By Dorte Larsen, Communications Specialist, AAU Communication and Public Affairs
Photo: Shutterstock, Alessandro Perrucci and Marzia Anna Stramaglia

At Aalborg University, researchers are making progress on developing a more sustainable solution that aims to significantly reduce the amount of chemicals used in oil and gas extraction in the North Sea. Currently, a major innovation project, INNO-H2S, is creating new technology to recover large quantities of unspent MEA-triazine that would otherwise be discharged into the sea. This new technology will significantly reduce the environmental impact factor (EIF) for a range of installations in the North Sea.

The problem with hydrogen sulfide

Hydrogen sulfide (H2S) is an extremely toxic and potentially corrosive substance found in the mixture of gas, oil, and water extracted from underground during oil and natural gas production. H2S must be removed before the gas is piped to export to comply with health and safety regulations. 

Chemicals can remove hydrogen sulfide from gas streams

In offshore oil and gas production, the problem of hydrogen sulfide is addressed by injecting chemicals – H2S scavengers – during the extraction process. In addition, after the gas is separated from oil and water, H2S scavengers are directly injected into the gas stream to ensure the gas meets the export specifications. The most used H2S scavenger is MEA-triazine. To illustrate the scale of the operation, several tons per day of MEA-triazine are used at multiple North Sea installations.

While this process is beneficial for asset integrity and safety, it is not without its downsides. Project leader Marco Maschietti explains:

“The biggest drawback is that this process needs to be run with excessive MEA-triazine, to ensure H2S is safely removed. Consequently, the wastewater produced in the process, the so-called “spent H2S scavengers”, ends up containing large amounts of unspent MEA-triazine besides the scavenging reaction products. There are often no feasible solutions for on-site treatment or disposal of this wastewater. Therefore, in these cases, this wastewater is routed back into the systems and discharged.”

Recovering and reusing MEA-triazine

Now, a grant from the Danish Energy Agency’s EUDP program supports the development and demonstration of a solution to recover unused MEA-triazine from spent scavengers. The recovered MEA-triazine will be re-used in the process for the removal of H2S. The project aims to cut MEA-triazine consumption and its discharge into the sea by 34–68%, depending on the installation. If successful, the new technology will lead to significant reduction of EIF and operational costs for Oil and Gas operators, as well as a reduction in the amount of chemicals to be transported to offshore installations, thereby also reducing CO2 emissions. 

From lab scale to large scale

The technology used in the INNO-H2S project is based on membrane nanofiltration. The technology has already been proven and successfully tested at lab scale at Aalborg University in a previous research project funded by DTU Offshore. 

In the INNO-H2S project, the technology will first be tested on a larger scale on a pilot unit developed at Aalborg University, equipped with industrial membrane modules. In this first phase, researchers will focus on optimization of the process and long-term operation.

If the first phase is successful, the project will continue to its second phase. Here, the first two membrane recovery units will be implemented on offshore installations operated by TotalEnergies and OKEA in the North Sea. The project consortium also involves SLB (a global energy technology company), MMS Nordic (a Danish membrane systems company), and DTU Offshore.

Solutions for the world’s oil and gas production

Considering the climate crisis and the green transition, most countries are working to shift away from fossil fuels and toward renewable energy sources. Therefore, it may seem paradoxical that Denmark, as a society, continues to develop solutions for the oil and gas industry.

“Even though many countries are aiming at transitioning to renewable energy, which is very much needed, oil and gas will still play a role in the global energy mix for years to come. In addition, besides energy, oil and gas contribute key chemicals, materials, and products that we use every day. This is why we must continue to focus on innovating the way oil and gas are produced with a clear aim of reducing the environmental footprint. By developing cleaner and more efficient technologies, we can minimize the impact to ecosystems while also creating export opportunities for Danish innovation in Denmark and abroad,” Marco Maschietti ends.