[Marxism] oil drops

Les Schaffer 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.

les schaffer

==================

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 
embarassing shortfall.

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 
existing sources.

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 
the reservoir.

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 
underground reservoirs.

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 
trick best.

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.

High pressure
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 
viscosity5.

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 
demand.

JIM GILES






More information about the Marxism mailing list