碳酸盐岩小缝洞群储集体地震表征方法

Seismic Attribute Detection Method for Small Scale Fracture-cave of Carbonate Reservoir

塔里木盆地北部奥陶系储层为碳酸盐岩岩溶缝洞型储集体,储集空间尺度差异和结构变化大,非均质性强。随着勘探开发的不断深入,开发目标由大尺度溶洞向小尺度缝洞、孔洞集合体转移,以杂乱反射、连续波谷反射等地震反射特征为主的该类储集体的有效识别和精细表征是油田持续增储上产的关键。基于地震数值模型和物理模型模拟,针对小尺度缝洞储集体开展了多种地震表征方法的试算与地震属性敏感性分析;对于杂乱弱反射小尺度缝洞体,利用振幅曲率横向变化率属性能够较好地反映该类型缝洞储集体的空间展布;针对小尺度溶孔、裂缝型储集体,利用反射强度调谐累计频率衰减属性能较有效刻画储集体的边界轮廓。实际资料的预测结果与实钻井特征、成像测井资料相吻合,验证了小尺度缝洞储集体表征方法的有效性。

Ordovician reservoirs in northern Tarim Basin are carbonate karst fracture-cave reservoirs with large spatial scale differences,structural changes and strong heterogeneity.With the continuous deepening of exploration,the development target is transferred from large-scale karst cave to small-scale fracture cave and pore aggregate.The effective identification and fine characterization of such reservoirs,which are mainly characterized by random reflection,continuous trough reflection and other seismic reflection characteristics,is the key to the continuous increase of production.Based on seismic numerical simulation and physical model forward modeling,a variety of seismic characterization methods and seismic attribute sensitivity analysis were carried out for small-scale fracture-cave reservoirs.For the small-scale fracture-cave bodies with disordered weak reflection,the spatial distribution of this type of reservoir could be well reflected by using the transverse change rate of amplitude curvature.For the small-scale dissolved pore and fractured reservoirs,the reflection intensity tuning cumulative frequency attenuation attribute could be used to describe the boundary profile of the reservoir effectively.The prediction results of the actual data are consistent with the real drilling characteristics and imaging logging data,which verifies the effectiveness of the characterization method of small-scale fracture-cave reservoir.