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Structural Attribute Analysis Used in Barnett Resource Development

Mitchell, Gary C.1; Berge, Timothy B.2
1 Rimrock Energy L.L.C., Denver, CO.
2 Pangean Resources, Denver, CO.

Successful completions in the shale of the Barnett Formation require a combination of high quality geology and geophysics in association with high technology drilling and completion engineering. Large areas of the Barnett play contain challenging conditions that make economic completions more difficult. These challenges can be geological (faulting and karsting), geophysical (gas effects and velocities), and engineering (Barnett thickness and lack of frac barriers). Thus the majority of the play area has more difficulties to overcome than in the core area (sweet spots) and requires the use of higher technology with respect to the geosciences and engineering. Success is not simply a matter of drilling a large number of wells into a uniform resource (as mistakenly applied to the Barnett), but one must both avoid drilling marginally or non-economic wells and drill more wells with significantly higher economic returns.

Important aspects related to the geology and geophysics for the drilling of successful Barnett gas wells are:

● Prediction and avoidance of Ellenberger karsts and both large and small scale faults that provide vertical conduits for water.

● Ability to define an objective zone within the Barnett and to maintain penetration within that zone.

● Ability to define “lateral” facies changes within the Barnett that may require different frac techniques from one zone to another.

● Improved frac designs to better contact the Barnett more efficiently.

● Anticipate conduits between wells to reduce problem communication.

We use detailed structural analysis and multi-attribute interpretation of 3D seismic data to aid in the drilling program. Karsts and major tectonic faults, both development hazards, are easily seen in dip-steered Similarity and Curvature attributes. The mid range of the Moat Negative Curvature attribute shows a fine network of anomalies that can be correlated to natural fracture trends and small faults, and that these are activated and accessed by fracture stimulation during well completions. Comparing micro-seismic fracture monitoring and visualization of the seismic derived structural attribute volumes shows a clear relationship that allow us to predict reservoir presence as well as hazards. Clearly this is a broad multidisciplinary workflow that requires expertise from area of Geology, Geophysics, and Engineering that is somewhat unique to the play.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009