When one discusses oil, it is good to understand the "mother" of all oil fields, Ghawar, in Saudi Arabia, the largest oil field in the world.
To give some historical perspective, Ghawar was discovered shortly after WWII in 1948 and began producing in 1951. Even after all that time it still produces more oil than any other field in the world. Ghawar has produced a cube of oil 19 miles high, which is roughly 99,000 feet high (think of those airliners you see at 33,000 feet high and increase that three times, that's a whole heck of a lot of oil).
As described formally, Ghawar is situated over an active fault system (see link below quote):
http://www.searchanddiscovery.net/docum ... /index.htm
Ghawar is a large north-trending anticlinal structure, some 250 kilometers long and 30 kilometers wide. It is a drape fold over a basement horst, which grew initially during the Carboniferous Hercynian deformation and was reactivated episodically, particularly during the Late Cretaceous. In detail, the deep structure consists of several en echelon horst blocks that probably formed in response to right-lateral transpression. The bounding faults have throws exceeding 3000 feet at the Silurian level but terminate within the Triassic section.
What is interesting about the, above, passage is that while Ghawar is described as "over a basement horst...and was reactivated episodically...[and] the deep structure consists of several en echelon horst blocks...", the, above, passage makes no link between this active basement structure and the ultimate source of the oil (perhaps, the conventional view blinds the author to this connection).
Others, however, have made this connection explicit:
The oil fields of Saudi Arabia sit atop one of the most robust tectonic fracture and fault networks in the world. According to one study's author, H. Stewart Egdell, "Basement horst [a block of the earth's crust seperated by faults from the adjacent relatively depressed blocks] that has been periodically reactivated, underlies the world's greatest oil field, Ghawar."
These oil field structures are mostly produced by extensional block faulting in the crystalline Precambrian basement along the predominantly N-S Arabian Trend which constitutes the 'old grain' of Arabia. This type of basement horst, which has been periodically reactivated, underlies the world's largest oil field, Ghawar, and other major oil fields, such as Khurais, Mazalij and Abu Jifan. The basement horst beneath Ghawar Anticline has been suggested by Aramco (1959), from a positive Bouguer gravity anomaly which practically mirrors the field, and more recently, in greater detail, by Barnes (1987).
All Saudi Arabian offshore oil fields, and some near coastal fields, such as Abu Hadriya, Abqaiq and Dammam, are also produced by basement faulting which has cut the saliferous, Upper Precambrian Hormuz Series, triggering deep-seated salt diapirism.
(See, Basement tectonics of Saudi Arabia as related to oil field structures, by H. Stewart Edgell:)
http://pagesperso-orange.fr/brcgranier/ ... l_1992.htm
Again, note the reference to "reactivated" basement horst.
What does "periodically" or "episodically" reactivated mean?
Here's an analogy: Think of a glass of ice water with regular little ice cubes floating at the top; you jostle or agitate the drink and all the cubes slosh around and then reform a network of interlocking cubes. During the jostling, fluid is able to move up and around the cubes as they collide with each other.
Strike-Slip Fault Zone, Pop-up Block, Uplift, Detached Megablock, Extensional Block Faulting, Thrust Sheets, Fold-over, Lithotectonic, Thrust Fault, Regional Faults vs. Local Faults, Horsting, Fissures, Fractrues.
What do all these words have in common?
These words describe geologic structures on the edges of tectonic plates where collisions and interations take place. These words are the basics in understanding the interaction of the earth's crustal geology.
But they are also words used over and over in the exploration & discovery of petroleum. You just about can't read technical data about areas of potential oil discovery or production without these words.
Turns out, as has been previously commented and linked to, and as the title of one study indicates, the majority of the world's giant oil fields are located above where tectonic plates collide, fault, and fracture. Giant oil fields contain 65% of the world's proven reserves, and it starts off with the biggest oil field of them all, Ghawar.
Apparently, before the recent price collapse, Middle East oil producers were confident that they could raise oil production by 10 million barrels a day (see link below quotes):
http://www.gulfnews.com/business/Oil_an ... 43278.html
Dubai: A massive $300 billion investment in boosting oil production is underway which could see the Arabian Gulf deliver a staggering 10 million barrels of crude a day in added capacity by 2015 more than half from Saudi Arabia alone according to project research firm Proleads.
"Recent analysis of total global oil production and development projects indicate that world crude production capacity from all sources has the potential to rise from 87 million barrels per day to as much as 108 million by 2015," said Emil Rademeyer, director of Proleads.
Seems the Middle Eastern oil producers don't believe they are running out of oil anytime soon.
Abiotic Oil theory.