The placement of multiple hydraulic fractures along cased and cemented horizontal wellbores drilled in the direction of minimum horizontal stress is the most common completion methodology used in the development of organic shales today. Multiple perforation clusters are included in each stimulation treatment to optimize time and efficiency. This does not necessarily result in optimized productivity as many perforation clusters are frequently determined not to be contributing to production when these wellbores are evaluated with horizontal production logs.
The ability to initiate, propagate and place proppant through the near-well region of a hydraulic fracture is a function of stresses around the borehole and the orientation of the borehole relative to the principle stress field. The near-well stresses are influenced by the anisotropic geomechanical medium pervasive in organic shales. This anisotropy can dramatically alter the stress field and must be taken into account if productivity is to be optimized along a horizontal wellbore.
Field data from the Barnett Shale is evaluated to estimate the impact of this anisotropy on the ability to initiate and place hydraulic fractures through the near-well region. Fracture initiation and near-well closure pressures are measured and compared to those predicted by accounting for geomechanical anisotropy. These results are used to develop guidelines for effective perforation placement. Such techniques can be used to improve well productivity.