TITLE:
Petrophysical Tutorial, Lessons Learned, and Evaluation Workflow: A Case Study in the Power River Basin
AUTHORS:
Stephanie E. Perry, Matthew White
KEYWORDS:
Petrophysics, Wireline, Workflow, Niobrara, Power River
JOURNAL NAME:
Natural Science,
Vol.13 No.5,
May
31,
2021
ABSTRACT: The
objective is to empower the reader and scientific community with the knowledge
and specific applicable equations to then reproduce the critical rock and fluid
attributes in the Powder River Basin. To then continue to unravel the basin and
its potential (both conventionally and unconventionally). The overall goal is
to ensure the transfer of knowledge and communication
of a petrophysical workflow that can then also influence application to other
basins worldwide. The Powder River Basin is
in southeast Montana and northeast Wyoming and is a prolific oil and gas
(hydrocarbon-prone) sedimentary basin related to the greater Rockies chain/series of hydrocarbon-bearing
basins (ex. Big Horn, Greater Green River, Denver-Jules). In this study, we briefly set-up the geological
background of the Powder River Basin and the importance/ relevance to then
tackling subsurface petrophysical evaluation on a regional scale. Approximately,
200 wells were evaluated petrophysically by a combined deterministic and
inversion-based workflow representing an effort to share best practices, approaches, and the relative trends to apply in the
basin to unravel the stratigraphic hydrocarbon potential in place. An extensive
workflow involving basic petrophysical approaches such as raw log applicable
cutoffs and volume of clay determination are shared as well as extending knowledge and application into advanced
petrophysics through geochemical property derivation and impact of those
derived properties as well as bound versus free water and hydrocarbon understanding. Results of the petrophysical
analysis highlight the varying properties in conventional and unconventional
formations (example Niobrara). The results of how and why the petrophysical
approach was calibrated and then applied are the primary efforts accomplished.