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Heriot-Watt researchers hope to boost extraction with low salinity water injection

Published:  16 October, 2014

Researchers at the Heriot-Watt University believe that they could maximise the North Sea’s oil reserves with low-salinity water injection to cleanly and cheaply extract valuable remaining oil from existing fields.

The Centre for Enhanced Oil Recovery (EOR), within the Institute of Petroleum Engineering at Heriot-Watt, claims a “massive leap forward” for oil reservoirs in an offshore setting.

Although around half of the original oil still remains in the North Sea reservoirs, there are challenges to extracting it, using EOR, such as limited platform space and large well spacing, making extraction expensive.

The Centre has been researching low-salinity water injection, which it says could be an industry game-changer. The process is relatively inexpensive, so the costs for EOR could fall dramatically, while yields could rise. It is also cleaner as the need for potentially toxic chemicals is removed.

Professor Mehran Sohrabi, director of the Centre for Enhanced Oil Recovery (EOR)

explained: “This system works by reducing the salt levels in sea water which is already injected in reservoirs. 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 EOR projects.”

For reservoirs that have already been flooded with water, the EOR Centre at Heriot-Watt University has been working on developing improved gas injection technologies. In water flooded reservoirs, gas injection will recover the trapped oil more rapidly compared to low salinity water injection.

Professor Sohrabi added: “Gas injection is a robust process but it is difficult to simulate its performance accurately as it happens under a complex three-phase flow regime. We have developed an algorithm for accurate prediction of gas and water alternating gas injection performance in oil reservoirs.”

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