Strike-slip fault System and its reservoir-controlling rules in Awati-Manger-transitional area, Tarim basin

A large numbcr of strike-slip faults with small displaccmcnt are developed in the transition area between Awati and Mangar depressions in Tarim basin. These faults cut the sedimentary covcr of diffcrcnt ages from the basement upwards, and controlled the development of fracture-vuggy hydrocarbon reservoirs in the Paleozoic carbonates, becoming an important target for oil and gas exploration and development in the abdomen of the Tarim basin, and also a hot spot in the study of structural deformation and controlling-reservoir in the Tarim basin in rcccnt ycars. Bascd on the rcsults of 3D seismic data Interpretation, this paper analyzes the structural characteristics of strike-slip fault System and its internal relationship with the distribution of fracture-cavity reservoirs in the Awati-Mangar transition area. The research shows that: ® The strike-slip fault has different scale permeability distribution characteristics in the Ammanian transition zone. From the bottom to the top, it can be dividcd into three tectonic deformation layers, namcly deep tectonic deformation layer (below TG2), middle tectonic deformation layer (T€3-T02) and shallow tectonic deformation layer (T()3-TD). On the plane, it can bc dividcd into four deformation zoncs, namely, southern slope of Tabci (Northern Tarim) Uplift, western slope of Mangar sag, eastern slope of Awati sag and Tazhong uplift. The structural styles of strike-slip faultin sections are diffcrcnt in deformation layers and deformation zones, and the structural combinationsin plane are also diffcrcnt. In general, it constitutes a complex strike-slip fault System. (2) The strike-slip fault System in the Awati-Mangar transition area is the result of superimposed tectonic deformation of multiple periods, and its formation and evolution proecss can be broadly dividcd into thrce tectonic periods: Middle and Late Cambrian, Middle and Latc Ordovician and Siluran-Carboniferous. The activity modes of the samc fault are different in different tectonic periods, and the activity modes of different deformation zones in the same period are also diffcrcnt. In general, strike-slip shear displacement predominates. (3) The structural geometry and kinematie characteristics (active period and deformation degree) of the strike-slip fault zone significantly control the development of Paleozoic fractuke-eavity reservoirs, and high-quality fractuke-eavity reservoirs are distributed along thosc parts with large seale, significant strike-slip deformation and high paleostructural location in the Middle and late Ordovician. The location change of the main displacement belt, local oblique tension, displacement reduetion or change of a single strike-slip fault are beneficial to the development of fracture-vavity reservoir group, and lithology and local structural combination control the formation of fracture-vavity reservoir. © 2024 Geological Society of China. All rights reserved.