|Novel Self-Thickening Chemicals for Improved Conformance Control
||Last Reviewed 10/31/2011
The goal of this project is to develop a cost-effective, improved chemical technology to increase oil production from mature fields in the United States. This technology also has the environmental benefit of decreasing the volume of water co-produced with the oil.
ChemEOR, Covina, CA 91723
Most oil reservoirs accessed by small producers are mature fields with low oil production and high (typically over 90%) water cut due to extensive water flooding. Higher levels of water production result in increased levels of corrosion and scale, water-oil separation costs, and environmental impacts. Eventually this situation will lead to uneconomic conditions and well shut-in. Consequently, producing zones are often abandoned in an attempt to avoid water contact, even when the intervals still retain large volumes of recoverable hydrocarbons.
Reservoir heterogeneity severely impacts the flow of gas, oil, and water in the reservoir and leads to premature water production and low recovery of the original oil-in place. To maintain reservoir pressure and produce additional oil, these reservoirs have usually been developed by water flooding from the early stage of their development. Reservoir heterogeneity can be caused by variations in reservoir porosity and permeability, fracturing (natural and induced), and/or channeling due to mineral dissolution during water flooding. Reservoir heterogeneity is further complicated by the common practice of completing wells into multiple pay zones, thus increasing total reservoir thickness and exposing the wellbore to a variety of reservoir rock characteristics. Polymer and gel treatments are important options to correct reservoir heterogeneity.
ChemEOR, Inc. is developing a new chemical technology to increase the rate of oil production and recovery from mature U.S. oil fields. This technology is based on unique, single-component chemical products that when added to brines will self-thicken over time inside the reservoir. Such low-cost chemical solution treatments will selectively block flow in previously watered-out channels of the oil reservoir. Under certain brine and temperature conditions, these solutions will exhibit an increase in viscosity (to a gel state in some cases) over time. The normal injection water that follows such a treatment will be diverted into oil-rich, previously un-swept areas of the reservoir and recover additional oil. This same concept may be applied in production wells to reduce water production.
This project will increase hydrocarbon recovery and reduce environmental impacts (via decreasing produced water volumes).
Tapping into additional oil and gas supplies within the nation's most mature wells can be an important contributor to U.S. energy security. The Department of Energy has estimated the enhanced oil recovery (EOR) target for the U.S. to be about 377 billion barrels (bbl) of oil. Simple technologies like self-thickening chemical injection are well suited to address the vast reserves of light oil left in mature, waterflooded fields. If this process could recover just 1% of this oil bypassed by waterflooding, this would represent 3.7 billion bbl more domestic reserves.
Wells become unprofitable to operate due to excess water production accompanied by low oil production. A reduction in produced water and associated costs will lower the number of abandoned wells and lead to production of a larger percentage of the original oil-in-place.
The general theme of lower volumes of water associated with hydrocarbon production is a key goal of several U.S. agencies, including DOE. Produced water by itself raises environmental concerns due to its often substantial dissolved salt concentration.
The chemistry of the self-thickening agents will make it possible to match a self-thickening product with available produced water. It will be possible to use produced water as supplemental make-up water in stimulations instead of using a valuable fresh water resource. This strategy may make it possible to consume and further recycle some portion of the produced water instead of disposing it.
Tests performed in Berea sandstone containing medium gravity crude oil compared the oil recovery efficiency for a candidate T85 product versus an ordinary polyacrylamide. The test with the T85 recovered 70% of the tertiary oil, while the test with polyacrylamide polymer recovered only 25%.
Synthetic co-polymers with two or more chemical groups successfully passed initial screening.
Current Status (October 2011)
The project has been completed.
Project Start: June 19, 2010
Project End: March 18, 2011
DOE Contribution: $97,500
Performer Contribution: $0
NETL – Sinisha (Jay) Jikich (Sinisha.Jikich@netl.doe.gov or 304-285-4320)
ChemEOR – Patrick Shuler (firstname.lastname@example.org or 909-632-8639)