The life cycle of a seismic data volume can be broken into three parts: acquisition, processing, and interpretation. Accomplishing each of these steps requires the application of a different set of skills and techniques to accomplish. Of the three, data acquisition and processing are the most expensive steps to perform. Data acquisition is a time and equipment intensive operation. Processing the seismic data, after acquisition, is a computationally very expensive procedure; usually performed on very large computer clusters. However, the most time consuming of these steps is the interpretation of the seismic data. Arguably, this is also the least optimized part of the volume life cycle, as certain aspects of interpretation are still performed largely by hand. Efficiency gains are ongoing in the fields of seismic acquisition and processing (especially migration). Initial steps have also been made in the semi-automation of interpretation, but much work remains to be done. Semi-automatic interpretation holds the greatest promise for quickly improving the value of the seismic volume acquisition and utilization cycle.
This dissertation concentrates on the development of new techniques to aid the human interpreter in their interpretation of 3D seismic volumes. The ability to both accelerate and improve interpretation of geology in a data volume is a significant goal for increasing the value realized from a given data set. Particular attention is given to two of the more intractable problems in seismic data interpretation: salt-body delineation, and the interpretation of stratigraphic features. The difficulties inherent in each task are different, but both tasks are quite time consuming when performed largely by hand.
This dissertation is comprised of five parts. Part 1 describes Voxel Density, a novel volume processing technique that can be used to filter, or improve the contrast in a data set. This technique uses the local persistence of features in the data set to control filtering, rescaling, and smoothing operations. Linking the application of these operations to local data configuration makes these processes edge-preserving, and improves their performance.
Part 2 is a description of a workflow to highlight and interpret the edges of a salt body using new volume processing techniques. Salt boundary reflections are highlighted by isolating locally high amplitude reflections and filtering noise from the resulting sparse data volume. This isolation of salt reflections enables the application of pre-existing semi-automated interpretation techniques to the complex problem of salt interpretation.
Part 3 is a description of Domain Transformation, a process to re-sample a seismic volume to create a volume of paleo-depositional surfaces. Interpreting channels, and other stratigraphic features, is much easier using this volume of paleo-depositional surfaces. Dip, and the vertical component of fault offset is removed from the volume using this procedure.
Part 4 discusses the application of cloth simulation to correct for the horizontal component of fault offset in a Domain Transformed data volume. Cloth simulation, a technique adapted from Computer Graphics, is used to evenly distribute fault deformation throughout a data set. This procedure produces an output Stratal domain volume with no null zones, enabling the calculation of volume attributes in the fully-flattened Stratal domain.
Part 5 reiterates the major conclusions of each previous section and goes on to discuss potential avenues of future research. A variety of possible solutions to problems encountered and shortcomings of the existing techniques are described with a brief discussion of the likelihood of success for each of these new topics of research.
The overarching research question being addressed by these five sections is: “To what degree is it possible to utilize modern computer processing to aid the largely manual interpretation of 3D seismic volumes?” This question stands for both oil exploration and non-oil exploration applications (such carbon sequestration). To answer this question, it was necessary to bridge the world of geology and geophysics with the world of computer science. As a result, a variety of potentially unfamiliar terms and concepts are discussed. To aid the reader, a Glossary of Terms has been included at the end of the dissertation.