Oil & Natural Gas Projects
Exploration and Production Technologies
Investigation of Phase & Emulsion Behavior, Surfactant Retention, Condensate/Water/Ethanol
This project was selected under DOE's Historically Black Colleges and Universities
The project goal was to characterize the phase and emulsion behavior, surfactant
retention, and condensate recovery for cosurfactants such as ethanol, crucial
factors for increasing recovery of condensate in gas-condensate fields. Phase
work would obtain optimal salinity and temperature in which all three phases
coexist. These tests were to be performed with a condensate and with a comparable
refined hydrocarbon, for varying concentrations of brine and cosurfactant (ethanol)
and for a wide range of temperatures within the reported bound seen in gas-condensate
Phase work was completed, including salinity and temperature scans and coreflooding
experiments. An experimental system for electrical conductivity measurements
was set up, tested, and calibrated. Conductivity measurements for conjugate
pair phases were completed by April 2005.
Achieving increased production in partially depleted gas and gas condensate
fields is essential for many gas producing companies. Incremental production
in mature fields can be very profitable, especially in developed countries.
Worldwide, the potential for production and improved recovery from gas-condensate
fields is considerable.
The major factors causing hydrocarbon losses in a reservoir during production
of gas and gas-condensate fields are related to pressure depletion, retrograde
condensation, and water encroachment. The most widespread and simple method
of producing gas and gas-condensate fields is by depletion, utilizing only the
natural reservoir pressure. The major disadvantage of this method is low condensate
The ultimate condensate recovery from gas-condensate fields is 30-60%, depending
upon the initial content of condensate in the gas. By comparison, the final
recovery of gas in dry gas fields can be up to 95%. Despite the low recovery
of condensate associated with natural depletion, this method is still widely
used in the majority of the world's gas-condensate fields. The reasons for this
are both technological and economic. In order to improve recovery of condensate
from gas-condensate fields, innovative methods are required, as is a greater
understanding of fluid behavior in such reservoirs for secondary recovery efforts.
Project tasks called for researchers to perform:
- Salinity scans with a condensate to obtain optimal salinity.
- Temperature experiments for various concentrations of the cosurfactant.
- Emulsion morphology experiments to obtain electrical conductivity vs. phase
volume fraction data for top/bottom, top/middle, and middle/bottom phases that
form the sides of a tie triangle diagram.
Detailed measurements and analyses were performed on ethylbenzene and condensate
for a broad range of salinity and temperatures, inversion hysteresis of the
emulsions was determined, and the cosurfactant was subjected to corefloodings
to obtain surfactant retention and condensate recovery efficiency information.
Salinity and temperature scans, emulsion inversion measurements and analyses
were performed at Morehouse College. Coreflooding measurements and analyses
were performed at Surtek, Inc., Golden, CO.
All measurements were made using ethanol as the cosurfactant. Surtek provided
the condensate obtained from a U.S. gas-condensate field. Ethylbenzene was
chosen as the refined hydrocarbon to be tested because it has the equivalent
carbon number of the condensate. The phase behavior of ethylbenzene resembled
that of ethane. Ethylbenzene simplified the experiments and reduced their
cost by allowing the testing to proceed at atmospheric pressure instead of
the high pressure required by ethane.
Current Status (August 2005)
Measured conductivity data were compared with the predictions and completed
by the end of summer 2005.
Presentations were made at the spring 2004 seminar series of the Department
of Physics and Dual Degree Engineering, Morehouse College, Atlanta, GA, and
at the DOE/SPE IOR conference in Tulsa, OK, in April 2004.
Project Start: October 1, 2002
Project End: September 30, 2005
Anticipated DOE Contribution: $184,684
Performer Contribution: $0
NETL - Jesse Garcia (firstname.lastname@example.org or 918-699-2036)
Clark Atlanta University - Ramanathan Sampath (email@example.com or 404-880-6733)