Russian engineer Alex Barak has been coaxing oil out of the ground for a long time.

Seventeen years ago, he was responsible for work at a particularly troublesome oil field in Kazakhstan.

"That oil field, Karazhanbas, was a real dog," he recalls, explaining that the oil there was very viscous, making it difficult to extract. "Nobody wanted it."

But Mr Barak and his colleagues persevered, drilling hundreds of wells. The field was later sold in 2005 for around $2bn (£1.5bn), he says.

Now, Mr Barak has turned his attention to the Wardlaw oil field in Edwards County, Texas. It lies in the southern corner of the Permian basin, a huge sedimentary basin in Texas and New Mexico that is associated with a high number of oil deposits.

But while there are an estimated 168 million barrels at Wardlaw, only around 120,000 have ever been extracted. That's what Mr Barak and his colleague Anatoly Bazhal, principal science coordinator, hope to change.

At Galex Energy Corporation, they have developed various technologies designed to dislodge hydrocarbons from the rock and move them to the surface.

One example of their innovations uses acoustic waves that are "swept", a process invented by Galex in which the waves are transmitted into oil-bearing rock surrounding the oil well.

Oil is trapped within that rock in tiny pores - the "reservoir" is more like a hard, wet sponge than an underground lake. To force oil out of the pores, the acoustic waves produce micro fractures in the rock that increase permeability.

The area is also exposed to cycles of low and high pressure. During low pressure cycles, the trapped oil droplets are impacted dramatically.

"The liquid bursts into vapour within the pore," explains Mr Barak. The pressure differential then encourages the hydrocarbons to flow towards the well where they can be drawn out of the ground.

Galex hopes to drill around 25 test wells this summer to measure the effectiveness of swept and other technologies it has developed.

But the process is not without risks. In a 2013 article Mr Barak and Mr Bazhal wrote, "the unauthorized and incompetent use of [the] technology swept can cause damage to the subsoil environment, property and threat to the life of staff".

Nevertheless, oil and gas companies are continuing to pursue new methods and techniques like this in order to get ever more fossil fuels out of the ground.

It's important to note that, traditionally, it has been commonplace for firms to recover only about a third of the oil from an oil field using existing techniques. But that is changing.

There are various reasons why new extraction methods are cropping up, but a key factor was the high price of oil in recent years - between roughly 2011 and 2014 the average price of a barrel was $100 or more.

"That period of time [when prices were high] allowed investments to be made in places such as very deep water in Brazil, Canadian sands and other parts of the world," explains Neil Atkinson, head of the International Energy Agency's oil industry and markets division.

In other words, the oil companies invested heavily in research and development at trickier sites, and in some cases are now benefiting from increased extraction.

An area long associated with oil production that some thought would have largely "dried up" by now is the North Sea, says Prof John Underhill at Heriot-Watt University in Edinburgh, Scotland.

"More oil is being produced from those depleted fields than ever was thought possible when the North Sea was opened up," he says.

One new approach he cites is directional drilling, in which non-vertical wells are bored into the oil field.

"One can target those pockets of oil that would otherwise be left behind," he explains.

There have been innovations in injection too - the process of putting fluid into an oil reservoir to increase the pressure, helping it to flow through to the well.

At BP's major new site at Clair Ridge, off the coast of Shetland, chemistry will be harnessed to dislodge oil from the reservoir during injection.

The technique involved is called "LoSal". The oil in the Clair field clings to clay thanks to ions - atoms or molecules with an electric charge. They act a bit like a chain holding the hydrocarbons in place.

However, by lowering the salt content of the water in the reservoir, BP thinks this will make the chemical bonds of that chain relax.

If that happens, the ions may be replaced by less binding ones, releasing the hydrocarbons in the process. BP plans to begin production at Clair Ridge in 2018, and continue recovering oil from the field for the following 32 years.

The list of options for engineers vying to lure yet more oil from underground reservoirs is certainly growing.

Some firms, like Titan Oil Recovery in the US, are even enlisting the help of microbes, tiny organisms living within the oil field.

A sample of water in the field is sent to the lab for analysis, explains chairman and founder Ken Gerbino.

The goal is to find a microbe living there that can be fed and encouraged to proliferate. Once one is identified, Titan can deliver its - secret - formula.

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"They multiply like crazy," says Mr Gerbino. The microbes, booming in number, surround globules of oil trapped in the porous rock.

"They physically deform the droplets into micro oil droplets," he explains. That means that the oil is more mobile and easier to recover.

"We've been on 48 commercial oil fields, we've done over 300 well applications, and the average increase in production has been 92%," he adds.

But microbial enhanced oil recovery, or MEOR as it is known, is not commonplace despite having been in development for many decades.

MrGerbino says his company's approach can cost as little as $6 per barrel, but the oil industry has long hesitated over MEOR techniques because of high costs and fears that microbial manipulation might not work as intended.

Of course, specialised techniques for encouraging oil towards the production well are one thing - simply locating pockets of oil suitable for extraction is another. This is no mean feat when, as in the North Sea, hundreds of smaller pools of oil are of course locked under the seafloor. Selecting which to aim for needs to be done carefully.

But augmented reality could soon help engineers decide which of these resources to earmark, according to Chris Pearson, small pools solution centre manager at the UK's recently opened Oil and Gas Technology Centre (OGTC),

The OGTC is working with Aberdeen University to develop 3D visual representations of reservoirs - simulations of the oil field - based on data from geophysical surveys.

Artificial intelligence techniques can then predict what oil in that model is most recoverable and these evaluations can be represented within the 3D view.

"I'd call it augmented decision-making," says Pearson. "It gives you a more informed view of what the reservoir looks like."

For those in the oil industry right now, new technologies are just part of the excitement associated with high levels of both supply and demand.

They also play to many people's confidence that "peak oil" - when the maximum rate of oil extraction has been reached - is still a long way off.

And that, of course, is despite continued concerns that the fervour to extract more oil will lead to serious environmental problems - including, ultimately, a problematic contribution to climate change once those hydrocarbons are burned as fuel and emissions released.

But peak oil has certainly seemed more distant in recent times than it did, say, 10 years ago. The entrepreneurs and engineers behind new extraction technologies have plenty of faith that the status quo will continue - as does Neil Atkinson at the IEA.

"Oil production has been going up and up and up remorselessly for a very long time," he says, "and it will continue to do so."