Welcome to visit Geoscience!

Geoscience ›› 2025, Vol. 39 ›› Issue (04): 884-897.DOI: 10.19657/j.geoscience.1000-8527.2025.017

• Tectonic Geology • Previous Articles     Next Articles

Characteristics of Permian Strike-slip Faults in Central Sichuan Basin and Their Significance for Hydrocarbon Accumulation

TANG Hao1(), WU Guanghui1, MA Bingshan1,*(), HUANG Tianjun2, ZOU Yu2, LAN Xuemei2, SU Chen2, WANG Jiamu1   

  1. 1. Schoolof Geoscienceand Technology, Southwest Petroleum University, Chengdu, Sichuan 610500, China
    2. Exploration and Development Research Institute of Southwest Oil & Gasfield Company, PetroChina, Chengdu, Sichuan 610041, China
  • Online:2025-08-10 Published:2025-08-27
  • Contact: MA Bingshan

Abstract:

Recent studies have revealed the presence of large-scale strike-slip faults in the central Sichuan area within the Sichuan Cratonic Basin, which makes it a promising new region for the exploration and development of fault-controlled oil and gas reservoirs. Drilling results indicate that a series of high-yield wells in the Permian of the Gaomo area in central Sichuan bear a certain spatiotemporal correlation with the distribution of strike-slip faults, confirming a close relationship between strike-slip faults and gas reservoirs. However, the characteristics of strike-slip faults and their interaction with gas reservoirs remain unclear, hindering the exploration and development of gas reservoirs in the central Sichuan area.Based on 7,066 km2 of contiguous 3D seismic data and typical well data from the Gaomo area, this study analyzes the basic characteristics of weak strike-slip faults in the Permian and their controlling effect on gas reservoirs, providing a case study for research on fault-related hydrocarbon accumulation under weak strike-slip fault activity.The results show that there are eight first-order strike-slip faults developed in the Permian of the Gaomo area, with strikes of NEE, EW, and NW, and lengths ranging from 30 to 160 km. The spacing between first-order strike-slip faults is 10 to 30 km, and the Permian strike-slip faults are basically inherited from the Cambrian faults. Statistical analysis of the throw of the 8 major strike-slip faults suggests weak activity. The activity intensity of the Permian strike-slip faults in central Sichuan exhibits regional differences, with an overall pattern of being stronger in the north than in the south and stronger in the east than in the west. Both the distribution and intensity of strike-slip faults at the base of the Lower Permian are greater than those at the base of the Upper Permian.The Permian strike-slip faults may have undergone left-lateral extensional-tensional activity controlled by the Emei Taphrogenesis. The Permian strike-slip faults in the Gaomo area display obvious segmentation, with structural styles mainly being simple ones such as en echelon, linear, and oblique. The segmentation of strike-slip faults leads to differences in fault structural characteristics and petrophysical properties of fault zones, exerting a significant impact on fault permeability and hydrocarbon migration and accumulation. Logging results show that within 2 km of the core of a single well’s strike-slip fault, porosity and permeability tend to improve significantly, which may be controlled by the fracture network of the strike-slip fault. A series of drilling data indicates that the closer to the strike-slip fault, the higher the hydrocarbon production, confirming the controlling effect of strike-slip faults on hydrocarbons.Anatomical analysis of single-well gas reservoirs confirms that strike-slip faults have three types of favorable hydrocarbon accumulation effects and two types of destructive effects on accumulation. Fault-lithology binary hydrocarbon accumulation is the main development model of Permian gas reservoirs. The favorable strike-slip fault-related accumulation models include vertical connection between faults and source rocks, vertical migration and accumulation through faults with upward migration pathways, and bilateral clamping by faults with bidirectional migration pathways. However, multi-stage faulting activities of strike-slip faults may directly damage oil and gas, and the structural characteristics of strike-slip faults-small throws in the deep part and large throws in the shallow part-also have a destructive effect on hydrocarbon accumulation.

Key words: strike-slip faults, Permian System, structural characteristics, hydrocarbon accumulation model, Gaomo Area, Sichuan Basin

CLC Number: