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.