American Oil and Gas Reporter - PBIOS 2014 Official Program Guide - 173

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UTPB Leads Permian Basin ROZ Study
By Robert C. Trentham
ODESSA, TX.-The University of
Texas of the Permian Basin (UTPB) is
situated in the heart of the Permian Basin
in Odessa, and is working closely with
the oil and gas industry to research areas
of critical importance to the continued
growth of the industry in the basin and
elsewhere.
Specifically, UTPB's Center for Energy
and Economic Diversification (CEED),
and its geology and petroleum engineering
departments are working on modeling,
case studies, and the regional importance
of residual oil zones (ROZs) and the
long-term potential for carbon dioxide
enhanced oil recovery in a portion of the
upper Permian carbonate reservoirs that,
until recently, has not been considered to
be productive.
ROZs exist both below existing oil
fields (the ROZs there are referred to as
brownfields) and in areas where there is
no commercial production (referred to
as greenfields). It is estimated that more
than 100 billion barrels of oil may be
trapped in these brownfield and greenfield
ROZs, and that with CO2 EOR, onethird, or approximately 30 billion barrels,
could be recovered economically.
Currently, there are 15 ROZ CO2 EOR
projects in the Permian Basin, with daily
production of about 15,000 barrels of
oil. Although many of these projects are
relatively new, some have been in production for more than a decade.
ROZ Formation
There are virtually no publically available studies of how the ROZs came into
being, case studies of the potential for
small operators to manage ROZ floods,
nor recent estimates of the potential for
ROZ CO2 reserves in the Permian Basin
or elsewhere.
UTPB is working with a number of
industry partners-Melzer Consulting, Arcadis-US Inc., Advanced Resources International (ARI), Chevron Corporation,
Legado Resources, and Kinder Morgan-
and local consultants Phil Eager and
Steve Robichaud on three projects sponsored by the Department of Energy through

the Research Partnership to Secure Energy
for America to provide answers to many
of the fundamental questions concerning
ROZs. Melzer Consulting and UTPB
acted as co-principal investigators on all
three projects.
The first study centered on modeling
how ROZs formed. An understanding of
the post-oil emplacement history of the
basin was developed utilizing these well
data:
* Location information;
* Well tops;
* Correlations (cross sections);
* Pressure data (drill stem test);
* Well test data;
* Permeability, porosity, and saturation
data (core); and
* Water chemistry data from the petroleum industry and the U.S. Geological
Survey.
UTPB students gained knowledge of
the petroleum industry as they helped
gather the well data for input into the
model. Arcadis-US, using software commonly used in groundwater modeling,
developed a model of "Mother Nature's

waterflood," as the ROZ is commonly
referred to.
UTPB geology faculty developed a
post-oil emplacement time frame for
uplifts during the Laramide (end of Cretaceous), and Basin and Range (Oligocene
through Middle Miocene, 15 million-30
million years ago) periods, which are the
driving force for meteoric-derived fluids
to flush oil out of the ROZs. This time
frame, along with the well data, was reviewed by the industry partners.
The modeled area is 250 miles long
and 50 miles wide, and extends across
from Carlsbad, N.M., to Hobbs, N.M.,
and then south past Imperial, Tx. It was
determined from the model that the
number of pore volume flushes ranged
from 20 to 50 over a 15-million year
(Late Oligocene through Middle Miocene)
time frame, with fluids moving at less
than one foot a year. This is well within
the range we anticipated.
We also were able to calculate that,
based on the amount of native sulfur
present in a decommissioned "sulfur
mine" area in northern Pecos County,

Courses preparing students for oil and gas industry careers as well as post-graduate
research at the University of Texas of the Permian Basin range from chemistry and geology to industrial technology and petroleum engineering. Research and educational
programs are designed to advance the industry's progress in carbon dioxide enhanced
oil recovery, including realizing the immense potential of CO2 injection in residual oil
zones below both existing oil fields and areas where no commercial production has ever
been established.

OCTOBER PBIOS 2014 173

American Oil and Gas Reporter - PBIOS 2014 Official Program Guide

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