论文详情
随着塔河油田勘探开发程度的进一步深入,对缝洞储集体空间位置成像的准确度和小尺度缝洞成像精度提出了更高的要求,常规叠前时间偏移成像技术已经很难满足需求。为此,建立了分频叠前深度偏移成像技术流程。首先,根据实际地震和地质资料特征,设置不同频宽的滤波器;其次,对叠前CMP道集进行分频处理,得到高、中、低不同频段的CMP道集数据体;最后利用克希霍夫叠前深度偏移技术,对不同频段的CMP道集分别进行偏移成像,从而得到与之相对应的不同频段叠前深度偏移数据体。塔河地区某工区实际三维地震资料应用结果表明,与叠前时间偏移后分频技术的应用结果相比,分频叠前深度偏移成像技术明显降低了叠后分频技术带来的“假频、‘串珠’纵向拉长”的假象,不但提高了缝洞体空间位置成像的准确度,同时提高了地震资料的分辨率,利用高频段叠前分频深度偏移数据体能够识别更小尺度缝洞体,且缝洞成像结果与实际钻井结果吻合。该技术在塔河地区具有较大的应用前景。
With advances in exploration and development in the Tahe Oilfield,the accuracy of spatial location imaging of fracture-cavity reservoirs and small-scale fracture-cavity imaging needs to be enhanced.These requirements are difficult to achieve using conventional prestack time migration imaging.To address this issue,a frequency-division prestack depth migration imaging method was proposed,and is illustrated in this paper.The first step of the method consists of implementing filters for different frequency bands according to the frequency content of the actual data.Then,frequency division processing is conducted for the original prestack common mid-point (CMP) gather as to generate three different CMP gathers containing the high,medium,or low frequency bands.Finally,depth migration for the three CMP gathers is conducted using Kirchhoff prestack depth migration to obtain the data volumes corresponding to the three bands.The practical application of the developed technique on three-dimensional seismic data in the Tahe oilfield showed that compared with the post-stack frequency division time migration technology,the proposed method can reduce the Gibbs effect and improve the imaging accuracy of the spatial position of fracture-cavity reservoirs as well as the resolution of seismic data.Using a high-frequency prestack depth migration data volume,a small-scale fracture-cavity reservoir could be identified,and its characteristics were consistent with those found by actual drilling.The authors believe that the proposed method has the potential for application in the Tahe area.
国家油气重大专项(2016ZX05014001)资助。