High-Resolution Seismic Imaging and Reservoir Characterization for Drilling Risk and Production Management

Abstract

Abstract Often well planning, formation evaluation, reservoir engineering, andproduction management can ultimately be condensed to analyze and utilize thenature and spatial distribution of reservoirs and fluid properties. Thisobservation provides the motivation for this paper's objectives to:reviewthe impact of seismic resolution in imaging the reservoir, andexamine thechallenges and benefits of characterizing the reservoirs and fluid propertiesby integrating seismic, well, and engineering data at different measuringscales (resolutions) and sampling densities. Two real case studies for sand andcarbonate reservoirs are used to illustrate how a new high resolution techniqueaffects seismic image and elevates reservoir characterization beyond thetraditional resolution enhancement methods. Introduction The use of resolution enhancement techniques to improve the seismic image hasbeen part of the seismic industry almost since the origin of seismic signalprocessing. Geophysicists have used statistical deconvolution, signaturedeconvolution, spectral whitening, log-bases blueing, and log-based waveletshaping to better improve the seismic resolution, image the subtle geologicalfeatures, and evaluate the prospects. This paper begins with the theory of a novel resolution enhancement techniquein the continuous wavelet transform domain and its implementation methodology. Then it introduces a rigorous workflow to improve signal-to-noise ratio (SNR), velocity analysis, resolution, and anisotropic migration for better flattenedPSTM gathers, image, and prestack inversion. Finally, presents real casestudies for conventional and unconventional play types to illustrate how highresolution (HR) in seismic imaging and inversion improves the subsurface imagefor detailed stratigraphical and structural interrelation, reservoircharacterization, and production management. The two case studies are:complex Yegua sands with various thickness and spatial distribution fromlowstand deltas and slope fans in a shelf margin environment, andlowporosity Edward carbonate reservoirs from distal slope wackestones, reef andbank complexes, and back reef lagoonal deposits in a progradational sequence. Both studies are presented to show the holistic workflow of prestack dataprocessing, resolution enhancement, petrophysical evaluation, and prestackinversion. Theory: High Resolution Enhancement with Bandwidth Extension The bandwidth extension technique described here attempts to recover the lostwavelet characteristics from the available bandwidth in seismic data. Theavailable bandwidth acts as the fundamental frequencies, for which harmonicsand subharmonics are computed from and compared with the data, and then addedback to the wavelet by a convolutional-like process in the CWT domain. Thiseffectively reshapes the wavelet and broadens the seismic bandwidth. Any highharmonic and low subharmonics frequencies that do not match reflectivity in therecorded seismic data will not remain in the final result (Smith et al.,2008).