A New
Approach to Seismic
Interpretation
in Challenging Imaging Environments
C. Edward Helsing and David C. Berman. ExxonMobil Exploration Company, 222 Benmar Drive, Houston Texas 77060 [email protected]
A seismic
image adjacent to a complex velocity anomaly such as a salt
body comprises reflections resulting from multiple ray-path types. Despite
application of multipathing algorithms such as Wave Equation PSDM, the
full-stack
seismic
data
generally exhibit low signal to noise ratios allowing
for multiple valid structural interpretations. We present a new approach to
this common
interpretation
problem.
Recent advances in computing now allow commercial production of Wave
Equation PSDM subsurface-angle gathers, which are used for residual velocity
updates. Taking the next step and stacking subsurface-angle gathers provides
the interpreter with a new way of viewing seismic
data
, in which partial stacks
are defined as a function of subsurface angle rather than the familiar surface
offset or angle. This distinction is important because subsurface-angle stacks
more often efficiently separate signal from noise compared to surface offset or
angle stacks. The reason for this is, given a point in the volume, a dip, and a
reflection angle, the ray paths from a given source and receiver to the image
point are uniquely defined. This is not true for surface-offset
data
in a
multipathing situation.
The presentation describes an interpretation
technique that utilizes 3D
visualization, which allows the interpreter to efficiently integrate
subsurface-angle stacks with
seismic
and non-
seismic
datasets to discriminate
between valid alternative structural interpretations.
Additional applications of this technique include imaging beneath velocity anomalies related to shallow gas, large discovered gas fields, or anomalous channel fill within the overburden.
AAPG Search and Discover Article #90067©2007 AAPG Mid-Continent Section Meeting, Wichita, Kansas