Detection and interpretation of fracture sets in tight sandstone reservoir
HE Jian-jun, HE Zhen-hua, HUANG Dei-ji (State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, China)
The Reservoir T51 of second member of Xujiahe Formation, Upper Triassic(T_3x~2) in Sichuan Basin is an important oil-gas reservoir. It is composed of deep buried sandstone with zones rich in fractures. As those zones are the most favorable for oil-gas accumulation or migration, so people need to detect and distinguish the zones rich in fractures from 3D seismic data. However, to detect and identify those fracture zones from seismic data are very difficult by using the traditional methods, because the seismic attribute anomalies may be caused both by fractures or lithologic changes. To solve those problems, the authors first identify the channel sandstone formation by sedimentary microfacies analysis, then, employ the method of GHT (Generalized Hilbert Transform) to detect all possible fractures information in channel sandbodies on seismic horizontal slices, and at last, use the comprehensive data including geological, drilling, well-log and seismic data to determine the most possible zones rich in fractures. The real data processing results show that the above idea and techniques are useful to predict the zone rich in fractures in tight reservior.