Technique and application of fracture detection in fracture-cavity reservoirs in Yingshan Formation, Yubei area, southwestern Tarim

The geological characteristics of the reservoirs in the Ordovician Yingshan Formation in the Yubei area of the southwestern Tarim Basin showed that fractures controlled the development of karst reservoirs. Seismic fracture detection technology was significant for carbonate reservoir prediction. The combination of four kinds of crack detection technology was adopted in this paper. (1) Dip azimuth attribute was used to recognize large-scale fractures and faults. (2) Curvature technique was adopted to identify cracks resulted from the structural bending deformation of formations. (3) Fine coherence technology was used to accurately identify stratigraphic discontinuity and small-scale rivers. (4) Spectrum decomposition technique was effectively introduced into the tracking technology to predict tectonic shear and expansion cracks resulting from structural deformation extrusion. The results showed that, in addition to the area near the fault zone, micro-cracks were also widely developed in the zone which was away from the fault zone. This is consistent with the long term tectonic compression background and the fracture development features revealed by wells and cores, and shows that the technological combination method was effective to detect the fracture development zone.