More Oil Soon

September 10, 2008 | 4 Comments

The Norwegians have studied using seawater as an enhanced oil recovery process in chalk like formations. More than 50% of the world’s oil reservoirs are in these carbonate rocks. Crude oil likes to hang in there as the oil “wets” to the surfaces so making it strongly absorbed. Water injection has been used as a cheap enhanced oil recovery, but the fresh water flows through fractures leaving much of the oil and rock unaffected and doesn’t impact the connection between the oil and the rock.

All this chalk rock is from the skeletons of plankton algae called coccolithophorids. Over time the calcium, oil and water trapped together. The rock is a calcium carbonate with the organic characteristics that allow reactions with the chemicals of contemporary seawater. Ca2+, Mg2+, and SO42− of seawater have been identified as chemicals that can crack open the thermodynamic equilibrium. The equilibrium is seen as the “wettability” problem. When the seawater enters the structure the chemicals break the bond between the oil and rock allowing the water to displace the oil.

That makes the temperature important, as energy is required for the organic chemical reactions to occur. Compared to sandstones, which are inorganic rock structures, the importance of heat energy determines the activity of the incoming seawater. Too cool and it won’t go, or rather it won’t go fast enough to make any difference.

Seawater Wettability Model

Seawater Wettability Model

Recently the University of Stavenger showed that seawater with the potential determining ions of the minerals properly concentrated could promote the reservoir to a more “water wet” rather than “oil wet” condition. The tests at the Ekofisk field increased the imbibition (uptake of the water into the small pores). What was also learned was the higher temperatures experienced more effectiveness. The Norwegians also learned that when doing a viscous reservoir flooding that a very small differential of 1 psi increased the recovery from 40% to 60%.

When we think of oil reservoir rock what is in mind is a rock sponge with tiny pores filled with oil. As the oil moves to the well the pressure is reduced. Rock compresses poorly so very little is gained after the pressure from gas above or water below is taken off by production. Those little pores have been an issue for decades. The realization that the organic chemistry aspects of the calcium rock and the available chemical reactivity of seawater is now a documented and understood.

What this should mean is that there will be continued production from oil fields thought to be past economic productivity. The researchers are looking onto the application of seawater into limestone formations, which are also organic formed rock. It may well be possible to greatly enhance these reservoirs too.

When one looks over the study paper one point shines through. The new seawater process accomplishes a strong cleaning action on the oil reservoir that drives much more oil free to be pumped for use. The other striking fact is that this depth of experimentation is successful and it’s really in the early stages.

There is an old saying that applies here, “There is a lot more oil where that came from!” Sometime I wonder when it’s said that 1/3rd of the oil is pumped out, that it might prove to be an overstated estimate someday.


4 Comments so far

  1. small business grants on November 8, 2010 10:31 AM

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  2. Charlie Pollack on May 21, 2011 10:31 PM

    Thanks for posting. Good to see that not everyone is using RSS feeds to build their blogs 😉

  3. Adelle Duggin on September 1, 2011 4:57 PM

    This post makes a lot of sense !

  4. Jayson Breitling on October 11, 2011 2:32 PM

    Good! Thank you! I always wanted to write in my site something like that. Can I take part of your post to my blog?

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