Seismic facies analysis: Past, present and future

Abstract

Seismic facies and lithofacies analysis, once considered a breakthrough in exploration applications, is currently a dynamic field because of the addition of several new concepts and interpretive procedures. In terms of basic theory, notable developments have taken place that encompass refinements in geological and geophysical concepts, including several enhancements to sequence-stratigraphic and facies distribution models, better knowledge of seismic response mechanism to small-scale stratigraphic structures and different rock types, as well as the emergence of new technologies, such as the one allows the restoration of original depositional architecture and spectral decomposition. A seismic facies analysis index system is proposed that includes nine independent parameters: position, external form, internal configuration, continuity, smoothness, amplitude, frequency, special waveforms, and appearance. The sedimentary systems established by traditional seismic facies analysis lack detailed lithofacies and hydrodynamic information. However, presently further subdivision of seismic lithofacies into more detailed categories is now possible, made available by the addition of new seismic parameters that are indicative of sedimentary structure and rock-type combinations. This enables interpreters to identify lithofacies details directly from the seismic data and reconstruct the sedimentary systems with greater precision (by superposition of the environment, lithofacies and flow paths). The seismic slice image analysis, including seismic geomorphology and seismic sedimentology, employs a stratal time slice, 90° phase shift, and spectral decomposition techniques to improve the resolution of the slice images, describe sedimentary micro-facies and understand sedimentary processes based on the geometric features of the time slice. The seismic facies auto-classification techniques are still at an early stage of development, but significant possibilities exist for future enhancements if the new seismic index system, where the accumulated knowledge of the skilled experts could be utilized advantageously. This paper will also serve as a summary of the state-of-the-art of seismic facies analysis.