A Well Driven Processing Approach for Seismic Imaging of Subtle Traps

By

 Ahmed Abdou¹, Tarek Nafie², Ayman Shabrawi²

(1) Khalda Petroleum Company, Cairo, Egypt (2) WesternGeco, N/A, Egypt

 At present the choice of both processing sequence and seismic processing parameters relies on the skills and experience on the part of the processing analyst. Typically, processing parameters selection is performed by inspection and subjective judgment of seismic data processed through a variety of processing steps and parameters. However, examination of this conventional processing technique shows that it fails in many cases to provide a good tie with borehole seismic data, which in turn does not allow reliable interpretation of the seismic data. This paper demonstrates an alternative processing technique for integrating borehole data into the processing parameters selection from the earliest stage of the processing. The present processing technique is based upon (1) proper editing of the well acoustic data (sonic and density). The log editing is based on multi-log approach and is carried out interactively and by direct interaction between borehole and seismic data, and (2) quantitative and objective evaluation of the processing parameters selection obtained from the integration of borehole and seismic data by means of statistical attributes calculation of the extracted wavelets. These attributes values define both the best correlation between the well trace and the corresponding seismic trace and the complexity of the extracted wavelet. The present processing technique is illustrated with data from an oil field from the Egyptian Western Desert. Benchmark results have proven the superiority of seismic imaging results obtained by the present processing technique with respect to that obtained by the conventional processing. The present methodology offers two major advantages over the conventional processing approach. First, seismic data shows a better focusing of the fault shadows and more certainty of the fault pattern alignments. Second, it provided an improvement in the tie between the surface and the borehole seismic data so that events on the processed seismic data can be easily identified in terms of polarity and time.