Horizontal Wells and the Barnett Shale Play-Borehole Images Provide a Different Perspective

Larsen, L. Mark¹ (1) Schlumberger, Addison, TX

The Barnett Shale in the Fort Worth basin is being actively drilled to access unconventional natural gas resources. The Barnett Shale has long been an important source rock in north-central Texas. These resources are now being directly accessed though hydraulic fracturing techniques. Since inception, success in the Barnett has revolved around the development and evolution of new technology to extract gas from this very tight rock. A full analysis of the factors entering into the successful economic production of shale wells is often hindered by a lack of specific geological information.

Economic production depends on connecting as much surface area of the formation as possible to the wellbore without also connecting to bottom water. Many operators have turned to horizontal drilling, a technique that is providing good, but occasionally inconsistent results. The structure and stratigraphy of the Barnett shale varies throughout the basin. Borehole images allow the interpretation of geological features such as structural dip and the presence, type and orientation of fractures and faults, and also to predict the orientation of artificially induced fractures. Borehole images can help identify intervals of the lateral to target, or avoid, in the completion based on the presence, or absence, of observed geologic features.

This presentation introduces some concepts developed from a number of horizontal wells logged with micro-resistivity images. Borehole images can be used as an aid to understanding of the local geology and can help operators develop techniques to optimally place, complete and produce their wells.