Abstract
The Woodford shale formation of Oklahoma is difficult to evaluate and forecast for production. Horizontal wells can often be inconsistent with offset wells, either in production rate or in expected ultimate recovery. The costs of these wells can vary greatly based on the cost and effectiveness of the fracture treatments used. Treatment can be difficult, and production rates do not always indicate open flow paths to the well.
Various logging techniques were applied in an attempt to overcome some of these treatment issues. Ideally, the imposed treatment will create a large surface area within the formation with continued, open flow paths from the contact surface in the reservoir to the wellbore. Because this is a rock mechanical problem, logs that can deliver a solution for relative rock mechanics were added to the logging program. Dipole sonic logs delivered the most consistent solution.
The paper provides a case study in which these data were applied in the Woodford formation in Oklahoma. In this study, a vertical pilot hole was drilled, dipole sonic logs were run, and rock mechanical values were calculated. The dipole sonic logs were run in casing in the horizontal wellbore. Anisotropy was calculated from these data. The fracture treatments were designed using rock mechanical information from both data sets.
This paper compares the results of the pilot well data with an offset well in which the acquired data were not used to alter treatments and initiation locations. Also, a comparison to an offset well is included, where dipole sonic in the horizontal were the only data acquired. In both cases, the better data set resulted in better completions.
