Use of Horizontal Well Image Tools in the Completion of Barnett Shale Wells

George Waters
Schlumberger, Oklahoma City, OK

Horizontal wells represent a growing percentage of the drilling activity in low permeability reservoirs within the United States. In order to achieve optimum horizontal well stimulation, the lateral section must be characterized and the perforation placement customized to account for reservoir changes along the wellbore. In most cases evaluation is limited to a gamma ray measurement while-drilling tool and, periodically, a mud log. While these tools can identify significant structural changes and hydrocarbon shows along the lateral, they provide little stratigraphic information, no natural fracture information, and no stress information.

One log evaluation tool that is being used more frequently in horizontal wells is the formation imager. It produces electrical images of the borehole that provide detailed structural information such as faulting and natural fracturing. The images can also be used to estimate the stress state along the lateral via the presence and orientation, or absence, of drilling induced fractures. With this information important completion decisions can be made such as: lateral isolation need, stimulation staging requirements, perforation cluster design and spacing. Images can also identify offset well hydraulic fractures when they are intersected. This too can drive perforating and completion strategies, as well as future infill well placement.

This presentation demonstrates how formation images have been used to implement changes to the perforation placement and stimulation staging in horizontal Barnett shale wells. In addition, actual stimulation pressure responses and microseismic activity are compared to those predicted from image logs. Infill drilling strategies, taking into account the location of offset hydraulic fractures, are reviewed as well.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas