地质科技通报 (Jul 2022)
Seismic attribute characteristics of an ultradeep fractured-reservoir in the northern section of Shunbei No.5 strike-slip fault zone in Tarim Basin
Abstract
The Shunbei No. 5 strike-slip fault and its associated fractures in Tarim Basin control the formation of reservoirs and impact the migration and accumulation of oil and gas. Selecting appropriate seismic attributes to characterize and describe the spatial distribution of fractured reservoirs plays an important role in fractured reservoir prediction. Due to the seismic resolution of faults and fractures at different scales, it is necessary to use different methods and their combinations to identify fractures at different scales. To further characterize the fractures that associated with strike-slip faults in the Shunbei area in Tarim Basin, this paper compares the capability characterizing faults and fractures of individual seismic attributes and their combined attributes.The seismic attribute comparison shows that the high-precision coherent volume that constrained by dip angle and plane feature attribute can characterize the large-scale faults with fault distances over 40 m.The multi-coherent merge and strain-energy attributes can represent mesoscale fractures with a fault distance of 40-15 m. In addition, fracture-gave gain and thin likelihood enhancer can characterize small-scale fractures with a fault distance less than 15 m.The results of correlation fitting of typical seismic attributes to actual fracture data and fracture density curves that interpreted from EMI imaging logging were ranked.Finally, four seismic attributes including chaos, planes, third component of structural tensor, and frequency division coherence fusion are optimized for fracture density calculation.The calculated results show that the potential reservoirs that associated with the high-density fracture zone is mainly located within 1.5 km of the transpression section of the fault in the upper section of the lower to middle Ordovician Yingshan Formation.
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