The largest Precambrian gasfield in China has been found in the central Sichuan Basin. It has been assumed as an Ediacaran (Sinian) mound–shoal, microfacies-controlled, dolomite reservoir. However, the extremely low porosity–permeability and heterogeneous reservoir cannot establish high production by conventional development technology in the deep subsurface. For this contribution, we carried out development tests on the fractured reservoir by seismic reservoir description and horizontal well drilling. New advances have been made in recent years: (1) the prestack time and depth migration processing provides better seismic data for strike-slip fault identification; (2) seismic planar strike-slip structures (e.g., en échelon/oblique faults) and lithofacies offset together with sectional vertical fault reflection and flower structure are favorable for strike–slip fault identification; (3) in addition to coherence, maximum likelihood and steerable pyramid attributes can be used to identify small strike-slip faults and for fault mapping; (4) fusion attributes of seismic illumination and structural tensor were used to find fractured reservoir along fault damage zone; (5) horizontal wells were carried out across the strike-slip fault damage zone and penetrated fractured reservoir with high production. Subsequently, a large strike-slip fault system has been found throughout the central intracratonic basin, and the “sweet spot” of the fractured reservoir along the strike-slip fault damage zone is widely developed to be a new favorable domain for high-production development. There is still a big challenge in seismic and horizontal well technology for the economical exploitation of the deep fractured reservoirs. This practice provides new insight in the deep tight matrix reservoir development.

The largest Precambrian gas field in China has been found in the central Sichuan Basin. It is assumed as a mound-shoal microfacies-controlled dolomite reservoir. Recently, a large strike-slip fault system has been identified in the gas field that needs further study of its effect on the Ediacaran reservoirs for highly efficient exploitation of the gas field. For this contribution, we study the matrix reservoir and fractured reservoir along the strike-slip fault damage zones by the cores, FMI (Formation MicroScanner Image) and logging interpretation data, seismic description and production data. It has shown that the matrix reservoir is tight (porosity less than 3%, permeability less than 0.5 mD) that cannot support economical production by conventional exploitation technology in the deep subsurface. On the other hand, the porosity and permeability of the Ediacaran fractured reservoirs could be increased more than one time and 1–3 orders of magnitude. Except for a few localized fracture zones, the fracture elements and fractured reservoirs show a paw-law distribution with the distance to the fault core. Furthermore, the fault effect is more favorable for the increase in the porosity and permeability of the matrix reservoir in the intraplatform than in the platform margin. The overlapping of mound-shoal microfacies, fracturing and karstification could result in large-scale “sweet spots” of the fractured reservoirs in the fault damage zone. The “sweet spot” of fractured reservoir in the fault damage zone is a new favorable exploitation target in the deep central Sichuan Basin.

Determining the timing of hidden faults that terminate beneath the subsurface remains a significant challenge. For this contribution, seismic fault interpretation, fracture diagenesis analysis, and U-Pb dating of fracture cements are integrated to constrain the activity of hidden thrust faults in the southeastern Sichuan Basin. The results show that the EW- and NW-trending hidden thrust faults developed in the Permian, while the NE-trending faults have inherited later fault activity till the Cenozoic. The hidden thrust fault propagates upward from the top of the Upper Permian to the Lower Triassic strata. Fault inversion within the Permian is firstly identified by the thickness variation between the two fault walls. Core-based fracture diagenesis analysis indicates that multiple fractures and associated dissolution porosity developed within the tight matrix reservoir. In situ U-Pb dating of fracture cements yields ages of 247.4 ± 2 Ma and 234.8 ± 9.1 Ma, indicating that the hidden fault activity predates the Early Triassic. The absence of strata, evidence of structural uplift, and fault inversion collectively suggest that the first faulting in the eastern Sichuan Basin occurred at the end of the Middle Permian. The findings highlight that fracture–cave reservoir along the hidden thrust fault zone has been controlled by the coupling of the fracturing and karstification at the end of the Middle Permian, and is the key target for high gas production.

A large strike-slip fault system has been found in the central Sichuan Basin, although its effects on the pre-Mesozoic tight dolomite gas reservoirs in the deep (>4500 m) subsurface are uncertain. By integrating 3D seismic fault mapping, detailed fracture characterization, and well production data, this study demonstrates that strike-slip faults are extensively developed as vertically stratified arrays within the Ediacaran, Cambrian, and Permian dolomite intervals. These faults connect Lower Cambrian source rocks to multiple reservoir horizons, thereby establishing both lateral and vertical hydrocarbon migration pathways. A defining element of this system is the spatiotemporal coupling of “source-fault-reservoir,” which underpins the formation of a large-scale, pre-Mesozoic fault-controlled gas accumulation. Seismic evidence shows that many of these faults exhibit near-vertical geometries, en echelon arrangements, and step-over structures, all of which foster intense fracturing in the adjacent dolomites. Such fracturing substantially enhances porosity and permeability, yielding localized “sweet spots” with improved storage capacity and fluid flow properties, particularly within slope areas where structural conditions favor gas trapping. Production data strongly corroborate the geological and seismic observations, with wells that intersect or closely adjoin these fault zones typically exhibiting higher flow rates and more stable production profiles. This phenomenon highlights the pivotal role of fault-induced fractures in reservoir performance and underscores the need for detailed fault mapping and fracture network analysis in deep, tight carbonate plays. Furthermore, the recognition of this large-scale, strike-slip fault-controlled dolomite reservoir in a deep intracratonic setting underscores its considerable exploitation potential and points to broader implications for petroleum geology. Consequently, this study provides a robust framework for understanding the interplay between fault architecture and reservoir quality, offering valuable insights for guiding future exploration and development in analogous deep carbonate basins worldwide.Key words: Strike-slip fault; Deep tight dolomite reservoir; Strike-slip fault-related petroleum system; Migration and accumulation; Exploration; Sichuan Basin