Simple tweaks to oilfield practice could provide the offshore industry with a more sustainable, money-saving solution to health and safety, environmental and commercial threats posed by harmful bacteria in subsea oil deposits.
According to experts at Newcastle University, easy-to-implement, cost-cutting measures – such as adjusting the water temperature used during oil production – could offer a way of tackling problems linked to sulphate-reducing bacteria (SRB) that is greener and more effective than those currently relied on.
SRB ‘breathe’ sulphates but exhale toxic, corrosive hydrogen sulphide (H2S).
The Engineering and Physical Sciences Research Council (EPSRC) is funding the near-£1 million deep bio-engineering research project, which is led by Newcastle University. The work involves a range of private sector, public sector and academic partners from the UK and overseas.
First evolving billions of years ago, SRB thrive in oxygen-free, watery environments like those that can be found in offshore oil deposits. The H2S they produce, however, is a key cause of ‘reservoir souring’, increasing the oil’s sulphur content and so reducing its market value.
H2S is also highly toxic, posing a potentially deadly hazard to workers on offshore platforms, while its corrosiveness can damage pipelines and rigs, leading to oil leaks and spills.
As part of its work to understand how SRB – some of which can lie dormant for very long periods – become activated in oil reservoirs, the Newcastle-led team is investigating the widespread practice of pumping seawater into an oil reservoir to reduce temperatures and make extraction easier but which poses problems from a reservoir souring perspective.
Dr Casey Hubert of Canada’s University of Calgary, who is leading the research in his role as Visiting Professor at Newcastle University, explained: ““Seawater is rich in sulphates, which SRB use for their metabolism.
“Our results suggest that warming the injected seawater, so that the temperatures in a hot reservoir drop down to say 70°C rather than 50°C, could prevent SRB activity without significantly affecting the oil extraction process.
“Our overall aim is to identify ways of making oil recovery more environmentally friendly. If we end up continuing to rely on fossil fuels for a few more years or decades then the imperative must be to meet our energy needs efficiently and with minimum impact on the environment.”