缝洞型碳酸盐岩储集层高效井预测地震技术

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

针对塔里木盆地奥陶系碳酸盐岩缝洞型储集层"高产而不稳产"、高效井预测成功率低的难题,基于缝洞型储集层尺度小、埋深大、非均质性强的特征,从相似的地震串珠状反射入手,发现并量化储集单元之间含油气规模的差异,准确落实储集单元的含油气规模。提出了以全方位高密度地震采集为基础、叠前保幅深度偏移为核心、缝洞储集层量化描述为重点的一体化地震技术对策,通过落实缝洞体储集空间的大小、缝洞体之间的连通关系以及缝洞体的含油气性等关键问题,优选含油气规模较大的缝洞单元作为钻探目标。在塔北哈7井区实际应用结果表明,该方法能够实现缝洞体的精细研究和缝洞单元的准确划分,从而提高高效井预测成功率。

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 beating conditions of the fracture-cave bodies, the fracture-cave units which have larger reserves are chosen as drilling targets. The application results in Well 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.