New gas and water technologies could add decades to the lifespan of oil reserves in the North Sea, according to Edinburgh researchers.
A Heriot-Watt University team said they had made a breakthrough in developing clean and cheap methods to maximise extraction from existing fields.
The university has been working on a technique known as low-salinity water injection.
The team has been researching which fields would benefit most from it.
Researchers have also been developing gas injection technologies for use in reservoirs that are already flooded with water.
Professor Mehran Sohrabi, director of the university's centre for enhanced oil recovery, believes new technologies could be a game changer for the industry and has called for more investment to reverse the decline in North Sea production.
He said: "At least half of the original oil still remains in the North Sea reservoirs but there are great challenges in extracting it using enhanced oil recovery (EOR) techniques.
"These include limited platform space and large well spacing, making extraction too expensive to pursue.
"Following years of research at the university, we now believe we can overcome these challenges."
Low-salinity water injection works by reducing the salt levels in sea water that is already injected into reservoirs.
Mr Sohrabi said: "It has the potential to make a huge impact on the current output of the North Sea's oil production.
"We have developed a robust method to screen oil reservoirs to identify the ones that would respond positively to low salinity water injection.
"This allows us to estimate the size of incremental oil recovery, which is vital for economic calculations of enhanced oil recovery projects."