China has yielded huge commercial production from the marine organic-rich shale but shows a slow exploration process in the lacustrine organic-rich shale. Multiple lacustrine shales in the Lower Jurassic of the eastern Sichuan Basin, rich in organic matters, are potential targets for shale hydrocarbon exploration and development. An investigation of the Dongyuemiao member, Lower Jurassic, was firstly conducted utilizing the macroscopic and microscopic analyses on outcrops and drilling cores to reveal the characteristics of sedimentary subfacies, mineral compositions, organic matter content and types, thermal maturity level, and reservoir quality. The dark shales in the Dongyuemiao member can be grouped into four general categories: shore, shallow, semi-deep, and deep lacustrine shales. The semi-deep and deep lacustrine shales generally have higher values in thickness (>20 m), average total organic carbon (TOC) content (>1.5 wt.%), and average porosity (>2%) relative to shore and shallow lacustrine shales. All four categories of shales primarily consist of type II kerogen and have thermal maturity levels exceeding the vitrinite reflectance value of 0.9–1.0% (or the T_max of ∼440°C). Thermally powered pore generation generally promoted the pore system as indicated by the positive correlation between porosity and T_max. Notably, the semi-deep lacustrine shale in the vicinity of the Qiyueshan Fault Zone shows abnormally high porosity and low oil saturation index (OSI) at T_max>∼465°C potentially due to the promoted hydrocarbon expulsion through multiscale fractures. Except for the vicinity of the Qiyueshan Fault Zone, the semi-deep and deep lacustrine shales generally show the better exploration prospect relative to the shore and shallow lacustrine shales. Additionally, the high content of clay minerals (>40 wt%) reduced the brittleness of the semi-deep and deep lacustrine shales which may challenge the artificial hydraulic fracturing.

The Rongchang–Dazu region in western Chongqing (eastern Sichuan Basin, China), known for its seismic activity, is a promising area for deep geothermal resource development; however, practical development is limited. Key geological understandings, such as heat flux, geothermal gradients, the nature of heat sources, thermal reservoir rock characteristics, and the classification of geothermal resources, remain in need of further study. In this work, the targeted area is surrounded by Sinian–Cambrian carbonate gas fields. An analysis of the deep geothermal prospects was conducted using exploration and development data from the Gaoshiti–Moxi gas fields within the Longwangmiao and Dengying Formations. The results indicate that the Rongchang–Dazu area has relatively high heat flow values and geothermal gradients within the Sichuan Basin, correlating with fault structure and seismic activity. Gas test data confirm that the Longwangmiao Formation in the study area reaches depths of 4000 to 4500 metres and exhibits anomalous pressures and temperatures exceeding 140 °C. Meanwhile, the Dengying Formation of the Sinian system lies at depths of 5000 to 5500 metres, with normal pressure, minimal water production, and temperatures exceeding 150 °C, characterising it as a dry-hot rock resource. Adjacent to western Chongqing, the Gaoshiti area within the Longwangmiao Formation, with an estimated flow rate of 100 kg/s, shows that the dynamic investment payback period is significantly shorter than the estimated 30-year life of a geothermal power plant, indicating strong economic viability. Deep geothermal resource development aids in conserving gas resources and enhancing the energy mix in western Chongqing. Future research should prioritise understanding the links between basement faults, seismic activity, and heat flow dynamics.

This work aims to explore the Lower Silurian shale gas and tight sandstone gas accumulation conditions in the Gongtan Syncline, southeastern Sichuan Basin. The sedimentary environment, organic geochemical characteristics, reservoir characteristics, gas content, and preservation conditions of the reservoir were comprehensively analyzed. The results show that the Wufeng–Longmaxi Formation shale formed in a deep-water shelf characterized by a large thickness (50–70 m), appropriate total organic carbon content (0.5–5.47%), high maturity (2.38%), high brittle mineral content (67.10%), and large gas content (0.71–1.64 m³/t), and the formations show the good resource potential of the shale gas. The Xintan Formation formed in a lower shore phase, and the tight sandstone is locally developed with a small thickness. The Xiaoheba Formation formed in an upper-middle shore phase, and the tight sandstone is stably distributed with large thicknesses. The porosity and permeability of the two sets of sandstone are small and some natural fractures are developed in the sandstone, but the fracture filling degree is higher. The results of well logging show that there are abnormally high values of total hydrocarbon in both the Xintan Formation and Xiaoheba Formation; this indicates that tight sandstone gas is developed in the Lower Silurian strata. A comprehensive study indicates that the Lower Silurian of the Gongtan Syncline has the geological conditions for the formation of shale gas and tight sandstone gas, which are the “Two gases” with good co-exploration prospects.