After more than 40 years of production in the North Sea, with declining production and an ever more complex and costly operating environment, it could be easy to view the basin with a “glass half empty” attitude.
However, the industry and authorities are taking the opposite view—but with their eyes wide open.
The UK Continental Shelf has so far produced just over 41billion boe. The recovery rate is an average of 40% and is on track to be 46%, says Ian Walker, of ConocoPhillips but who was on secondment to the Department of Energy and Climate Change (DECC).
“With a global average of 30% it could be easy to say it is expensive to go further in the offshore environment with high well costs,” he said. “We have done a good job using water flood, it went in when it was required. But at the same time, it is asked why are we leaving so much behind? There is more that can be done in EOR (enhanced oil recovery).”
But, he warned the recent DEXEX 2013 conference in Aberdeen last week (May 15/16), the industry is running out of time, with production declining (at 1.5mm boe/d in 2012), threatening the life of “core pieces of infrastructure”.
In a joint effort to speed up the development and adoption of EOR technologies in the UKCS, DECC with industry has an EOR work group which carried out a screening process of North Sea fields to see what technologies could most effectively be applied (and where) and what the prize could be.
Technologies looked at were miscible hydrocarbon flood, nitrogen and flue gas, miscible CO2, surfactant/polymer, polymer, in situ combustion, steam drive, bright water (“strong gel”), low salinity and CDG (colloid dispersal gel/”weak gel”).
“When you look at it and look at the geographies technologies might apply to, there are a few technologies that come to the fore,” says Walker. These were miscible hydrocarbon flood, miscible CO2, surfactant/polymer, polymer and low salinity.
“Low salinity (water) lends itself to early adoption, chemical EOR would come a bit later because it is less easy to implement, and miscible gas would be later too,” he said. “But in the North Sea there are examples of all these technologies at work.”
There were three areas deemed optimal as EOR candidates, with cluster areas identified. These were around Taqa Bratani’s northern North Sea assets, the central North Sea near BP assets and around Nexen’s assets in the Moray Firth. Work to progress their suitability is now getting under way.
The research so far, despite being “a bit course”, showed the prize could be 6billion bbls, says Walker, a significant sum when the estimated remaining recoverable resource has been put at 10-20billion bbls.
As part of the work, industry workshops have been held with 12 operators, with an appetite for low salinity technology being seen, says Walker. However, there are still uncertainties and a need to share information, provide guidelines and encourage co-operation.
“It is low cost and there is scope for standardization and scope for shared projects,” he says. “But there is also nervousness.”
Detailed work has unearthed a feeling the chemistry involved isn’t really understood and that the results are not really under, an issue not helped by mixed core results to date, potentially unnerving investors.
Recommendations by the work group have sought to address this. Core testing guidelines are being developed and participants are being encouraged to share data. There is also work to look at joint facility cluster areas.
“Creating a common core flood protocol and building a larger database of results would help tie down screening parameters,” says Walker. “Sharing lab results within clusters would encourage other operators.”
One operator involved in the work to date is Taqa Bratani. Peter Brand, asset development manager, at Taqa, said: “There is a need for speed if we are going to get anything done using these technologies, which is why sharing information, which is not a habit in the past, is going to be key to faster progress in future.
“We have done core experiments in Pelican and Tern so far with low salinity flooding. The results have not been spectacular but we do feel it has potential.
He said it was considered that a green-field approach would be needed to “kick-start” implementation of low salinity EOR in the northern North Sea, offering lower costs and bringing the having the added benefit of avoiding scale and H2S, adding to the possibility of using it even when the increment production is fairly low.
Walker concludes: “A collaborative program is the way forward. We want to get a few people ahead of the game so it can tug us all along.”