Differential deformation of a strike-slip fault in the Paleozoic carbonate reservoirs of the Tarim Basin, China

Abstract

Ultra-deep carbonate reservoirs buried over 7000 m are distributed around strike-slip faults, which control hydrocarbon accumulation and enrichment in the Tarim Basin, China. This study proposes a fracture development index (FDI) method for analyzing the width of the strike-slip fault zone based on 3D seismic data. Based on the FDI method and geological and geophysical data, we analyze the structural characteristics of the SB5 strike-slip fault and the scaling of fault zone width and throw.In map view, at depth the strike-slip fault is characterized by single fault segments, extensional overlaps, and contractional overlaps, at intermediate depths by left-stepping en echelon normal faults, and in shallow layers by right-stepping en echelon normal faults. In cross section, we find composite flower structures and positive flower structures and medium-shallow layer negative flower structures or deep layer negative flower structures and medium-shallow layer negative flower structures. The formation time of deep, middle, and shallow layer faults is the middle Caledonian, Late Caledonian, and Late Hercynian. The heterogeneity of the strike-slip fault zone varies from strong to weak from contractional overlaps, to extensional overlaps, and single fault segments. Strike-slip fault-related fractures are dominated by three sets intersecting with strike-slip faults at small angles. Where throw is less than 100 m, the fault zone width and throw have a good power law relationship. Where the throw is over 100 m, the width tends to diminish with throw.