SPWLA
Monthly Luncheon Meeting
Thursday – October 18 2018
PanAm Building- Suite 1600
601 Poydras St, New Orleans, LA 70130
11:30 – 1:00 pm
or
email Elizabeth Tanis ([email protected]) with RSVP
GEOCHEMICAL PHOTOELECTRIC (PE) LOGGING
Presented By: Jim Galford
Formation Scientific
Advisor, Haliburton
ABSTRACT
Photoelectric logs
from lithodensity tools have become a mainstay of modern logging and are
valuable to petrophysical interpretation and mineralogy identification. Like
most measurement techniques, they are not without limitations. Reliable
lithodensity photoelectric (PE) logs can only be obtained in wells drilled with
modest mud densities because the additives used to achieve high-density muds
contain high Z materials that compromise the PE measurement. In addition,
because they are often obtained with pad devices, lithodensity PE logs can be
compromised by loss of contact between the pad and the borehole wall. Mudcake
between the pad and the formation can also adversely affect lithodensity PE
measurements. A useful substitute can be obtained from neutron-induced gamma
ray spectroscopy logs when borehole conditions are not suitable for
lithodensity PE tools.
The process to obtain
PE logs from geochemical data that are compatible with lithodensity PE logs is
described. Example logs from wells drilled with low-density muds demonstrate
and validate the technique. Additional examples illustrate how geochemical PE
logs can identify lithodensity logs that have been affected by borehole
rugosity and how they be used to replace compromised or missing lithodensity PE
logs in wells drilled with heavy muds.