The Oil Drum: Canada

199 comments on Extracting Heavy Oil: Using Toe to Heel Air Injection (THAI)

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1observer on August 28, 2007 - 3:28pm

1observer, do you have any idea if there are depth limitations to the process, in other word, the general range
in which this should be considered. Also, your story suggests that this can be used in sands with a gas cap and water in the sands. Is there a range on the water content?

Bob, I don't know anything about salt domes but perhaps the following will help you. I would like to point out that the current operating wells are 500 meters and have an expected life of over 5 years.

Q : Are there any reservoir characteristics that are crucial for success?

A : As in other vertical drainage processes, vertical permeability is important. Because much of the drainage process in THAI™ operates in the gas phase, we anticipate that THAI™ will be less impacted by reduced vertical permeability than SAGD. Otherwise the technology is very flexible, and in contrast to SAGD, can be applied to deep heavy oil reservoirs, thinner sands and to lighter oils.
Q : Can THAI™ be used in non oil sands reservoirs?

A : Conventional in-situ combustion has been tried in medium gravity reservoirs with some success to increase overall recovery factors. We anticipate that the added control and elevated withdrawal rates achievable with the use of horizontal wells could prove to be very beneficial. Successful physical model runs have been achieved on oils as light as 30° API and also on steam-flooded sands with permeability over 1-Darcy.
Q : Are there depth limitations to the process?

A : In steam injection projects like SAGD, condensation of the steam under high pressure and wellbore heat losses significantly impact the economic viability of the project for all but shallow reservoirs. Because the heat is created in-situ with THAI™, the process can be applied to much deeper reservoirs. Of course, temperature rises with depth and therefore many deep heavy oil reservoirs already benefit from significant in–situ viscosity reduction, but we anticipate that THAI™ could still be used effectively in these reservoirs to raise overall recovery levels and provide the other THAI™ benefits.

Q : What are the typical reservoir parameters used to model the THAI™ process?

A : The typical THAI™ reservoir parameters are:

Oil Saturation = 80% Assumed but the process could be used at saturation levels as low as 50%
Oil Quality = 8° API or greater
Oil Viscosity At Reservoir Temp. = <250,000 cP
Vertical Permeability = 0.5 D
Net Pay = >10m
Shale Content = No continuous lenses, but shale breaks are not expected to be problematic
Clay Content = clay is beneficial to catalyze cracking upgrading reactions.
Thief Zones = not expected to be problematic

http://www.petrobank.com/hea-faq.html

Frankly, I'm not sure this is economic without a lot of work at cutting costs. Its risky, and a long way from roads and pipelines for not a great return. Maybe I'm way off base in my cost guesstimate, or the potential returns. But 4,716,000 barrels looks like an awfull lot of grease to get out of a ten acre patch of land. Considering the price risk of a general recession, this looks pretty marginal for unproved technology.

If you're referring to salt domes that may be so but if you're referring to oil sands I respectfully suggest that you re-do the numbers. Thanks for your interest Bob.

Don

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oilmanbob on August 29, 2007 - 1:06am

Don

A 5.2 year life makes a real difference, and thanks for the info, also a 500 meter reach. I'll be happy to redo and get back with you. There's a lot of stranded oil in Texas, production was basicially uncontrolled before 1936, and the East Texas field was discovered in 1930, the peak of discovery. It was drilled to a well density of 1 well per 6 acres.

The reservoir energy was dissipated. They flared or vented the natural gas, and the absolute open flow caused massive coning. The US Department of Energy Fossil Fuels Department thinks that the average recovery rate on the old fields was around 10% of the original oil in place, and the University of Texas Bureau of Economic Geology says 10% to 20).

The current prospect I'm working up uses a figure of 20% O.O.I.P., but thats pretty arbitrary, but it still yeilds a figure of 100 million barrels OOIP, a hefty target. Its 18 gravity sweet, and an oil pipeline is less than 1/4 mile away, the refineries located about 60 miles as the crow flies. Salt domes have numerous reservoirs, and the one I'm planning to reenter first is apparently about 50 acres, and old reef, so I doubt its suitable. I'd guess at your temperatures of 700o farenheight the lime would cook to cement. But there's plenty more reservoirs, mostly frio and miocene sands, and they might be very suitable they're high silica. I'm trying to raise $500 K to buy up the rest of the formerly productive acreage, about 2,000 acres and I've been shamelessly chumming for investors here because I've only got about $30K of my own to put in on the deal. And I have at least 12 more similar prospects within 200 miles, mostly too big for me to handle, so i'm focusing on one that i think I can put together on my own.

Salt domes and structures control about 90% of the oil production in the Gulf Coast and Louisiana, plus the Gulf of Mexico and the Golden Lane of Mexico. Bob Ebersole