Using Geological Expression to Extract Geohazards: An Example from the Barnett Shale, Ft. Worth Basin, Texas

Martin, Ryan; Halpin, Michael; Wooltorton, Thomas

One of the many challenges with the analysis and extraction of stratigraphic features is their often changeable seismic character throughout the feature's extent, and the degree of change can vary from subtle to extreme. We as interpreters can easily see these features within seismic data due to the strengths of the human visual perception system, but autotrackers and other data driven techniques struggle to cope effectively with a variable signal within one feature. Alternatively, a purely interpreter driven manual interpretation is subjective, time consuming, and fails to incorporate large amounts of information within the seismic data. The ability to use Geological Expression techniques to cope with these changes in seismic character in a data-driven manner but also allowing the user to ultimately control and influence the interpretation can improve the accuracy and the efficiency of the interpretation process.

This paper will explore the advantages of using Geological Expression techniques to extract geohazards which are complex in both their morphology and their seismic expression.

In the Barnett Shale, one key challenge is the proximity of the fracture zones to geohazards. Some of these geohazards include collapse structures, small-scale fault and fracture corridors, and laterally extensive carbonate zones that could influence production if they're water-bearing. As with many shale plays, a successful well largely depends on optimal well placement relative to existing fracture regimes and other geohazards. In the area of our study, the collapse structures which extent through the Barnett Shale are caused by underlying karst features. Both the karst and the collapse structures have complex geometries and implicit boundaries, making interpretation challenging. The use of seismic attributes, particularly Flexure and Chaos, helped isolate the features but did not identify the whole collapse structure due to the variability of the seismic expression within each structure, and relative to their surrounding stratigraphy. Conventional thresholding-based geobody techniques were therefore unable to delineate the full extent of the features. However, using the Adaptive Geobodies technique, we were able to combine both data-driven tracking and interpreter-guided geobody manipulation to extract these complex features in a rapid and accurate manner.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013