I'm wondering whether there can be prosperous oil wells on (active)
volcanic islands, and if so, whereabouts on the island they would be
located (i.e., near the volcano crater, or nearer to the beach).
Please post all the information you come across, no matter how
irrelevant it may seem, as long as it is coming from reputable
scientific and news sources. Thank you. If you have to draw diagrams
in order to demonstrate or clarify, I will refund your additional time
and effort. Thanks!

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Clarification of Question by rowl-ga on 13 Mar 2003 06:33 PST

I am not interested in specific islands, just in whether this is
theoretically possible and how it would look like.

Hi, that's a good question! I was picturing the lava igniting the oil
or something!

But in fact, the short answer to your question is: no. A truly
volcanic island is made from its own lava activities (Hawaii is a
string of such islands) and so the rock is layer upon layer of igneous
rock. This precludes or makes impossible the conditions needed for oil
formation, which are the layering of organic material between layers
of sedimentary rock, that then squeeze it and let it break down into
crude oil. There are no layers of sedimentary rock within an actively
formed volcanic island.

To cover some possible peculiarities (earth's geology is nicely
complicated at times), you might actually find areas where volcanic
lava pours over older sedimentary rock, under water, which might by
luck have pockets of oil in the gaps and pores there, but this might
not be what you really suggest in your question (a volcanic island).
One example of a study of igneous/sedimentary interlayering, though
not a volcanic island, can be found at the Brazilian "Revista
Brasileira de Geociencias report on rock in mainland Sao Paulo found
here:

http://www.sbgeo.org.br/rgb/vol30_down/3001/3001082.pdf

Iceland is a huge lava-based sland (formed by the mid-Atlantic rift
rather than a classic volcano) and when they do drilling there, it is
only for hydro thermal purposes, as mentioned in A Tour of Some
Iceland Geology, by Dr. Robert M. Stesky at:

http://www.pangaeasci.com/_iceland.htm

Another volcanic island (no longer active) is St. Kilda off the
Scottish coast, and a site describing its geology is Explosive
Beginnings at:

http://www.kilda.org.uk/explosive-beginnings.htm 

And another site showing the proximity of such lava-based structures
(note the seamounts on the 1999 RSG Newsletter map at:

http://www.rsg.ie/rsg/rsg_news.pdf

This shows large sedimentary beds nearby, which are thought to contain
some oil reserves, but are not related to the volcanic activity that
created nearby St. Kilda and others. What I mean by all this, is that
you might find volcanic islands mounted over or near sedimentary beds,
which could (in theory) contain petroleum, but that the actual
island/sea mount will not contain any oil, since it was formed by
molten rock.

You can confirm some of the basic geological principals at the
wonderful site Ainakumuwai which gave these credits: 'Ainakumuwai :
Ahupua'a of Nawiliwili Bay' is a sabbatical project funded by the
Department of Education, State of Hawai'i. It is found at:
 
http://www.hawaii.edu/environment/ainakumuwai/html/ainakumuwaiislandformation.htm

In summary, truly active volcanic structures such as volcanic islands
are incompatible with the sedimentary build-up needed for
oil/petroleum formation. But nearby or much deeper subterranean
sedimentary rock (below the lava) can be associated with the islands,
yet only secondarily. I could not find, in what time I could afford to
devote here, any association of significant (indeed any) oil reserves
drillable from within a volcanic island itself.

I hope that's some help. If you need a clarification, please let me
know, and I'll zero in on your particular need. Thanks for using
Google Answers

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Clarification of Answer by lmnop-ga on 13 Mar 2003 08:47 PST

My search terms were these:

volcanic island geology
petroleum exploration volcanic island
volcanic sedimentary geology

These led to a link or two which opened up into the huge world of
geology sites, often associated with college course work on line.

You're a magician with the search engine, Imnop! Thanks!

I was going to post this as a comment earlier but somebody got to the
questionm while I was typing.  However I am going to post it anyway in
light of the answer given which has been excellently researched..

There is a "trick" element to your question which you may not realize
is there or even a researcher may not realize is there.  Can there be
oil wells on a volcanic island (whether or not they are prosperous
would be subjective) - the answer is 'yes.'

It seems your question relates to the location of wells rather than
the actual production and availability of oil within a specific
geologic setting.

So how can there be oil found in a place which by its very nature
prohibits the production of oil?  There can be oil nearby which is in
different rock strata and type and petroleum may show on a volcanic
island as migratory "seeps."  However, these seeps are not sufficient
to warrent the drilling of a well.  Because of the convenient location
of the oil to the island, a well can be side drilled or angle drilled
(directional drilling) from a site on the island into a nearby
non-volcanic area where oil is located.  A good example of
"directional" drilling is found in Southern California where wells
hidded in disguised structures within the city of Los Angeles are
tapping oil far out at sea in Santa Monica Bay.  That is why I say a
well 'can' be located on such an island even though the oil being
tapped is not a part of, or product of, the island itself.

That is why I mentioned the "trick" part of the question.  Volcanos
cannot produce oil but may be located close enough to non-volcanic oil
reserves to make certain types of drilling feasible.  So if somebody
is trying to sell you a limited partnership in an oil well on an
erupting island, don't laugh.  It may be quite valid.

Cheers
digsalot

FYI:  In New Zealand, a country with substantial vulcanism, there is a
province named Taranaki.  It is dominated by a huge dormant volcano,
Mt Egmont (aka Mt Taranaki).  It is also an area rich in fossil fuel
reserves, and natural oil seepage is known.  Off-shore from this area
is a very extensive gas field.

Thanks a lot, guys! The info on directional drilling and Mt. Taranaki
is extremely helpful. Now I can devote my time to researching these
things further, which is much more fun than trying to find out exactly
WHAT to research in the first place. Thanks again! I wish I could tip
you!

The New Zealand example, though not a volcanic island by itself, is a
wonderful example, and many thanks to that researcher. Here's a very
good, slightly technical site with an illustrated pdf of the strata,
etc. for this area, in an article called Petroleum system of Northern
Taranki Graben by GP Trasher, B Leitner, and AW Hart:

http://www.med.govt.nz/crown_minerals/petroleum/docs/nzpconf-2002/21thrasher.pdf

This is also not an extinct volcano, as it has erupted less than 300
years ago and is still an active area. The proposed drilling for oil
there will go through igneous rock to get to the oil bearing
sedimentary rock, so in that sense, it really is a great example of
the latter part of my original answer where volcanic rock overlays
sedimentary rock. That would be quite possible even for a true
volcanic island, as well, though again I couldn't find that it is
actually true anywhere.

But it's possible, which is what I needed to know. Wonderful! You have
no idea how welcome all this information is. Unfortunately the text
within Figure 5 in the PDF document is illegible, but the website
itself seems to be worth browsing, too.

You might like this too - an image of the Maui off-shore rig with Mt
Taranaki in the background.

http://www.focusnzphoto.co.nz/Focus/thumbnails/CMEP08.jpg