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Using Thicker CO2 to Increase Oil Extraction Rates

By Brian Westenhaus | Thu, 18 October 2012 22:47 | 0

Oil extraction technology marches on. University of Pittsburgh engineers show crude oil extraction could be improved significantly and accessible domestic oil reserves could be expanded with their new economical CO2 thickener.

CO2 Oil Extraction
CO2 Oil Extraction Process. Image credit: Kansas Geological Society.

Most of the current U.S. oil-extraction methods involve oil being “pushed” from underground layers of porous sandstone or limestone reservoirs using a first-water-then-CO2 method known as the water-alternating-gas (WAG) method. CO2, which is obtained from natural CO2 reservoirs and pipelined to oil reservoirs, is an ideal candidate for oil extraction given its ability to push and dissolve oil from underground layers of porous rock.

But the viscosity or thickness of CO2 is too low to efficiently extract oil.  Because of the low viscosity CO2 it tends to “finger” passages through the oil rather than sweep oil forward toward the production well. This process, “viscous fingering,” results in oil production companies recovering only a small fraction of the oil that’s in a field.

During the late 1990s, a team at Pitt was the first to demonstrate that it was possible to design additives that could greatly enhance CO2′s viscosity at low concentrations, although the compounds were both costly and environmentally problematic.

Eric Beckman, George M. Bevier Professor of Engineering in Pitt’s Swanson School of Engineering and principal coinvestigator explains, “The thickeners we developed years ago were too expensive for wide use. So, in this proposal, we’re looking at designing candidates that can do the job at a reasonable cost.”

Beckman and Robert Enick, principal coinvestigator and Bayer Professor and Vice Chair for Research in Pitt’s Department of Chemical and Petroleum Engineering, intend to build upon earlier Pitt models of CO2 thickeners, but this time with a more affordable design that could cost only several dollars per pound. Ideally, their small molecule thickener would be able to increase the viscosity of pure CO2 100 times – something that hasn’t previously been accomplished.

Enid takes up the explanation with, “An affordable CO2 thickener would represent a transformational advance in enhanced oil recovery/ More than 90% of CO2 injection projects in the U.S. employ the WAG method to hinder the fingering of the CO2. However, if a thickener could be identified that could increase the viscosity of the CO2 to a value comparable to that of the oil in the underground layers of rock, then the fingering would be inhibited, the need to inject water would be eliminated, and more oil would be recovered more quickly using less CO2.”

Beckman looks forward at the market with, “It’s clear there exists a very wide market for this type of CO2 thickener. It’s been long recognized as a game-changing transformative technology because it has the potential to increase oil recovery while eliminating water injection altogether.”

The U.S. Department of Energy through the National Energy Technology Laboratory under the category of “Unconventional Gas and Oil Technologies has seen to fund the research with a $1.3 million dollar grant.

With better than 2/3rds of the discovered oil still in the crust of the earth, much of it with infrastructure in place to get it to market, all the new ideas and research to find the economical extraction methods are welcome, indeed.

By. Brian Westenhaus

Original Source: Better Oil Extraction Using CO2 With A New Additive

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