TITLE:
A Petrophysical Approach to Evaluation from Measured While Drilling Gamma Ray, Case Study in the Powder River and Delaware Basins
AUTHORS:
Stephanie E. Perry
KEYWORDS:
Petrophysics, Gamma Ray, Measuring While Drilling, Workflow, Delaware, Powder River
JOURNAL NAME:
Natural Science,
Vol.13 No.7,
July
30,
2021
ABSTRACT: One
of the most common subsurface data sets that is easily accessible and often
underutilized is the acquired measuring while drilling (MWD) gamma ray
(GR-GAPI) log. Data is acquired from a given gamma ray tool positioned within
the drill string and pulsed up to the surface through the mud column in the
wellbore. Typical use of the data is for subsurface geologists, drillers and
others to correlate the data to known stratigraphic signatures and steer wells
through horizontal target zones. Through that correlation, an association to
the geologic stratigraphic column can be made and the team of subsurface
scientists adjusts where, how fast, and why they choose to continue drilling.
The technique of correlation applies to both the conventional and unconventional
application. In the unconventional application,
the data is also typically acquired along the length of the horizontal
wellbore. From a petrophysical standpoint, just acquiring a gamma ray
can limit the amount of information and
ability to fully evaluate the properties along the length of the well. In this
study, we share and demonstrate how to utilize the MWD GR for
petrophysical evaluation beyond just a volume of shale or volume of clay
interpretation. The workflow will allow full integration of a comprehensive
petrophysical evaluation that can then be utilized to support all subsurface
understandings and modelling efforts.