[Marxism] oil drops
schaffer at optonline.net
Wed Jun 16 14:15:15 MDT 2004
I am sure MJ would have told us just how costly these measures are for
extracting remaining oil reserves from existing wells. But the article
is worth a read for description of contemporary __prototype__ methods.
Nature 429, 694 - 695 (17 June 2004); doi:10.1038/429694a
Oil exploration: Every last drop
The price of petrol is going up and new oil discoveries are declining.
Can underground fires and hydrocarbon-hungry bacteria keep the oil
flowing? Jim Giles finds out.
Cheap oil is on the way out. This has been made abundantly clear in
recent months thanks to security problems in Iraq and terrorist attacks
in Saudi Arabia — both countries with massive crude-oil reserves.
Markets are unsettled and prices at the pump are soaring. Last month the
price of crude reached more than US$42 a barrel, its highest for 20 years.
But geologists have known for years that the end of cheap oil is in
sight. Since the 1960s, the rate at which new wells have been discovered
has been on the wane1. Forty years ago, more than 50 billion barrels of
oil could be discovered in a single year. Today, finds of about 10
billion barrels per year are far more common (see graph), many of them
from smaller fields. In short, many experts think that all the big
gushers — the wells that spew out masses of oil cheaply and easily —
have probably been found.
The decline has hit at least one oil company hard. Earlier this year,
the Anglo-Dutch oil giant Shell was caught in a media storm after it
admitted that its proven reserves — the oil the firm knows it can
definitely extract — are 20% less than its previous estimates. Reserve
estimates are often optimistic, analysts say, and many wells don't quite
produce as much oil as expected. But new wells are usually found, making
up the numbers. Analysts suggest that in this case Shell didn't find
enough new wells to make up their accounts, drawing attention to the
Shell's misfortunes and the situation in Iraq may change. But these
effects are over-lying a trend that cannot be ignored. Oil companies now
realize they cannot rely on finding new fields in the long term.
Instead, they will need to extract every last drop they can from
A slew of speculative techniques, from lighting fires in oil fields to
using microbes to help wash out oil reservoirs, are already available to
do this — and more are on the way. Some methods have been in development
for decades. But only now is the price of oil becoming high enough to
make them commercially viable.
"In the United States alone there is 355 billion barrels of oil that is
not recoverable using existing techniques," says Betty Felber, a senior
petroleum scientist at the National Energy Technology Laboratory in
Pittsburgh, Pennsylvania. This is more than 15 times as much as the
proven reserves that we can get at using conventional methods. "More and
more people are applying these technologies," she says.
"We say oil is running out, but 60% of it is left in reservoirs," adds
Malcolm Greaves, a geophysicist at the University of Bath, UK. "What are
we going to do? Walk away?"
Greaves is pioneering one radical solution: setting fire to the
reservoir. The technique was first trialled, albeit accidentally, in
Russian oil fields about 50 years ago. Engineers pumped air into
reservoirs in a bid to raise the pressure and force oil out of existing
wells, and discovered that the air reacted with and ignited the oil. The
combustion, which was limited to a small area of the reservoir, heated
the oil, reducing its viscosity and allowing more of it to flow smoothly
out of nearby wells.
The method, known as in situ combustion, has since been tested more
rigorously, with mixed results. Greaves estimates that about 140 pilot
projects were run during the 1980s, when oil prices were also high. Some
suffered from 'blow-backs' — explosions that travelled back up the well
through which the air was injected into the reservoir. In around a third
of the experiments, oil flow was not increased as much as anticipated,
in part because the injection well was often too far away — typically
hundreds of metres — from the producing well.
Fire down below
The technique could be rehabilitated if a large-scale trial set to start
this December is successful. Under scrutiny is a variant of in-situ
combustion known as toe-to-heel air injection (THAI), developed by
Greaves and his colleagues at the University of Bath2. As the wells are
being drilled especially for the trial, they are designed to be just a
few metres apart — avoiding some of the problems of previous trials.
Another new feature of THAI is that the oil is drawn off through a pipe
that runs horizontally, rather than vertically, through the reservoir.
This means that the fire can move along the pipe, says Greaves, pushing
oil out in front of it.
Greaves reckons that the US$30-million trial at the Christina Lake oil
field in British Columbia, Canada, could recover around 80% of the
billion or so barrels of oil in the field — an ambitious estimate given
that no more than 60% of a reservoir's field can normally be extracted.
The THAI tests, run by the Canadian company Petrobank, of Calgary,
should also prove useful in extracting Christina Lake's more viscous
oil, made up of heavier, larger molecules. The combustion will split the
oil, allowing the lighter and more valuable components to flow out of
For fields that already contain lighter oil, Egil Sunde has an
alternative3. A marine biologist by training, Sunde has worked for
Norwegian producer Statoil for around 20 years. "My idea was to use
Nature's ways," he says. Some microbes feed naturally on hydrocarbons.
These bacteria are already used to help strip oil from polluted beaches,
he points out, so perhaps they could also help pull it out from
Sunde is using microbes that both feed on oil and make it less sticky.
Oil is difficult to extract from half-empty fields, in part because it
clings to the pores in the reservoir rocks. Water can be pumped in to
help push out the oil, but eventually it will simply flow over the top
of this residue.
Sunde's microbes grow at the interface between oil and water in the rock
pores. This helps water molecules grab onto the oil and detach it. "This
makes the oil move more easily through the pores," says Sunde, who for
commercial reasons won't reveal the species of bacteria that do the
Statoil has been testing this idea since 1991 and was sufficiently
encouraged to start a commercial-scale trial in 2001. Bacteria grown in
Sunde's lab are now being pumped, together with nutrients and oxygen,
into reservoirs in the Norne field off the coast of Norway. Sunde says
it is too early to judge the results of this larger trial, but hopes
that it will eventually increase the amount of recoverable oil —
estimated to be around 530 million barrels — by about 5%.
The technique will not work in every oil field — the pores in the chalk
reservoirs of many Middle East fields are too small for bacteria to pass
through easily, for example. But industry observers are cautiously
optimistic about the technique's potential in sandstone reservoirs like
those in the North Sea. "This has a big future," insists Sunde. "It
could revitalize thousands of fields."
So far there only a few techniques such as Sunde's and Greaves' are
ready for large-scale trials, but other fledgling techniques could
mature soon. "They will become appropriate now that the oil price is
high," says David Hughes, principal reservoir engineer at Reservoir
Management Limited in Aberdeen, UK.
The UK-based energy company BP, for example, is investigating the
chemistry that governs the reaction between water, oil and reservoir
rock. Researchers there think that decreasing the salinity of the water
could prevent oil drops from becoming trapped in the pores4.
Other researchers think that plugging holes in the rock with plastic
will make it easier to build up water pressure with injected fluid.
Another way to increase the pressure and force out the oil could be to
use gas-producing microbes. Even more speculative ideas are being
pursued, such as using microwaves to heat up the oil and lower its
But the enthusiasm needs to be taken with a pinch of salt. Oil companies
tend to hush up unsuccessful projects, points out Nigel Brealey, also at
Reservoir Management Limited. In the early days of in situ combustion
projects, he says, the fire sometimes broke through into other wells and
caused explosions. "But it wasn't well reported," adds Brealey, "People
don't talk about failures." Techniques that look good on paper can also
fail to make economic sense in the field. Despite years of work,
unconventional methods such as microbial extraction produced some 2.8
million barrels of oil per day in 2003 — just 3.5% of the global total.
That percentage will, however, almost certainly rise as the price of oil
increases. The techniques will not make oil cheaper, but they will keep
help keep it flowing as new discoveries dry up. The days of easy oil
extraction may be over. But while there is money in it, techniques to
pull the last drop of the black stuff from the ground are going to be in
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