Tulsa SPWLA
Monthly Luncheon Meeting
Thursday Nov 14 2019
Tulsa University
Helmerich Hall- Room 121
800 S Tucker Dr.
Tulsa, OK 74104
11:30 – 1:30 pm
Register and pay online or pay cash/check at the door.
RSVP: [email protected]
Cost - $25 for Professionals and FREE to students with student ID
Thermal maturity-adjusted log interpretation (TMALI) in organic shales
Authors: Paul Craddock, Rick Lewis, Jeff Miles, and Drew
Pomerantz (Schlumberger)
Presented By: Paul Craddock - Schlumberger, North America
ABSTRACT:
The petrophysical interpretation
of downhole logs requires knowledge of accurate matrix
properties. In organic-rich mudrocks (shale), the presence of
abundant kerogen (solid, insoluble organic matter) has a particularly large and
variable impact on matrix properties. Matrix properties are highly
sensitive to kerogen properties because kerogen is compositionally distinct
from minerals that comprise the remainder of the matrix. In practice,
kerogen properties must be accurately known to separate tool responses to kerogen
(in the matrix volume) and fluids (in the pore volume), to arrive at accurate
volumetric interpretations. Unfortunately, relevant petrophysical
properties of kerogen are nearly always unknown in the formation of interest,
and otherwise impractical or impossible to measure.
In this talk, I will present
the petrophysical properties of kerogen from the study of more than 50 global
shale samples. The determined kerogen properties include measured
chemical composition and absolute density, as well as calculated nuclear
properties such as apparent log density, hydrogen index, thermal and epithermal
neutron porosities, photoelectric factor, macroscopic capture cross-section
(Sigma), and fast neutron cross-section. For kerogen samples relevant to
the petroleum industry (predominantly type II with thermal maturity ranging
from immature to dry gas), it is found that petrophysical properties are
controlled mainly by thermal maturity, with differences between
basins/formations having relatively little effect on kerogen properties.
As a result, universal curves can be established that relate kerogen
properties to thermal maturity. This thermal maturity-adjusted log
interpretation (TMALI) establishes a consistent framework to evaluate organic
shales globally, requiring only knowledge of the thermal maturity of the play
of interest, and provides more accurate, robust, and confident estimates of
critical formation parameters including porosity, saturation, and
hydrocarbon-in-place.
BIO: Paul Craddock is a geochemist
and Senior Research Scientist in the Applied Math & Data Analytics
Department at Schlumberger-Doll Research Center in Cambridge, Massachusetts.
His research provides solutions for reservoir characterization using nuclear,
X-ray, and infrared spectroscopy methods, such as to derive saturation in
low-resistivity pay in conventional reservoirs using nuclear spectroscopy;
identify favorable pay for well placement and production in unconventional resources
(“RPI”); integrate cuttings and logs for enhanced petrophysics in shale
(“DRIFTS”); and optimize kerogen endpoints for global shale interpretations
(“TMALI”). Paul received a PhD in chemical oceanography from Massachusetts
Institute of Technology/Woods Hole Oceanographic Institution in 2009 and has
co-authored more than 40 technical journal and conference publications. Paul is
twice a SPWLA Distinguished Speaker and his paper “Thermal maturity-adjusted
log interpretation (TMALI) in organic shales” was awarded Best Oral
Presentation at the 2019 SPWLA 60th Annual Logging Symposium.