WESCOTT, WILLIAM A., and KATRINA L. COTERILL
Amoco Exploration and Production, Houston, TX

Abstract: Imaging of Paleogeomorphic Features Using 3-D Seismic: Agony and Ecstasy

The extraction of seismic attributes from modern 3-D seismic data sets frequently allows geoscientists to image paleogeomorphic features in plan view with remarkable detail. Seismic attributes that are commonly used to image depositional and erosional features include: amplitudes, frequency, coherence, spectral decomposition, and neural network derived wavelet comparators. Unfortunately, not all techniques work equally well on all data sets. Optimum resolution of paleogeomorphology is frequently an iterative process requiring considerable trial and error. Successfully resolving depositional and erosional features on a seismic image, however, is not an end unto itself. Even after a depositional system is identified many questions remain. For example; in an incised valley, where are the sands? how are they distributed? are they in communication? Within a submarine fan are the sands in the channels, levee/overbank, or interchannel lobes? Where are the seal facies and where are they effective? Answering these questions and others requires an integrated approach. Methodologies include discriminating seismic facies on time and depth sections and comparing facies from vertical sections to various attribute maps; seismic modeling (rock property/AVO models, acoustic impedance, velocity analyses), and calibrating seismic response to well data when it is available. Although it is not a silver bullet, rigorous analysis of 3-D seismic, constrained by realistic geological models, has allowed geoscientists to make better and more accurate interpretations of lithofacies, stratal geometries and distributions, and depositional environments in the subsurface. These interpretations enable geoscientists to reduce technical uncertainty when exploring for and exploiting subtle, complex stratigraphic and combination traps.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas