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BG and Petrobras sponsor research to boost recoverable oil in limestone reservoirs

20th February 2015

The amount of oil recoverable from reservoirs in deep rock formations could be improved, following a new discovery by scientists at the University of Edinburgh and Heriot-Watt

The amount of oil recoverable from reservoirs in deep rock formations could be improved, following a new discovery by scientists at the University of Edinburgh and Heriot-Watt
Droplet fragmentation visualised in 3D using x-ray microtomography. In (A) a droplet of oil (red) is suspended and trapped in a pore surrounded by brine (blue). Fast injection of the brine fragments the trapped droplet into hundreds of smaller droplets (B) enabling production of a proportion of the trapped oil. Source: BG Group

The research, published in Proceedings of the National Academy of Sciences, was carried out by scientists and engineers as part of the International Centre for Carbonate Reservoirs (ICCR) programme which is sponsored by Petrobras and BG Group.

Researchers have identified a naturally occurring characteristic of oil that could be exploited to help improve its recovery from the subsurface.

Approximately half of the world’s remaining oil reserves are held in limestone reservoirs. Scientists have been using sophisticated X-ray technology to examine in three dimensions exactly how oil and other liquids flow within limestones.

Researchers found that in the complex pore structure of limestone, a previously unrecognised process allows oil droplets that are trapped in large pores to be broken up into smaller fragments by flowing water, allowing them to move more easily through the pore network.

Researchers say the findings could be applied to boost the yield from oil reservoirs by a few percent which could account for significant volumes in the case of large reservoirs. This may be important for the recently discovered giant pre-salt carbonate oil fields in Brazil, which have very complex and multi-scale reservoir pore systems.

The phenomenon may also have applications in treating contamination in natural aquifers, which contain more than half of the world’s groundwater resources.

It could also help develop techniques for use in carbon capture and storage, a technology that buries carbon dioxide emissions in former oil and gas fields, preventing the release of greenhouse gases to atmosphere.

Tannaz Pak, formerly of the University of Edinburgh’s School of GeoSciences, who took part in the study, said: “Thanks to new technology, we can see in detail how the fluids move within the rocks. Our new findings shed light on a natural process occurring in oil reservoirs and contaminated aquifers, and during carbon capture and storage. It could prove valuable in both oil recovery and environmental applications.”

For the sponsors, another successful aspect of this research, in addition to the novel results, was the extensive knowledge interchange and technology sharing with Brazilian universities.

BG Group and Petrobras have just kicked-off the ICCR phase II programme of exciting new research projects and are looking forward to being engaged with further high-end research of this quality.

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