Oil & Natural Gas Projects
Exploration and Production Technologies
Conformance Improvement Using Gels
This project was selected in response to DOE's Oil Exploration and Production
solicitation DE-PS26-01NT41048, focus area Reservoir Efficiency Processes.
This project had two objectives: 1) to identify gel compositions and conditions
that substantially reduce flow through fractures that allow direct channeling
between wells, and 2) to optimize treatments in fractured production wells,
where the gel must reduce permeability to water much more than that to oil.
New Mexico Petroleum Recovery Research Center
New Mexico Institute of Mining and Technology
This project 1) identified the mechanism for why some gels can reduce permeability
to water more than to oil, 2) established the mechanism for propagation of formed
gels in fractures and proposed a more credible mechanism for filter-cake formation
in fractures, and 3) established a web site that allows anyone to view the state
of the art in water-shutoff technology using gels.
Understanding the mechanisms by which gels reduce water and oil production helps
increase the reliability of gel treatments during water-shutoff efforts in field
applications. Researchers developed a web site that details many different types
of water shutoff problems and provides a water shutoff strategy with relevant
field examples and important information about the properties of polymers, gelants,
and gels-what they can and cannot do, where and how gel treatments should (and
should not) be placed, and how to assess the effectiveness of the gel treatment.
This site can be accessed at http://baervan.nmt.edu/randy/. A search engine
is included that covers all the project's reports and publications, including
annual reports from 1990 forward.
Bettering the performance of gels in shutting off water production in improved
oil recovery (IOR) operations boosts oil production and ultimate reserves recovery
while benefiting the environment through mitigating the handling and disposal
of large volumes of produced water.
Fractures (either natural or artificially induced) often cause excess water
production and reduced oil recovery efficiency, especially during waterfloods
and other IOR projects; they also constitute a channeling and water-production
problem that has a high potential for successful treatment by gels and certain
other chemical blocking agents. Especially in fractured production wells, gels
can substantially diminish water production if the gel can reduce permeability
to water much more than to oil. Studies were needed to 1) determine the correct
mechanism(s) for the disproportionate permeability reduction, 2) identify conditions
that maximize the phenomenon, 3) find materials and methods that make the phenomenon
predictable and controllable, and 4) establish a methodology to determine how
much gelant should be injected in a given fractured production well.
X-ray computed microtomography (XMT) was used to understand why gels reduce
permeability to water more than that to oil. That work revealed that "strong"
Cr(III)-acetate-HPAM gels formed in virtually all aqueous pore spaces. For normal
pressure gradients, water injected after gel placement was forced to flow through
the gel itself, experiencing microdarcy permeabilities. In contrast, even for
relatively low-pressure gradients, oil injection destroyed gel or reduced the
gel volume so as to enhance oil permeability (relative to water flow). During
subsequent water flow (after oil flow and after gel placement), the gel trapped
much higher levels of residual oil (relative to the Sor before gel placement)-thus
again providing a permeability to water that was much less than that to oil.
This three-year project was completed September 30, 2004.
Seright, R.S., Conformance Improvement Using Gels, Annual Technical Progress
Reports, U.S. DOE Report DOE/BC/15316-2, 4, and 6, September 2002, September
2003, and September 2004.
Sydansk, R.D., Al-Dhafeeri, A.M., Xiong, Y., and Seright, R.S., Polymer Gels
Formulated with a Combination of High- and Low-Molecular-Weight Polymers Provide
Improve Performances for Water-Shutoff Treatments of Fractured Production Wells,
SPE Production & Facilities, November 2004, 19(4), 229-236.
Seright, R.S., Lane, R.H., and Sydansk, R.D., A Strategy for Attacking Excess
Water Production, SPE Production and Facilities, August 2003, 158-169.
Seright, R.S., An Alternative View of Filter-Cake Formation in Fractures Inspired
by Cr(III)-Acetate-HPAM Gel Extrusion, SPE Production and Facilities, February
Seright, R.S, Liang J., Lindquist, B.W., and Dunsmuir, J.H., Characterizing
Disproportionate Permeability Reduction Using Synchrotron X-Ray Computed Microtomography,
SPE Reservoir Evaluation & Engineering, 5(5), October 2002, 355-364.
Project Start: September 9, 2001
Project End: November 11, 2004
Anticipated DOE Contribution: $1,226,875
Performer Contribution: $612,518 (33.3% of total)
NETL - Jerry Casteel (firstname.lastname@example.org or 918-699-2042)
PRRC - Randy Seright (email@example.com or 505-835-5571)
Demonstrating why gels reduce permeability to water more than to oil.