A visual demonstration of channeling
Posted by Heading Out on September 24, 2005 - 12:50pm
In the Saturday posts on oil reservoirs and why drawing down the oil too quickly can cause problems, I talked about channeling. There is a visual example of how this comes about in the failure of the repaired levee in New Orleans. When the levee was repaired they filled the hole with a combination of fine and coarse rock which was dumped at the site and raised into a wall that filled the opening and stopped the water flowing into the city. However the pressure of the water in the canal was sufficient for it to percolate through some of the passage ways that were left through the rock in that berm and so, by Thursday evening there were pictures on some news channels, from the site, of water flowing out through bottom of the wall, and this before the greater surge and failure that came later. (This is the residual permeability that was talked about in the posts back then).
At this time it was a fairly general flow through different parts of the levee, much as in drawing oil from rock, it initially comes from all parts of the rock. But as the flow continued and the smaller rock particles began to be washed out of some of the channels the flow in those areas began to open larger channels, which made it easier to move larger rocks, which caused the overlying rock pebbles to fall into the opening, and a channel all the way to the surface developed and water now began to run down that channel from the surface.
But if you look at the site now you will see that almost all the water is now (around 11 am Saturday) flowing though just two paths out into the town, and no longer percolating through the rest. The opening of those channels makes it easier for the water to divert, rather than going through the main body of the levee. Thus it is with the oil-bearing rock. If channels get developed in this way by accelerating the flow of oil out of the rock, then then oil in the volumes outside those channels does not move as readily to the well. Further if a water flood is being used to push the oil, it now has an easy passage to the well, producing a water cut to the oil being produced, that can even further lower the total volume of oil that is recovered from that reservoir.
Technorati Tags: peak oil, oil, Katrina
One of the companies I follow closely - EnCana, has had a test going on for some years now in Saskatchewan; I've been to the plant but know precious little as to how useful using CO2 to aid recovery will be, other than it has obvious appeal to countries who are trying to meet Kyoto obligations (Canada is one).
Have been meaning to float the question for a while, was reminded by this piece on the G7/G8 meeting:
(incidentally, the original G7 came together thanks to the OPEC oil crisis 30 years ago... perhaps Pres. Ford invited Canada into the group for a reason -- prior to the USSR/Russia joining the G7 officially or unofficially, Canada would have been the only country able to be a net oil exporter. Today, only Russia and Canada are.)
http://www.dose.ca/ottawa/news/story.html?s_id=QycEAjLDJ64TssMmWOFYqgHLobPAe9IdC9xb1vy4p6vn%2bXpWqzv y8Q%3d%3d
Canada Tackles Oil
WASHINGTON (Reuters) - Innovations that extend oil field lifespans by decades and extract more from oil sands are Canada's contribution to boosting world crude supply, Finance Minister Ralph Goodale said on Saturday.
Goodale told Reuters that he touched on these issues in a presentation to Group of Seven counterparts at a formal meeting on Friday and, with high oil prices plaguing economies around the world, his colleagues paid close attention.
"This positions Canada very strategically on energy supply issues," Goodale said in an interview.
Alberta is a rather perfect test case for this - you've got the considerable CO2 emissions from the oil sands projects, which are only going to get bigger and are created in a relatively small area proximity wise, so collection seems practical, it must be the 'twinning' of pipelines back to the well head which will be costly and time consuming.
The players all have oil sands projects (EnCana is an 'in-situ' oil sands extractor):
Alberta firms study ways to ship, sell CO2
you can understand this guy's position on peak oil ---him being a halliburton guy and all--- since peak oil is what caused his boss, dick cheney, to yap about peak oil in 1999, call for "a new pearl harbor" to get the oil wars going in 2000, call for 1300 to 1900 new nuke plants in may of 2001, caused cheney's National Energy Policy Development Group to emphasize hydrogen and nuclear electricity in june of 2001, ....and probably caused 9/11, which was the "new pearl harbor" cheney and his merry band of likud loons needed to kick off the wars.
okay, so i'm assuming that a MRC operation involves lots of horizontal pipe. do they drill vertical monitoring wells to give you some warning about the rising water? you dont want the whole damn line going down at the same time without warning, do you?
and if the water level is getting too high, can you back off on the water injection and hope more oil comes into the reservoir, or is it curtains once the water gets too high?
Unfortunately as we have discussed before (and I will again in a couple of Saturdays as I get more into horizontal well development) once you get much water into a horizontal well then it is done. There are a couple of remedial measures you can apply (multiphase pumping and intelligent valve control) but these are very expensive to put in, and I think that IWC has only just been tried for the first time at Shaybah as Ali mentions - though it has always been part of the plan for Haradh (which will see an increase of 300,000 bd at the beginning of next year
. I got the quote from the EIA country brief, in which it also mentions that Shaybah is now looking to increase production another 300,000 bd, which has not otherwise appeared on any published plan that I have seen, but may be the South Shaybah develpment that Ali is talking about.to give us an idea of the scale of this, there are reports that the saudis are injecting 7 million barrels of water a day into ghawar.
another report says they're injecting 500,000 barrels of sea water a day into Haradh to get 300,000 barrels per day of oil back out.
are those figures anywhere close to the truth, or does anyone know?
The gasoline yield is higher if the refinery has "cracking" units. Almost all large U.S. refineries have crackers, but this is not the case every in the world.
The typial product distribution fo a U.S. refineries is 3% LPG, 10% naphtha, 27% gasoline, 40% middle distillates (diesel, kerosene, jet-fuel), and 20% fuel oils.
Simmons's "Twilight in the Desert" never explains why this is the case -- which is strange since the whole thesis of the book is about the effect of premature water injection on reservoir life.
By the way, on a general note, the Saturday petroleum geology lessons of this web site are much appreciated.