Adrok – find hydrocarbons with dielectric resonance
Feature Articles, Jan  29  2010 (Digital Energy Journal)

- Adrok Group of Edinburgh, UK, has developed a remarkable technology which can gain an understanding of the subsurface using dielectric resonance (which roughly means, measuring how different materials respond to radio or microwaves which are passed through them).

The technology has already been used by BG Group, Caithness Petroleum and Medco Energy. BG is not revealing where in the world it has used the technology, but was pleased enough with it to consider taking it to another part of the world, says Gordon Stove, managing director of Adrok.

Adrok has already tested the equipment in volcanic regions in Scotland, in the deepest onshore site in Scotland, in deserts in Oman, in the Canadian Arctic circle, and offshore. It has collected data from rock as deep as 4km, and tested its results against what is known to be underground at that depth from boreholes.

The technology works by learning how different substances - including hydrocarbons – interact with the light waves which pass through them (and are then reflected back to the surface) . After ‘training’ the tool in areas where you know what the geology is (working out how different types of rock interact with the wave), you can then use it to understand unknown rocks.

Adrok is not the only company working with dielectric resonance – also HP, MIT, NASA, Imperial College, Demontfort University are conducting laboratory experiments, Mr Stove said.

Robert Kennedy, CEO of Caithness Petroleum Ltd, in a comment from the audience at the Finding Petroleum Exploration Technology and Business conference in London on Jan 20-21, said his company had used the technology successfully in Morocco. “Once you teach the equipment what a gas field is – it can actually find a gas field,” he said. “I’m working on plans to cash in while the going is good.”

The system identifies molecules but cannot identify how much of a certain substance is present, “so a small amount of gas can be confused with a large gas field,” Mr Kennedy said. “That’s a problem we had initially which I think we’ve largely overcome.”

Caithness Petroleum asked Adrok to do a test on a known region and identify where it thought there would be oil and gas – the results were than compared to actual known oil and gas reservoirs. “We proved we could find gas in the ground very accurately,” Mr Stove said.

Mr Stove showed well logs, comparing where Adrok predicted gas would be, where geological analysis predicted gas would be, and where gas was actually found according to well logs (To see the image click on 'presentation from Finding Petroleum conference' below and go to slide 22).

The gas reservoirs were at depths of 750m – Mr Stove reckons that his technology predicted their locations to within 7m. “The client was very happy,” he said. “He concluded that the technique had successfully predicted where the gas was.”

“I’ll give you a simple test,” said Andrew Lodge, exploration director of Premier Oil, in the audience of the Finding Petroleum conference. “I’ve got 3 km of overburden that I know roughly what the rocks are, but not absolutely. Can you tell me if I’ve got hydrocarbons [beneath them]?”

“Yes”, Mr Stove said.

The company was founded in 2000, and spent 8 years developing the technology, including developing the theory and building prototypes. Around £3m was invested over this time, mainly from management but with some government funding. It was commercially launched in mid 2008.

The system was developed by Dr Colin Stove (Gordon Stove’s father), who worked as a principal investigator for the European Space Agency and NASA, and invented principles of atomic dielectric resonance.

The system

In more detail, the equipment sends a narrow beam of energy into the ground – like a laser pointer – which is reflected back by the various rock layers, with the energy changed by the materials it has passed through on the way. It can reach a depth of 4km. The microwave does not need to go directly into the ground – it can go in at angles.

The system measures the resonance of the rock (how it oscillates at different radio wave frequencies) and how much the rock reflects the light wave.

Once the system has been trained, it gives absolute answers – so is not subject to the vagaries of interpreting, where different geologists can give a different result.

The equipment comprises two antennas (for transmitting and receiving), and two boxes of electronics (one to manage the creation of the wave, one to analyse the received signal).

The equipment all fits in about 7 small cases – so it can be carried with personnel on an aeroplane as excess baggage, which saves time and hassle, Mr Stove says.

Calibration

The biggest challenge to begin with was calibration – in order to understand the data gathered in the field, it is first necessary to know which types of rocks which give off which kinds of signatures.

The ideal situation is if there are outcrops of the rock under question, so direct tests can be made on it.

However Adrok has been gradually building up a database of different rock signatures, and believes it is close to the point where the company can do a survey of rock it knows absolutely nothing about beforehand and come up with useful results.

Adrok has been testing as many different rock types as possible, including going through core stores, and also drilling rocks.

Doing a survey

If it is asked to do a survey for a client, Adrok can start off by making an assessment about whether it thinks the technology will actually work on that geology. “If we don’t pass this stage we don’t go any further – we’re open and honest with our clients – we stop there,” he said.

If a decision is made to go to the next stage, Adrok will then try to get as many opportunities as possible to ‘train’ the equipment on known rocks which are similar to the rocks in that location.

All of the equipment needed to do a survey can be driven to the site on a Land Rover. A strip of land about 100m long is needed to do the survey.

Individual surveys of a specific site take about 2 hours, so it is possible to do 5 surveys in a day. Then it takes about 3 days to process the data.

The scans can either be directly downwards (to find out about rock beneath the scanner, similar to if you actually drilled a well downwards, or you can do a wide angle scan of a wider area.

The output data is quite simple – Adrok believes that there are hydrocarbons at a certain location, and at a certain depth. It provides a deterministic answer, not a probability.

The data can also be imported into earth model databases, including Petrel, Petris and Kingdom.

Mr Stove reckons that the system could prove most useful in ‘appraisal’ stage – getting an alternative view of what is happening in the subsurface – to give oil companies additional information before they make a decision to start drilling.

Future developments

In future, Adrok would like to be able to pinpoint rock properties more precisely, and work out properties such as density and moisture content.

It is also considering developing an airborne version of the technology. Radio waves are already used for telescopes, sending waves from the ground to the moon – so there are no obstacles to sending them through the air or space.

Adrok

Presentation from Finding Petroleum conference

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