American Oil and Gas Reporter - February 2015 - 91

SpecialReport: Improved Oil Recovery
neous imbibition rate can increase as
much as 45 percent.
Figure 3 shows the oil recovery comparison at optimal salinity and formation
water salinity at 120 degrees Celsius. The
research group is looking for the most effective formulations. To help, oil companies
have provided rock cores, oil, and water
from their target oil reservoirs. With these
cores and fluids, the team is identifying
the best surfactant formulations.
Potential Field Applications
The laboratory measurements are being
scaled to determine whether the process
will produce economic volumes of oil.
Analytical calculations and computer simulations are being performed to scale the
process for particular field applications.
Even so, factors complicating the analysis
include the producing fields' relative immaturity, the Bakken's size, and the substantial extent to which reservoir character
varies in areas such as degree of fracturing,
pressure, oil saturation, permeability and
temperature. Nevertheless, results suggest
that imbibition of surfactant formulations
has substantial potential to improve oil
recovery in certain parts of the Bakken.
In one scenario, the surfactant-water
formulation could be injected through a
horizontal injection well at the bottom of
the reservoir, and similarly, a horizontal
production well at the top of the reservoir
could collect oil and other fluids. Injection
and production rates would be adjusted
to maximize the oil cut. Of course, optimum timing, volumes and rates associated
with this process depend on fracture in-

tensity, local permeability, well spacing,
and the rock's inherent imbibition rates.
Future simulation efforts will examine
these parameters and attempt to identify
viable conditions for a field application.
Alternately, the process could be adapted
using the "huff and puff" method in individual wells and in situations where fracture
complexity is favorable. As with the aforementioned flooding application, the
process's optimum timing, volume and
rate also will depend on fracture intensity,
the rock's inherent imbibition, and formation pressure. Future analysis of the process
will include an effort to identify viable
conditions for a field application.
Meanwhile, UND's research efforts
have caught the interest of oil companies
active in the Bakken play. One oil company
is close to implementing the process in
the field. In addition to funding from
RPSEA, the UND group has received
backing from a number of oil companies-Statoil, ConocoPhillips, Noble Energy-to develop the process for their operations not only in the Bakken, but other
shale formations, including the Niobrara.
Meanwhile, Hess Corporation's participation in the RPSEA-funded project has
included providing oil and core samples.
Chemical companies TIORCO, NALCO Champion's CorsiTech, and Flotek
Industries' CESI Chemical have provided
surfactants to be tested as part of the new
process. The North Dakota Geological
Survey's Wilson M. Laird Core & Sample
Library on the UND campus also have
provided core samples.
In summary, UND's innovative research

is developing an exciting new process
that may keep the Bakken's oil production
high, even at low oil prices.
Ì

DONGMEI
WANG

Dongmei Wang is a petroleum engineering scientist and adjunct professor
in the Harold Hamm School of Geology
& Geological Engineering at the University of North Dakota in Grand Forks.
Her expertise is in enhanced oil recovery
project planning, numerical reservoir
simulation, and economic evaluation.
Wang previously served as a department
chief and senior engineer of the enhanced oil recovery department, and
director of the Overseas Petroleum Potential Evaluation Center at the Exploration and Development Research
Institute of Daqing Oilfield Company
of PetroChina. She holds bachelors' in
computer software from the Daqing
Petroleum Institute of China and in
computer science from the University
of Changchun Science & Technology
of China, and an M.S. and Ph.D. from
the Research Institute of Petroleum Exploration & Development.

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FEBRUARY 2015 91

American Oil and Gas Reporter - February 2015

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