Seismic strategy for predicting highly profitable wells in the fractured-vuggy carbonate reservoirs

Abstract

Aiming at the problems of “high but unstable production” and low success ratio in highly profitable well prediction of the Ordovician fractured-vuggy carbonate reservoirs of the Tarim Basin, based on their features of small size, huge burial depth and high heterogeneity, and proceeding from the similar bead-like reflections, this study tries to find out and quantify the differences in oil and gas bearing scale between the reservoir units, and accurately works out the reserves in them. An integrated seismic technical strategy was proposed which bases on full-azimuth and high-density acquisition, centers on amplitude-preserved prestack depth migration, and stresses on the quantitative reservoir description. By figuring out the storage spaces of the fractured-vuggy reservoirs, the connection conditions between fracture-cave bodies, and the hydrocarbon bearing conditions of the fracture-cave bodies, the fracture-cave units which have larger reserves are chosen as drilling targets. The application results in Ha 7 area of the Tabei region proved that the fracture-cave bodies can be precisely studied and the fracture-cave units can be accurately delineated by these techniques, and the success ratio of the highly-profitable well prediction can be raised accordingly. Key words: carbonates, full-azimuth and high-density acquisition, prestack depth migration, quantitative reservoir characterization, Tarim Basin