碳酸盐岩古岩溶储层预测的难点与对策

在分析碳酸盐岩古岩溶储层成因特点与预测难点的基础上,确定针对该类储层进行地震预测的思路与对策,即首先建立古岩溶储层的地质概念模型,然后通过实验室地震物理模拟,确定敏感性地震参数,最后在井旁地震道属性统计分析的基础上,对塔里木盆地轮西区块奥陶系风化壳古岩溶储层进行预测.结果表明:该区早海西期存在2个岩溶旋回,相应地发育3套与岩溶作用有关的储层;平均反射强、均方根振幅、平均能量是反映缝洞型储层的主要敏感性地震参数,而能量半衰时斜率对于检测裂缝发育带最为敏感;研究区古岩溶储层的发育主要受岩溶地貌和断裂系统的控制,具有明显的分带性及叠置性特征.

Difficulty and countermeasures in carbonate paleokarst reservoir prediction

By analyzing genesis characteristics and prediction difficulties of carbonate paleokarst reservoir, the route and countermeasures of carbonate paleokarst reservoir seismic prediction were determined. A geologic conceptual model was first developed, and the sensitive seismic attribute parameters were determined by seismic physics modeling in laboratory. Finally, the reservoir distribution was predicted according to the statistics of near-well seismic traces attributes. The forecast results of the Odovician weathering curst karst reservoir in Lunxi block, Tarim Basin show that two karst cycles developed in the Odovician weathering curst of Lunxi block, which formed three sets of reservoirs related to the early Hercynian period karstification. The results of physical modeling show that the main seismic parameters sensive to the fractural and carvern reservoir are the average reflection intensity, the mean square root amplitude and the mean amount of energy, and the parameter sensive to the fractural zone is the gradient of energe half attenuation time. The distribution of paleokarst reservoir shows an obvious characteristic of banding and overlaying, which is mainly controlled by the karst topograph and the development of the faults.