Drill tool could enhance oil recovery from existing wells
12 May 2013
A novel oil drilling tool, currently under development at SINTEF Petroleum Research in Norway, has characteristics that will enable it to take on a number of different tasks.
One of these is to recover oil from small oil-filled pockets that lie close to large fields on the continental shelf. While a single pocket might be considered insignificant in terms of its reserves, when taken together they represent a significant new resource.
SINTEF’s new ‘mole’ has an extra set of ‘teeth’ along the side of the tool - a conventional design has all the cutting equipment at the business end of the design. The equipment is still on the drawing board, but the researchers have been using a 12 metre-long model of an oil-well to show how it will work by recreating the imprints – essentially spiral grooves - that these extra teeth (or side-cutters) will leave in the wall of a real oil well borehole. The grooves so formed have a very important role to play; tests on the well model have shown that the grooves improve the efficiency of removal of drill cuttings.
The oil-bearing strata on the Norwegian shelf probably contain many thousands of small oil-filled pockets, and reservoir experts believe that there is just as much oil left out there as has been so far produced from all the major discovered fields put together. Drill tool project manager, Jan David Ytrehus takes up the story:
“We believe that the new tool will make it easier to drill branches from existing wells out to nearby pockets of oil. If we explore and drill in the traditional manner, many small reservoirs will remain unprofitable and undisturbed. But if we can drill across to some more of them from existing wells, costs will be significantly reduced, and such ‘dwarf’ reservoirs close to the giants will become worth exploiting. This will be a very efficient way of enhancing oil recovery rates.”
One of Norway’s experts in petroleum research who is very interested in small unexploited reservoirs is Hans Borge, who directs the Department of Petroleum Technology at the University of Stavanger. Borge believes that the Norwegian continental shelf houses anywhere between 1,000 and 10,000 pockets of untapped hydrocarbons.
According to Borge, the greatest challenge lies in knowing exactly where these small deposits are to be found. He also points out that combined exploration and production wells are likely to be a sensible strategy for Norway to adopt in the hunt for these pockets.
“Suppose that there are 10,000 such pockets,” he suggests.
“If we conservatively assume a price of US$ 60 per barrel, these contain oil worth NOK 20 000 billion. Now that would be come to several sovereign wealth funds! But using traditional technology, it would easily need NOK 20 000 billion to produce that oil. And that is simply not realistic.”
Borge estimates that one per cent of the pockets lie less than one kilometre from a reservoir from which hydrocarbons are already being produced. “A single percentage may not sound like much,” he says, “but there is good reason to believe that in that one per cent of pockets lies oil worth several hundred billion Norwegian krone. And no matter which Norwegian oil-field you are on, there will always be small unexploited reservoirs in the vicinity.”
If the new drilling tool meets the expectations raised by the laboratory results, Ytrehus believes that it would be possible to drill out to pockets up to a kilometre from current wells, if not further. But why should this new drilling tool be able to drill its way onwards from existing wells? And why is it difficult to do this using traditional equipment?
Project manager Jan David Ytrehus is keeping his cards close to his chest but says the new tool has already been enthusiastically received by both the offshore and its allied service industries. SINTEF’s next step is to commercialise the new system and will be establishing a company for this purpose.
SINTEF is the largest independent research organisation in Scandinavia