effectiveness evaluation of natural fractures in Xujiahe Formation of Yuanba area, Sichuan Basin, China. Arabian J Geosci2019; 12: 194.
5.
HuangYWangAXiaoK, et al.Types and genesis of sweet spots in the tight sandstone gas reservoirs: insights from the Xujiahe Formation, northern Sichuan Basin, China. Energy Geosci2022; 3: 270–281.
6.
WangHShiZZhaoQ, et al.Stratigraphic framework of the Wufeng–Longmaxi shale in and around the Sichuan Basin, China: implications for targeting shale gas. Energy Geosci2020; 1: 124–133.
7.
LiH. Integrated application of gravity, aeromagnetic, and electromagnetic methods in exploring the Ganzi geothermal field, Sichuan Province, China. Energy Geosci2023; 4: 100207.
8.
ChenQDongYTanX, et al.Application of extended tilt angle and its 3D Euler deconvolution to gravity data from the Longmenshan thrust belt and adjacent areas. J Appl Geophys2022; 2: 104769.
9.
ChenYZhangGLuR, et al.Kinematics and geometry of the Yanjing–Wulong Fault in the southern section of Longmenshan tectonic belt: constraints from magnetic fabrics. Geotecton Metallogen2019; 2: 199–212.
10.
DengBZhaoGWanY, et al.A review of tectonic sandbox modeling of fold-and-thrust belt. Geotecton Metallogen2016; 40: 446–464.
11.
WuLHouZLiY, et al.Carbon circular utilization and sequestration in depleted hydrocarbon reservoirs: towards a carbon-neutral China. Energy Geosci2025; 6: 100343.
12.
WeiGYangWLiuM, et al.Distribution rules, main controlling factors and exploration directions of giant gas fields in the Sichuan Basin. Nat Gas Indus2020; 7: 1–12.
13.
FanCCaoHLiJ, et al.Comprehensive evaluation of the hydrocarbon preservation conditions in the complex tectonic area of the southwestern Sichuan Basin, China. Geofluids2023; 2023: 6415397.
14.
LiBMeiWLiQ, et al.Influence of tectonic evolution of the foreland basin in northwestern Sichuan Basin on Paleozoic marine hydrocarbon accumulation. Nat Gas Geosci2020; 7: 993–1003.
15.
LiMLiWCaiF. Integrative study of preservation conditions of oil and gas pools. Acta Pet Sin1997; 18: 41–48.
16.
WangJZhengXXieX, et al.Fault sealing evaluation and its effect on hydrocarbon accumulation in buried-hill fault-block oilfields, Bohai Bay Basin, China. Appl Earth Sci2025; 0. doi:10.1177/25726838251406961
17.
HeDLiDZhangG, et al.Formation and evolution of multi-cycle superimposed basins in the Sichuan Basin. Geol Sci2011; 46: 589–606.
18.
MaYLouZGuoT, et al.An exploration on a technological system of petroleum-preservation evaluation for marine strata in southern China. Acta Geol Sin (English Edition)2006; 80: 406–417.
19.
LouZMaYGuoT, et al.Evaluation of oil and gas preservation conditions in marine formation in South China. Nat Gas Indus2006; 26: 8–11.
20.
LiangX. The comprehensive evaluation of hydrocarbon preservation units in marine strata of southern China reconstructed basins. Chengdu: Southwest Petroleum University, 2006.
21.
XiaoC. Study on the preservation conditions of marine oil and gas in the Zhong-Yangtze region. Chengdu: Chengdu University of Technology, 2010.
22.
LuoXLiSHeX, et al.Hydrocarbon preservation conditions in Longmen Mountain, west Sichuan Basin. Pet Geol Exp2010; 32: 10–14.
23.
WangXWoYZhouY, et al.Research progress on the influence of tectonic activity on oil-and-gas preservation: a case study of the Upper Yangtze region. Pet Geol Exp2011; 33: 34–42.
24.
LiF. Study on groundwater characteristics and hydrocarbon-preservation conditions in the Micang–Dabashan fore-belt. Zhejiang: Zhejiang University, 2014.
25.
DengD. Chemical characteristics of Triassic-Jurassic formation water and its relationship to hydrocarbon preservation in the west of Sichuan Basin. Mar Orig Pet Geol2015; 20: 62–70.
26.
HeZLiSWoY, et al.Major factors controlling hydrocarbon preservation conditions in marine basins of China and evaluation ideas. Acta Pet Sin2017; 33: 1221–1232.
27.
ZhangPLiangJChenJ, et al.Analysis of hydrocarbon-preservation conditions in deep marine strata of superimposed basins in China. Mar Geol Front2019; 35: 1–11.
28.
LiuRHuZYangL,et al.Shale gas preservation evaluation based on stratigraphy-fracture index: a case study from the Youjiang Basin. J Pet Sci Eng2024; 235: 112345.
29.
YangZTaoGBaoY, et al.Differential development and maintenance mechanism of reservoir space for marine shale gas in South China's deep strata. Pet Geol Exp2022; 44: 845–853.
30.
National Energy Technology Laboratory (NETL). NETL helps develop microscopic cementing agents to seal underground fractures. U.S. Department of Energy, 2025, March 4. https://netl.doe.gov/node/12406
31.
GuoXHuDYuL, et al.Study on the micro mechanism of shale self-sealing and shale gas preservation. Pet Geol Exp2023; 45: 821–831.
32.
FengYXiaoXWangE, et al.Gas storage in shale pore system: a review of the mechanism, control and assessment. Pet Sci2023; 20: 2605–2636.
33.
ShaoDEllisGSLiJ,et al.Effects of pressure on gas generation and pore evolution in thermally matured calcareous mudrock: insights from gold-tube pyrolysis of the Eagle Ford Shale using miniature core plugs. Mar Pet Geol2022; 145: 105887.
34.
YuanYHaoYZhangR. Dynamic evaluation on sealing capacity of caprocks of the Meso-Neoproterozoic reservoirs in Ordos Basin, China. Energy Geosci2024; 5: 100226.
35.
RenGGuoWYuanL. Quantitative assessment of shale gas preservation in the Longmaxi Formation: insights from Shale fluid properties. J Geo-Energy Environ2025; 1: 8–22.
36.
BianQZhangJHuangC. The middle and lower Cambrian salt tectonics in the central Tarim basin, China: a case study based on strike-slip fault characterization. Energy Geosci2024; 5: 100254.
37.
ZhangPXuDFuX, et al.Evaluation of hydraulic conductivity based on fault confinement studies. J Min Strata Control Eng2022; 4: 023033.
38.
HeSTanWCLiH, et al.Mineralogical and lithofacies controls on gas storage mechanisms in organic-rich marine shales. Energy Fuels2025; 39: 3846–3858.
39.
LiJZhangQJiangW, et al.Lithological controls on pore structure and their implications for deep shale gas reservoir quality in the Longmaxi Formation, Luzhou area, Southern Sichuan Basin, China. Energy Fuels2025; 39: 1541–1558.
40.
DongJWeiGChenZ, et al.Longmen Shan fold-thrust belt and its relation to the western Sichuan Basin in central China: new insights from hydrocarbon exploration. AAPG Bull2006; 90: 1425–1447.
41.
ShaoXLiuZLiuZ, et al.Seismic prediction and geological development mode of fault-fracture bodies in the 2nd Member of Xujiahe Formation in Xinchang area of western Sichuan Depression. Pet Geol Recov Efficiency2022; 4: 1–11.
42.
LiuZLiuZGuoY, et al.Concept and geological model of fault-fracture reservoir and their application in seismic fracture prediction: a case study on the Xu₂ Member tight sandstone gas pool in Xinchang area, Western Sichuan depression, Sichuan Basin. Oil Gas Geol2021; 42: 973–980.
43.
LiHDuanHTQinQR, et al.Characteristics and distribution of tectonic fracture networks in low permeability conglomerate reservoirs. Sci Rep2025; 15: 5914.
44.
FuGSuXSheY, et al.Evidence for normal and deep-buried features of the Longquan Shan fault zone at the eastern margin of the Tibetan Plateau. J Asian Earth Sci2019; 179: 56–64.
45.
JiangDZhangSLiW,et al.Foreland deformation pattern of the southern Longmen Shan in late quaternary. Acta Geophys Sin2018; 5: 1949–1969.
46.
LiuSLuoZZhaoX, et al.Coupling relationships and dynamic model of Basin–Orogen systems in western China: a case study of the Longmen Shan orogenic belt–western Sichuan foreland basin system. Acta Geol Sin2003; 77: 177–186.
47.
ZhengCZhangBLiR, et al.Facies-controlled prediction of dolomite reservoirs in the middle Permian Qixia Formation in Shuangyushi, northwestern Sichuan Basin. Energy Geosci2024; 5: 100230.
48.
ZhaoHZhangZZhaoR, et al.Three-pressure prediction method of jointing well-seismic data in the JT1 well area of the Sichuan Basin, China. Sci Rep2024; 14: 16044.
49.
ZhangBLiuLZhengA, et al.Enhanced understanding of carbonate-rich shale heterogeneity through multifractal characterization based on N₂ adsorption data: a case study of the Permian Wujiaping Formation in the Sichuan Basin. Energy Geosci2025; 6: 100426.
50.
LiHTangHMQinQR, et al.Characteristics, formation periods and genetic mechanisms of tectonic fractures in the tight gas sandstones reservoir: a case study of the Xujiahe formation in YB area, Sichuan Basin, China. J Pet Sci Eng2019; 178: 723–735.
51.
LuHMaZLiH, et al.Pore connectivity evaluation and seepage characteristic of ultra-deep carbonate reservoirs of Permian Qixia Formation in NW Sichuan Basin. Sci Rep2025; 15: 26580.
52.
LiHQinQZhangB, et al.Tectonic fracture formation and distribution in ultradeep marine carbonate gas reservoirs: a case study of the Maokou formation in the Jiulongshan gas field, Sichuan Basin, China. Energy Fuels2020; 34: 14132–14146.
53.
YadavAYadavKSircarA, et al.Feedforward neural network for joint inversion of geophysical data to identify geothermal sweet spots in Gandhar, Gujarat, India. Energy Geosci2021; 2: 189–200.
54.
RadwanAE. Integrated perspectives on sedimentary systems, tectonics, and hydrocarbon potential. Appl Earth Sci2026; 0. doi:10.1177/25726838261418485
55.
FanCXieHLiH, et al.Complicated fault characterization and its influence on shale gas preservation in the southern margin of the Sichuan Basin, China. Lithosphere2022; Special 12: 8035106.
56.
WuCYangZQinY, et al.Characteristics of hydrogen and oxygen isotopes in produced water and productivity response of coalbed methane wells in western Guizhou. Energy Fuels2018; 32: 11203–11211.
57.
TogozoFTBoboyeOATchouatchaMS, et al.Integrated sedimentological, petrographic and mineralogical analysis of provenance and diagenesis in the Carnot-Berberati Basin, Central African Republic (CAR). Appl Earth Sci2025; 0. doi:10.1177/25726838251387439
58.
HeDSuppeJJiaC, et al.Fault-related folding theory and its application: new advances. Geosci Front2005; 12: 353–364.
59.
ZengSQiuNLiH, et al.Generation and distribution of overpressure in ultra-deep carbonate reservoirs controlled by intra-cratonic strike-slip faults: the Ordovician of Shuntuoguole area in the Tarim Basin. Mar Pet Geol2023; 158: 106515.
60.
ChaiYYinS. 3D Displacement discontinuity analysis of in-situ stress perturbation near a weak fault. Adv Geo-Energy Res2021; 5: 286–296.
61.
LiJQinQLiH, et al.Numerical simulation of the stress field and fault sealing of complex fault combinations in Changning area, Southern Sichuan Basin, China. Energy Sci Eng2022; 10: 278–291.
62.
ShiSShanCZhaoZ, et al.Organic geochemical characteristics and thermal evolution characteristics of Paleogene to Neogene Source Rocks in Mangai Area, Qaidam Basin. J Geo-Energy Environ2026; 2: 56–72.
63.
OuyangSLüXQuanH, et al.Evolution process and factors influencing the tight carbonate caprock: ordovician Yingshan Formation from the northern slope of the Tazhong uplift, Tarim Basin, China. Mar Pet Geol2023; 147: 105998.
64.
CaiM. Key theories and technologies for surrounding rock stability and ground control in deep mining. J Min Strata Control Eng2020; 2: 033037.
65.
LiSJiaAHuQ, et al.Particle size effect on water vapor sorption measurement of organic shale: one example from Dongyuemiao member of lower Jurassic Ziliujing Formation in Jiannan area of China. Adv Geo-Energy Res2020; 4: 207–218.
66.
ZengSQiuNLiH, et al.Generation and distribution of overpressure in ultra-deep carbonate reservoirs controlled by intra-cratonic strike-slip faults: the Ordovician of Shuntuoguole area in the Tarim Basin. Mar Pet Geol2023; 158: 106510.
67.
MaWZhouXTanS, et al.Study on failure characteristics of coal seam floor above confined water: a case study of Shanxi Yitang Coal Mine. J Min Strata Control Eng2020; 2: 033011.
68.
DaiHLiuSSunW, et al.Study on surface asphalt characteristics of the lower stratigraphic assemblage in the Longmen Shan–Micang Shan area, western China. J Chengdu Univ Technol2009; 36: 687–696.
69.
LiuGWangSPanW, et al.Study on the ancient oil reservoirs at Tianjing Shan, Guangyuan, Sichuan. Mar Orig Pet Geol2003; 8: 103–107.
70.
LiAHeJLiJ, et al.Experimental study on the influence of water–rock interaction on the mechanical characteristics and creep behavior of shale. J Geo-Energy Environ2025; 1: 61–69.
71.
AbubakarYTaylorKGCokerV, et al.Fundamental controls on organic matter preservation in organic- and sulfur-rich hydrocarbon source rocks. Mar Pet Geol2022; 141: 105684.
72.
ZiliFFuHFanX, et al.Prediction method of vertical sealing evolution form and distribution position of oil source faults. Sci Rep2025; 15: 33239.
73.
LiHTangHQinQ, et al.Reservoir characteristics and hydrocarbon accumulation of carboniferous volcanic weathered crust of Zhongguai high area in the western Junggar Basin, China. J Central South Univ2018; 25: 2785–2801.
74.
FanCNieSLiH, et al.Geological characteristics and major factors controlling the high yield of tight oil in the Da’anzhai Member of the western Gongshanmiao in the central Sichuan Basin, China. Geomech Geophy Geo-Energy Geo-Resour2024; 10: 67.
75.
ZhangDRenFWangJ, et al.Rock mass caving and movement mechanisms of block caving mining. J Min Strata Control Eng2021; 3: 033521.
76.
GuoYLuoFLiM, et al.Development and evolution of tension-shear failure network of surrounding rock in square roadway. J Min Strata Control Eng2022; 4: 023025.
77.
ZhangLLiCLuoX, et al.Vertically transferred overpressures along faults in Mesozoic reservoirs in the central Junggar Basin, northwestern China: implications for hydrocarbon accumulation and preservation. Mar Pet Geol2023; 150: 106152.
