Exploration and exploitation of the shale formations in the United States has continued to accelerate since the early 2000s. Once considered to exist only as a cap rock, shale is now proving to be one of the most important reservoir rocks in North America and throughout the world. The demand for production logging (PL) in these reservoirs has increased due to the desire to better understand the basis behind higher stimulation efficiency and increased production results. Data collected via production logs can be used to evaluate efforts to enhance production through better zonal targeting, modifications to completion/hydraulic fracture design, alternate zonal isolation procedures, or a combination of these measures.

Drilling extended-reach horizontal wells has allowed for more efficient exploitation of these formations but has also increased the number of potential obstacles to overcome in order to obtain complete and accurate production logs. Some of these obstacles include severe doglegs, which interfere with logging tool bending capability; substantial wellbore debris or added friction surface contact or both, impacting depth of data capture; and completion configurations that limit equipment options and ease of logging. This paper will identify these critical factors and address proper candidate well selection and job preparation. It will also illustrate a multiwell logging campaign in the Marcellus shale, which highlights the benefits of fiber-optic technology as a suitable alternative to traditional production logging techniques.