全方位偏移成像技术在塔河碳酸盐岩储层中的应用

Application of full-azimuth migration imaging to carbonate reservoirs in the Tahe Oilfield

常规地震数据处理技术无法充分利用宽方位地震数据所包含的方位角信息。针对塔里木盆地塔河油田某区块的实际宽方位地震数据,基于全方位偏移成像技术,利用全方位共反射角道集对研究区碳酸盐岩储层的小断裂进行了精细成像,并将偏移道集、成果剖面和地震相干属性与OVT技术的偏移结果进行了对比和分析;同时,对全方位倾角道集进行了绕射波分离成像,并对比分析了绕射波分离前、后的成像剖面和地震属性。结果表明,全方位共反射角道集的信噪比更高,对应的剩余延迟时谱的能量团更聚焦,该道集在全方位和分方位角范围内的成像剖面对小断裂的刻画更精细,断裂面更清楚,断点更干脆;绕射波成像剖面能有效提高溶蚀孔洞的识别精度,与绕射波分离前的成像剖面相比,其响应特征更明显,分布范围更广,溶蚀孔洞之间的区分度更高。

Information on full-azimuth seismic data is not retained by conventional seismic data processing methods.In this study,the potential of exploiting such information was evaluated in the Tahe Oilfield.Based on the full-azimuth migration imaging method,reflection gathers were used to form high-resolution images of the small fractures in the carbonate reservoirs.The migration gathers,resultant profiles,and attributes of coherence were compared with the migration results of the offset-vector tile (OVT) method.The diffraction waves were separated from the directional seismic gathers.Then,the imaging profiles and seismic attributes before and after the separation were compared and analyzed.The results showed that the full-azimuth reflection gathers had a higher signal-to-noise ratio compared with the OVT gathers.Moreover,the energy groups of the corresponding residual delay time spectra were more focused.Full-azimuth imaging has been shown to describe small faults more precisely and provides clearer fracture points and surfaces.Imaging profiles based on diffracted waves can improve the identification accuracy of caves as they are characterized by clearer profiles,wider distribution ranges,and a higher power of discrimination.