Oil sector faces seismic changes

• Last Updated: June 07. 2008 11:17PM UAE / June 7. 2008 7:17PM GMT

Hills of black gold: much of the countryside is empty but new technology which can map underground areas for oil four-dimensionally could radically change the landscape, just as it already has in other parts of Abu Dhabi. Andre Forget / The National

The potential peak oil crisis that is dominating headlines around the world has been “just around the corner” for decades.

In 1974, academics posited that global oil production would peak in 1995. When that did not materialise, others set their sights on 2008, or 2010, as a target date.

But the oil industry has long maintained that it can use new technology to get a higher proportion of existing reserves out of the ground. Advanced well mapping and drilling techniques, they say, could put off that fateful day for decades to come.

On Wednesday, for example, BP announced that it had successfully extended the peak life of its oil field in Azerbaijan by several years – and 3.5 billion extra recoverable barrels – with new technology and more drilling platforms.

As the UAE’s great oil fields begin to enter their middle years, geophysicists here will have to make use of these technologies that can see deeper and more clearly into the earth to keep the oil flowing.

Producing crude in Abu Dhabi so far has been a matter of locating giant fields and drilling a well, said Karl Berteussen, acting director of the petroleum geosciences department at the Petroleum Institute in Abu Dhabi.

“In the beginning, it was very easy,” he said. “They grew up with it, they never had to find it.”

Abu Dhabi is now looking to increase its oil production capacity and develop new gas fields, at the same time as maintaining output at its existing fields. In order to manage these resources in the most efficient way possible, and to potentially locate new deposits, the country will have to make use of more sophisticated versions of seismic survey, in which waves of sound are directed into the ground and measured to detect the presence of oil.

But modern-day seismic is an elaborate and expensive undertaking.

Last autumn a three-dimensional mapping of the Shah field near Liwa was finished by the Abu Dhabi National Oil Company (Adnoc). The operation required 350 people to work, over the course of several months, to map 1,200 square km. In total Adnoc said it has mapped 50,000km of two-dimensional seismic and 30,000 square km of three-dimensional seismic.

A seismic operation on fields bigger than Shah could easily require up to 10,000 seismic vehicles, Mr Berteussen said.

At a basic level, seismic mapping is quite simple. It relies on the principle that sound waves travel at different speeds through underground substances and reflect off certain materials.

An initial sound wave is directed into the earth, traditionally by a dynamite charge, but now more often by vibrator lorries, which stand in one place and vibrate for 10 to 30 seconds.

The sound waves travel many metres down into the earth, through sand and carbonate rock, salt caps and, ideally, crude oil or natural gas. Receiver lorries positioned in lines at set distances from the vibrator or dynamite detect the reflected sound waves, and, based on the amount of time it takes for the wave to get back to the surface, develop an idea of what kind of substances are located underground. At the simplest level, the data is compiled in lines, called two-dimensional seismic, which allow engineers to look at cross-sections of the Earth.

It is much more common now, however, to repeat the process over and over from various angles at different points across a wide area, so that engineers can develop a three-dimensional digital image of a region, either to determine prospects for new discoveries or map existing reserves of oil and gas.

The digital image of the field is colour-coded to differentiate between substances. Engineers can rotate and spin the model on screen, identifying optimal places to drill or, in the case of ageing wells, inject water or gas to increase pressure.

The most recent development has been with the so-called “four-dimensional” seismic, which is a fancy way of saying engineers survey a hydrocarbon deposit periodically for several years. Incorporated into a model, the time-lapse image can show distribution of the oil and how it flows over the life of a well.

Mr Berteussen, who is from Norway, said four-dimensional seismic survey was a prime reason why Norwegian engineers have continued to squeeze an unusually high proportion of oil from older wells.

“It’s an essential part of why we are up to 60 per cent,” he said.

Recovery rates depend on many factors, including the properties of the oil and rock underground. But rates below 50 per cent have been normal even on the largest fields unless secondary recovery methods, such as injecting gas to maintain pressure, are employed.

Seismic survey is not the only technology available to map fields. Engineers can make use of gravitometers, which measure the Earth’s gravity very precisely at a single point on the surface. If an oil or gas field is located beneath the ground at that point, the gravitometer will register slightly less gravity.

A newer technology in use worldwide is electromagnetic survey. The equipment, which is being tested by Adnoc, measures how well geological structures underground conduct a varying electromagnetic current produced on the surface. Each type of rock, liquid or gas underground conducts the signal differently, allowing engineers to distinguish between types of liquid and avoid drilling an expensive hole into a plain-old aquifer.

Mr Berteussen said advanced seismic technology remains the sharpest tool in engineers’ search for oil.

“It’s the technique that can best describe the underground,” he said.

A seismic operation at sea works the same way as on land, but is less expensive, because a single ship can drag behind it a string of detectors, reducing the amount of manpower needed. The stakes are higher, however, because drilling a hole into the sea bed is much more expensive than on land.

Simple seismic exploration has been a mainstay of the oil industry for many years. Seismographs, which had been used since the 19th century to detect earthquakes, were first put to work in the American oil industry in 1923.

The first technology, which originally used dynamite charges to generate a sound wave underground, allowed explorers to locate underground salt domes, which often form the “cap” of an oil or gas field. But the technology quickly developed as computers allowed seismologists to more precisely measure the seismic waves and compile thousands of data samples into comprehensive models.

In his office at the Petroleum Institute near the Maqta Bridge, Mr Berteussen holds up a small cylinder of sandstone. Pulled from the bed of the North Sea, it looks and feels like solid rock. Immersed in a lake of crude, however, it’s a sponge that soaks up 30 per cent of its weight in oil.

Mr Berteussen holds up another sample, this one from the UAE. It’s called carbonate, and it is heavier and noticeably blotchy, composed of materials of varying type and density bonded together.

The carbonate is less porous – five to 20 per cent compared to 30 for the sandstone – but more importantly it is also not uniform in composition and therefore much less predictable in how oil and water flow through it as a well ages. Petroleum geologists call this quality “permeability”.

“The rocks here are harder,” he said. “It’s difficult to describe with seismic.”

Poor permeability requires advanced technology and can be a risky bet. Mr Berteussen recalled that several years ago, engineers on Sakhalin Island off the east coast of Russia drilled a well in a region with highly impermeable rock, against the advice of many geologists. The oil gushed out, much to the drillers’ delight, but for only 10 minutes.

It will take a lot of research and new technology to keep Abu Dhabi’s wells pumping at full capacity in coming years, he said.

“They have a lot of research to do,” he said. “Frankly I think there have been a lot of technologies that have not been tested here.”

For many geophysicists, nanotechnology, the use of very small robots and sensors, will be the next big development in mapping oil and gas wells. Scientists imagine that one day soon, engineers could pour thousands, or even millions of tiny sensors into a reservoir, which would spread out to every corner and crevice like tiny beacons, allowing computers to generate an exact picture of the reservoir.

The technology remains the ultimate goal of oil data research, said Peter Venn, the Middle East business development director for SAS, which sells data-crunching technology to the region’s oil companies.

“If you put nanobots in there – imagine getting the perfect size of your reservoir understanding down to the nth degree,” Mr Venn said.

Last month, Bahrain-based Arbah Capital launched a nanotechnology investment fund that would focus in particular on the oil, gas and petrochemical industries.

In the meantime, however, Mr Venn suggested better compiling of information from seismic and other sources, combined with improved computer modelling, could help national oil companies extend the lifetime of wells in the GCC. “For us, it’s not much about increasing production right now, it’s about increasing the lifetime of a field,” he said.

Half of a seismic operation occurs in the field, on detection lorries and ships. But the other half occurs back at the office, where computers compile data and generate hundreds of forecasts and simulations. Investments in better seismic equipment, improvements in software, and more skilled workers could increase efficiency markedly, he said.

This technology could increase the efficiency of oil production by two, three or four per cent, said Mr Venn.

“We’re talking either about taking extra barrels out of the ground or expanding the lifetime of the field,” he said. “And this is real money.”

cstanton@thenational.ae