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Deep water oil

General discussions of the systemic, societal and civilisational effects of depletion.

Re: Prospects for Deep Water Oil

Unread postby obixman » Thu 10 Jul 2008, 16:51:27

Two things about deep water....

1) In order for there to be Oil, first there needs to be (or have been) a fairly thick layer(s) of sediment. With the exception of a few places, deep water simply doesn't have thick enough sediments to be a major oil source.

2) Also for the most part, oil containing sediments have to be old (or the oil has to to come from old sediments) - and for the most part deep water sediments are new .. and not really connected via a migration path to older sediments. Again, as in point one, there are some exceptions, but they are VERY few.

You are right in that below a certain depth (about 20,000 feet [7,000 meters]) the sediment has for the most part had the oil cooked out into gas. There are few oil resevoirs below that depth (which does change somewhat depending on the history and geothermal history of the basin you look at.)

I was with Gulf Oil in the mid 70's when it became obvious that there was a depth below which Oil will not be found, the revision in thinking was great, and a fair number of people in the industry became quietly aware that peak oil was going to come about much quicker than they thought....
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Re: Prospects for Deep Water Oil

Unread postby ltplayer » Thu 10 Jul 2008, 16:51:59

The book was called "Hubbert's Peak".
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Re: Prospects for Deep Water Oil

Unread postby entropyfails » Tue 15 Jul 2008, 02:26:45

Read

http://en.wikipedia.org/wiki/Cracking_(chemistry)

and
http://en.wikipedia.org/wiki/Geothermal_gradient

and probably
http://www.theoildrum.com/tag/deepwater


You were not mislead. The earth gets warmer the deeper you go. Oil breaks down at those temperatures. There are only a few special spots in the world where deepwater wells work, we may find more, but they are likely to be very small reserves.
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Re: Prospects for Deep Water Oil

Unread postby ROCKMAN » Wed 16 Jul 2008, 10:25:20

Everyone is right and wrong. To be exact it's not so much a depth limitation but a temperature limit. Yep..temp breaks oil down. A lot of the natural gas resource plays you've been reading about have followed that very history: big oil accumulations turned into big NG accumulations. And yes, there aren't too many spots where you can drill to far without hitting the thermal barrier. The Gulf of Mexico is one spot. Last fall I drilled the 3rd deepest well in the western hemisphere (34,000'). A $148 million dry hole. Not too hot for oil to survive though. There just wasn't an accumulation in that spot.

Other deep but cool enough spots are off the w coast of Africa, off the w coast of the US, off Alaska. The big DW play everyone talks about now is offshore Brazil. Though the water depths are significant (3000'+) the formations are actually relatively shallow (above 15,000')
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Re: Prospects for Deep Water Oil

Unread postby dorlomin » Wed 16 Jul 2008, 12:32:19

Would I be wrong in thinking that the abysall plain would tend to be lacking in cap rock type formations to trap any oil? Also the Atlantic would mostly be too young for the Mid-Cretatious and Upper-Jurassic times when most of the oil formed. would it not?

Another question the oceanic crust is much thinner than the continents would this mean that the thermal gradient is much thinner so is the so called 'oil window' inherently thinner on the ocean floor\ abysal plain?
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Re: Prospects for Deep Water Oil

Unread postby rockdoc123 » Thu 17 Jul 2008, 09:29:40

ROCKMAN temperature is most important but time also comes into the equation. Long periods at lower temperatures is as effective converting source to oil as higher temps over shorter periods. The Arrehenius function determines the response. That being said a lot of the major oil and gas discovered in deep to ultra deep water is in Tertiary sediments which means that temperature does take a greater role. However when we look at potential Cretaceous or older reservoirs in places like West Africa time and an understanding of burial and uplift history is pretty crucial. If you are speaking of phase change...(i.e liquid oil to condensate or gas) then temperature is of course the main player with time being somewhat inconsequential.
And that segways to Dorlomin's question. Yes the oceanic crust is thinner and because of the rock type is also a better thermal conductor. Rule of thumb used to be that for cratonic areas (continental crust) the geothermal gradient is somewhere in the order of 10 - 20 C/km, which moves to about 40 C/km for transitional crust and up in the 60 and higher range (depending on how old it is) for oceanic crust (the highest heat flow would be at modern rifts where it is well over 100 C/km an example being the east africa rift system). The interesting part of this is that for Tertiary deltaic or turbidite fan deposits the thickest deposition is at some point from shoreline which might be shallow to deep water. In cases such as offshore Namibia and the Nile Delta the thickness of sediments is so great that the older source rocks generate gas. As you move into deeper and deeper water the reservoir section thins depositionally which in turn results in the source rock at some point being in the oil kitchen. Offshore South Africa that is demonstrated by the Ocean Drilling Program wells which intersected Cretaceous source rocks which are immature out board of a major gas field that has the source rocks in the gas window. So somewhere there should be an oil rim to major gas plays like the Nile Delta. Shell paid a huge amount of money looking for it many years ago with no success. It's a complex modeling problem that the industry has struggled with for a long time.
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Re: Prospects for Deep Water Oil

Unread postby ROCKMAN » Thu 17 Jul 2008, 13:39:19

So true rockdoc,

I'm working E Tx and the basin centered gas plays there have had 60 million years to cook.
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Re: Prospects for Deep Water Oil

Unread postby ROCKMAN » Thu 17 Jul 2008, 13:46:13

dorlomin,

There's a lot of younger oil then you might think. Rockdoc talks about it in detail. As far as the Atlantic goes are you refering to the lack of potential in the center of the basin? If not, check out the near shore discoveries off the Canadian Atlantic coast. Not nearly as many fields as the Gulf of Mexico but they have found some big oil and gas accumulations.
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Re: Deep water oil

Unread postby Tanada » Thu 21 Nov 2013, 08:04:34

After the Deepwater Horizon oil spill in the Gulf of Mexico in 2010, the largest in U.S. history, there was a lot of talk about the possibility of offshore drilling being scaled back.

Instead, the opposite has happened. Since the moratorium imposed on deep-water drilling in the U.S. in May 2010 was lifted in October of that year, offshore exploration and drilling in the Gulf of Mexico has continued uninterrupted and taken on new momentum, as it has around the world. Today, deep-water drilling—500 feet or more below the surface of the sea—remains the next big frontier for oil and natural-gas production....

According to Norwegian oil and gas consultants Rystad Energy AS, deep-water production is expected to account for 13% of the global output of crude oil and natural-gas condensates by 2020, up from 10% last year.

In the U.S., offshore oil production from the lower 48 states, mostly in the Gulf of Mexico, is expected to grow 18% from its 2011 level by 2020, thanks to exploration as deep as 5,000 feet, according to the U.S. Department of Energy.
http://online.wsj.com/news/articles/SB10001424052702303442004579123560225082786

Until Pops bumped my curiosity on this subject I had thought GOM was basically an also ran because of all the Bakken/Eagle Ford Saudi America hype.

I should have known better.
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Re: Deep water oil

Unread postby ROCKMAN » Thu 21 Nov 2013, 20:50:45

ptarr - I think your oil window is referring to the oil generation window. Also it's a gradational transition. many deep and hot reservoirs contain NG and some significant yields of oil condensate. But 350F is pushing the limit. Also while heat is critical for down hole equipment the real limit is heat gain. A lot of equipment can handle those temps for a short time. Here's one reference show stable oil down to 300F: http://my.opera.com/wandererbynature/bl ... ml/3907824 From a source:

"There are three stages to oil formation. The first is called diagenesis. This stage involves the biological, chemical, and physical alteration of organic material before heating begins to affect it. The second state is the thermal alteration known as catagenesis. This stage generally takes place between 50-200 degrees C (122-392 F). The third stage is called metagenesis, and is high temperature alteration. It is also known as the gas window. It ranges above 200 degrees C.

The temperature required to alter organic material is produced by gradual burial and the geothermal gradient for the area of burial. As heat comes from the earth's mantle it warms the crust. Areas with thin crust have high heat gradients, while areas with thick crustal material have a slower geothermal gradient.

The oil window is often referred to as the period of time during which it is believed that a source rock was buried deep enough to cause catagenesis. The burial history is studied using several methods (including vitrinite reflectance values and bottom-hole temperature measurements) and this gives petroleum geologists some idea when oil might have formed in a particular basin. Combining this with understanding of what structural or stratigraphic changes have taken place, a prediction is made of where the oil might have migrated to, away from its source rock."
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Re: Deep water oil

Unread postby sparky » Thu 21 Nov 2013, 21:19:18

.
I was under the impression that the Brazil coastline was geologically identical to the African guinea gulf
the ocean floor proper is quite thin , really
as for the Abysmal plain most of it is new floor created by volcanism and continental drift

the sediment temperature change with the magma plumes underneath ,
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Re: Deep water oil

Unread postby rockdoc123 » Fri 22 Nov 2013, 20:29:29

Some clarifications:

Depth to oil window varies all over the place. Oil generation is a product of heat and time (governed by the Arhenius equation). Sediment that are quite young and buried deeply could still be in the oil window.....likewise sediments that were not buried very deeply but are very old can be in the gas window. More importantly coming into play is geothermal gradient, rock absorption or transmission of heat and the type of organic material (kerogen) that is the oil/gas precursor.
In response directly to Sparky's question heat gradients through the various crustal types are different. As an example in the thick older continental crust regions geothermal gradients are generally in the 10 - 20 C /km, in transtional crust near continental margins it can climb higher to around 45 C/km and in the young oceanic crustal areas heat flow can be much higher. As an example in the East African rift system where new oceanic crust is being formed due to thermal rifting heat flow can be higher than 110 C/km. Not far away in the sedimentary basins of Sudan, Kenya and Tanzania the heat flow is much lower.
Kerogen is something that is often overlooked. Kerogen of lacustrine (lake) origin is generally mainly Type I which takes much more heat/time to generate hydrocarbons than say a marine sourced kerogen of Type II.
Also what is overlooked is that as long as sediments are undergoing burial you can calculate the depth to various hydrocarbon windows if you know the temperature history, the burial history and the type of kerogen. But if those rocks are uplifted then you will see gas trapped in reservoirs that are quite shallow and source rocks that have possibly gone to dry gas that are also quite shallow. There are ways of reconstructing the uplift history to account for this, something basin modelers do all the time but the point is there is no general "depth to oil window" that can be applied across all basins.
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Re: Deep water oil

Unread postby Keith_McClary » Tue 26 Nov 2013, 03:48:40

A neighbour lady who was doing exploration off west Greenland told me anything under a billion barrels is not economic. How many offshore discoveries over a billion can there be in the world?
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Re: Deep water oil

Unread postby ROCKMAN » Tue 03 Dec 2013, 18:22:22

BIG LEASE SALE OF FLORIDA COAST

From RigZone: “As part of President Obama’s all-of-the-above energy strategy BOEM announced that it will hold Gulf of Mexico Eastern Planning Area lease sale 225 on March 19, 2014, immediately following the proposed Central Planning Area (CPA) Sale 231. Proposed Sale 225 is the first lease sale proposed for the Eastern Planning Area under the 2012 – 2017 Outer Continental Shelf Oil and Natural Gas Leasing Program, and the first sale offering acreage in that area since Sale 224, held in March of 2008. “This proposed sale is another important step to promote responsible domestic energy production through the safe, environmentally sound exploration and development of the Nation’s offshore energy resources,” said BOEM Director Beaudreau.

The proposed sale encompasses blocks covering approximately 465,200. The blocks are in water depths ranging from 2,657 feet to 10,213 feet. It is south of eastern Alabama and western Florida; the nearest point of land is 125 miles northwest in Louisiana. BOEM estimates the proposed lease sale could result in the production of 710 million barrels of oil and 162 billion cubic feet of natural gas.”
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Re: Deep water oil

Unread postby Tanada » Tue 03 Dec 2013, 23:43:14

The Florida lobby has always screamed about any possibility of leases within 200 miles of the 'pristine beach front property'. It will be interesting to see how they react to this proposed sale. Personally so long as the rigs are beyond the visible horizon I don't think Florida has anything to complain about.

Isn't there a kind of shelf on the west side of the Florida peninsula that gradually deepens as you go westward? IIRC from my geography classes way back when this shelf is as big or bigger than the part of Florida currently above sea level and much of it would have been swamp during low sea levels in the deep glaciation periods. Might be some good fossil fuel deposits in that kind of geological formation?
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Re: Deep water oil

Unread postby ROCKMAN » Wed 04 Dec 2013, 08:20:14

The GOM off the west coast of FL has long been a disappointment to the oil patch. The Destin Dome area became known as the “Dust-in Dome” alluding to a duster…a dry hole. But notice the water depths covered in this sale. It’s essentially a Deep Water sale. To some degree it’s on strike with the major DW fields off La….as well as the blowout at Macondo. I’m not sure what the potential is for this area: eventually every play dies out somewhere along strike. The bid numbers should be telling: if the oil patch thinks there a fair chance at some grease being out there they bid up the lease bonuses. One interesting aspect I saw in the article was the share of fed bonuses/royalty that went to the Gulf states…all of them EXCEPT FL.
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Re: Deep water oil

Unread postby Subjectivist » Wed 04 Dec 2013, 19:58:57

ROCKMAN wrote:The GOM off the west coast of FL has long been a disappointment to the oil patch. The Destin Dome area became known as the “Dust-in Dome” alluding to a duster…a dry hole. But notice the water depths covered in this sale. It’s essentially a Deep Water sale. To some degree it’s on strike with the major DW fields off La….as well as the blowout at Macondo. I’m not sure what the potential is for this area: eventually every play dies out somewhere along strike. The bid numbers should be telling: if the oil patch thinks there a fair chance at some grease being out there they bid up the lease bonuses. One interesting aspect I saw in the article was the share of fed bonuses/royalty that went to the Gulf states…all of them EXCEPT FL.


Learn something new almost every day on here, I always thought the western approaches to Florida in rhe GOM was unexplored territory.
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Re: Deep water oil

Unread postby ROCKMAN » Thu 05 Dec 2013, 09:46:37

sub - If you look at a geologic map the big conventional carbonate oil trends through Al and Miss. bend in the direction of the western offshore Fl area. Companies had high hopes of the trend continuing offshore. Big lease sales back in the late 70's out there but the state of FL blocked drilling for many years. Eventually the US govt had to return many $millions in lease bonuses to companies that were able to drill. I'm not sure that the area was drilled enough to condemn the potential of the area. Here are some details from a 2001 article:

Destine Dome: Drill bit penetrates the reservoir, and the tests are run. The result: Hydrocarbons are there all right -- just not in commercial quantities. High expectations are dashed, and vast amounts of at-risk money are lost. Maybe, just maybe there would be less hostility toward the industry that supplies the vital resources demanded by all if such not-uncommon E&P scenarios were better understood by the public-at-large.

Consider Destin Dome in the eastern Gulf of Mexico, a striking example of faded hopes and dreams and staggering sums of money risked and lost in the search for hydrocarbons. It has even been called "Dusty Dome" in impolite conversations about its past results. There's also the issue of perhaps as much as three Tcf of dry, natural gas that may remain trapped in the depths of the structure forever. The dome lies 25 miles south of Pensacola, Fla. The large, west-northwest trending anticlinal feature is more than 50 miles long and 20 miles wide and with a relief of 3,000 feet on Lower Cretaceous rocks. It apparently is the result of a salt swell that was uplifted during the Late Cretaceous and early Cenozoic. There's been a more-than-decade-long endeavor to develop the vast natural gas reserves discovered there, with nothing yet realized.

It's a political thing: Chevron acquired leases at Destin Dome in 1984, before #41 Bush imposed leasing moratoria off much of the Florida coast. The initial hydrocarbon discovery on the structure occurred in 1987 on Chevron's Block 56. In accordance with the Coastal Zone Management Act, Chevron submitted an exploration plan to both the MMS and the state of Florida, seeking approval to proceed with drilling operations. The plan was rejected by Florida, but the denial was overruled by the U.S. Commerce Department. After delineating the lease, Chevron submitted a development plan in 1996 and Florida responded with a resounding 'No!' -- so Chevron found itself once again in the halls of Commerce, where the issue remains unresolved today, after more than five years. On July 24, 2000, according to the MMS eastern Gulf of Mexico review data, Chevron and partners filed a lawsuit against the U.S. government for denying the companies "timely and fair review" of plans and permits and an appeal concerned with the Destin Dome 56 Unit. An MMS source noted that Chevron is seeking to recoup both the money already spent and the potential money to be realized on a find that large. Block 56 was leased in 1984 by Conoco, Chevron and Murphy Oil at a cost of $1.6 million.

The Infamous Failure: Destin Dome emitted a different kind of siren's song in the early days of Gulf exploration, when industry was looking at shallower potential prior to the big Norphlet play activity that began close to shore and eventually migrated offshore to the structure. "There was a big lease sale in the early '70s," said Layton Steward, "and everybody was bidding on it." He noted that natural gas wasn't worth much then, so Shell went after a tract downdip from the crest hoping to find an oil leg instead of gas. "This was a huge-but-late structure geologically, and it had us worried a bit relative to the migration and entrapment of hydrocarbons on it," Steward said. "Exxon and Champlin pretty much bought the whole thing," he added, "and a bunch of the Champlin guys, including the senior-most executives, were fired because they so overbid the sale. Exxon drilled a well at Destin Dome Block 162 in 1974, kicking off the first exploratory drilling activity in the eastern GOM. Two years and 15 dry holes later, exploration came to a halt, according to MMS data. Three lease sales were held in the area during the '80s, when industry interest was rekindled.

The proposed highly-controversial Lease Sale 181 will be the first in the eastern GOM since 1988. Following months of mud-slinging rhetoric and more emanating from the NIMBY (Not In My Back Yard) citizenry in Florida, their elected officials and others, the initial sale area of 5.9 million acres has been reduced dramatically to 1.5 million acres, all of it at least 100 miles from the Florida coast. Florida's neighbors are not too happy over the results of the Sunshine State's fight to keep offshore drilling at such great distances from its condo-blighted, yet so-called pristine beaches. U.S. Representative Sonny Callahan, R-Ala., chairman of the House Energy and Water Development Subcommittee expressed his anger in a unique way. He added language to a House spending bill that could halt construction of a major new natural gas pipeline running from Alabama to Florida that would enable Floridians to reap the benefit of production from its neighbor's backyard. The proposed sale, which will be the eleventh sale on the OCS in the eastern GOM, is tentatively scheduled for Dec. 5.
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Re: Deep water oil

Unread postby Tanada » Thu 05 Dec 2013, 22:13:18

Hey Rockman, part of that reads like you wrote it to explain the situation and part of it looks like a quote about the history of the area, but the two are mushed together and I can't tell where one ends and the other begins. Maybe I am just foggy today, but could you explain it in smaller words for my tired brain?
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