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The Fault Zone Architecture of Buried Reverse Faults in Sedimentary Basin: A Case From the Hong-Che Fault of Junggar Basin, China

Abstract

It is widely accepted that the faults can act as the conduits or the barrier for oil and gas migration. A lot of studies also confirmed that the fault zone is very complicated and composed of distinct components (Caine et al., 1996; Faulkner et al., 2010). Experimental studies indicated that different components of fault zone usually have different physical features, which can highly influence the migration of oil and gas along the fault. Nowadays, due to the restriction of data and methods, the studies of fault zone architecture are more focused on the field observation. In the petroleum exploration, what should be concerned is the buried faults in the sedimentary basin. However, this question is not cause enough attention in today's research. In order to solve this problem, we analysed the Hong-Che fault zone in the northwest margin of the Junggar Basin, Xinjiang Province, China. Combining with the seismic data, well logging data and drill cores of 104 wells, we set up a new method to analyse the architecture of buried faults. High-precision 3D seismic data reflect that the fault zone shows up as an obvious disturbed belt. The well logs that are sensitive to the fractures are used to fit a new logging curve, which can easily distinct the fault core and damage zone. The components of fault zone can be obvious observed in the drill cores, the fault core are composed of fault breccia, cataclasite, fault gouge, and the cracks in the damage zone are usually filled with calcite, quartz, clay and so on. Thin sections are used to observe the characteristics of cements in hydrothermal veins, and the analyses of fluid inclusions suggested that there are at least three stages of fluid activities in the Hong-Che fault zone. Systematic statistics suggested that there is an exponential relationship between the width of the fault core and damage zone of the reverse faults. This research can be very useful in analysing the architecture and development of fault zone of reverse fault.