Perforation Location Selection and Zonal Contribution Study of the Wolfberry Play in the Midland Basin

Abstract

The selection of perforation zones in unconventional reservoirs can be very challenging. Great strides have been made by the integration of both engineering and geological data. However, a successful perforation zone selection methodology in one Basin might not be successful in another. This paper presents a pilot study on a perforation zone selection and zonal contribution in a vertical well in the Midland Basin. Reservoir characteristics as well as the geomechanical properties of a formation are important in the selection of optimum locations for limited entry perforations. In this work, several data sets, including openhole logs, radioactive tracer logs, amount of proppant pumped, PVT sampling, and 3D fracture modeling were integrated. Additionally, temperature logs were used to identify zonal contributions during the early flowing period. Results from this work indicate that closure stress is the dominant parameter greatly affecting the fracture initiation and growth in the observed well while both high and low brittleness sections were observed similar behavioris of hydraulic fracture failure. Learnings from radioactive proppant tracers and 3D fracture modeling efforts helped to identify the importance of closure stress in addition to brittleness in perforation placement identification. Temperature log interpretations were correlated with proppant tracers and fracture modeling which qualitatively indicates that the Lower Spraberry and Wolfcamp B formations are big contributors to production and thus good potentials targets for horizontal wells.