| Large quantity of the Permian-Triassic reef-shoal gas reservoirs have been discovered in Kaijiang-Liangping
trough, which is an important area for increasing reserve and production in the Sichuan Basin. However, there are many
dense reservoirs in deep strata more than 4 500 m in this area, so it is important to find fault-related "sweet spot"
reservoirs for efficient gas reservoir exploration and development. Based on the 3D seismic reprocessing and
interpretation of strike-slip faults, the structural characteristics of strike-slip faults are studied, and the reservoircontrolling
factors and favorable exploitation directions related to the strike-slip faults are analyzed combining with
drilling data. The results show that a series of NW-trending strike-slip faults are developed in Kaijiang-Liangping
trough. The strike-slip faults are mainly of vertical and flower-like faults in the section, and oblique and lateral faults in
the plane. There are multiple types of structures such as linear structure, en echelon structure, flower structure, horse-tail
structure, which are characterized by vertical stratification and planar segmentation. The strike-slip fault has small
displacement and low maturity, and has experienced the late Ediacaran-Early Cambrian, pre-Permian and Permian-
Triassic activities, and has the characteristics of linkage growth mechanism and inherited evolution. It is shown that
fractures are developed in strike-slip fault zone, and they subsequent increase carbonate rock’s permeability by more than
one order of magnitude, and fracture-related dissolution porosity by more than one time, which play an important
constructive role in carbonate reservoir. At the same time, the strike-slip faults not only form the dominant lateral
migration channels connecting to the Permian source rocks in the trough, but also may vertically connect the deep
Cambrian and Ordovician-Silurian source rocks to form multiple gas-bearing layers with the faults playing role of
transportation and accumulation. The study suggests that there is great potential for natural gas exploration and
development of the strike-slip fault-controlled gas reservoirs in the trough-platform margin and intra platform deep
carbonate reservoirs in the Kaijiang-Liangping trough, which are favorable new domain that are worthy of further
exploration and development in the Sichuan Basin. |
