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From acorns to oaks

Written by  Emma Gordon Sunday, 01 October 2017 00:00

With oil prices expected to remain low, decarbonization targets looming and infrastructure nearing the end of its life, is it time for the North Sea industry to start taking carbon capture and storage seriously? Emma Gordon reports from SPE Offshore Europe.

The energy industry needs to be ambitious when it comes to carbon capture and storage (CCS), according to Stuart Haszeldine OBE, director of research group Scottish Carbon Capture and Storage (SCCS).

Following the lead of Norway, which began storing CO2 beneath the North Sea more than 20 years ago, with the Sleipner project, could, Haszeldine believes, position Scotland and the UK as a provider of CO2 storage for the domestic market as well as mainland Europe: in effect creating an industry that could last for “100 years or more, and provide an environmental service.”

Speaking at SCCS’ “North Sea CCS: innovation and impact” event during SPE Offshore Europe last month, Haszeldine, who is also professor of CCS at the University of Edinburgh, says the industry must start to “transition to … a new way of using our skills and assets in the North Sea, because it’s clear the oil price is low, the price of oil is likely to remain low. It’s also clear the North Sea is more than half way through commercial production of oil. The industry really needs to think about what comes next.”

Those who promote CCS argue that even with the adoption of renewable technologies, the demand for energy and the ongoing need for fossil fuels in some industries, and not just power production, means that, to meet climate change targets, CCS is still needed.

Norway’s Sleipner — and the later Snøhvit project — have together collectively stored more than 21 million tonnes of CO2, showing that CCS in the North Sea is technically feasible, Statoil’s Bamshad Nazarian told Offshore Europe. Gassnova, the Norwegian state enterprise for carbon capture and storage, has assigned Statoil to evaluate the development of carbon storage on the Norwegian continental shelf (NCS) as part of plans to develop a full value chain by 2022 (Read: Creating a carbon store).

While Norway’s efforts have been lauded in the UK, SCCS says that the UK needs to up its game. If it doesn’t develop its own industry, the UK might have to “outsource” its CCS industry, i.e. pay Norway to collect and store UK.

Support for CCS technology development in the UK has, however, been limited. In 2015, the UK withdrew committed funds from a CCS competition for a full-scale project just before finalizing the front-end engineering phase for two projects.

The CCS cycle. Image from CO2Deepstore.

Acorn

All is not yet lost for the UK, however. A feasibility study for the Acorn Carbon Capture and Storage Project in Scotland started in September, supported by EU and Scottish Government funding.

With a potential go-live date of 2022, the project centers on the northeast of the country where it’s proposed CO2 would be captured from existing emissions at the St Fergus Gas Terminal. The CO2 would then be transported offshore and injected underground for storage. Two sites are under consideration, including the Captain formation.

Acorn. Original image from Pale Blue Dot Energy. 

It’s proposed that Acorn would reuse the existing oil and gas infrastructure — with three pipelines, the Atlantic/Cromarty (WAGES); Goldeneye and Miller pipelines considered potentially suitable for transporting CO2. On its current timetable the project could be operational before 2022, and is planning to capture about 200,000T/y of CO2 in Phase 1.

Alan James, managing director of Pale Blue Dot Energy, a firm leading the project that was developed by CO2DeepStore, told SPE Offshore Europe: “We wanted to find the smallest, industrially-viable project to minimize capital expenditure to start with. Earlier projects had fallen over because of cost or issues around government spend. The key thing is to build on what’s already been done. All that has been done so far is an essential foundation for going forward.”

He adds that Acorn could ultimately act as a hub for a growing number of projects including the Grangemouth Industrial Cluster, the Teeside Collective, and CO2 Sapling: a transportation infrastructure project. It could also grow by adding CO2 from other local sources, from industrial and power sources in central Scotland transported via existing pipelines and by importing CO2 by ship via Peterhead Harbour.

Acorn research and academic partners include SCCS, Bellona, the University of Liverpool, and Radboud University in Nijmegen; Guangdong CCUS Center, Massachusetts Institute of Technology, Costain, and Summit Power are among the collaboration partners.

However, there is a race against time for UK North Sea CCS to begin in earnest before crucial infrastructure, such as the three pipelines being considered for the Acorn project, are decommissioned, Haszeldine says.

Haszeldine says that the capital expenditure of a newbuild pipeline system would be more than US$136 million (£101 million); while repurposing the existing system would be around $44 million (£33 million): a saving of about $92 million (£68 million).

And, there is added impetus for the industry in the context of the Paris Agreement, for example. Haszeldine says that it will become clear to all industrial countries over the next few years that they are “nowhere near decarbonizing and storing enough carbon to meet their commitments. I’m hopeful that within the next 5-10 years, storage of CO2 will become a requirement rather than an interesting side event.”

Considering CO2 for EOR

With an estimated potential of 5700 MMstb, CO2 EOR has the highest potential of all EOR techniques to maximize recovery from depleted UK oil fields, says Jamie Stewart from the University of Edinburgh.

Yet, even though the approach has been used since the 1970s, so far, the technique has not been used in the North Sea.

Stewart told SPE Offshore Europe that the process sees CO2 injected into depleted reservoirs to increase pressure and reduce oil viscosity, with the “aim of the game to drive oil stuck in the field towards a production well… with some stored in the reservoir.”

In North America, there are more than 120 projects injecting around 40-tonne of CO2 a year, with the majority, some 65, in Texas.

While these projects in the US have primarily focused on oil recovery and not storage, CO2 EOR is increasingly being considered as a storage option, Stewart says.

CO2 EOR has been held back in the North Sea due to lack of supply, he says. “We don’t have access to the volumes of CO2 required, low cost options for purchasing, and a fairly big investment is required for some of these projects,” he says. “There is lots of competition from other types of EOR… and some of these other technologies have a lower cost, such as [lower salinity waterflood].”

University of Edinburgh research has looked at CO2 EOR potential in residual oil zones (ROZ), where hydrodynamic tilting of the oil water contact has naturally occurred, leaving a zone of oil.

This work looked at Shell’s Pierce field — 265km (165mi) east of Aberdeen — where, Stewart says, recoverable reserves from the ROZ may approach 20% of the total field recoverable reserves. He added that the field could also have the capability to store up to 17-tonne of CO2.

“CO2 EOR has a potential to produce relatively low carbon intensity oil from a mature basin… it’s exciting that it has the has the potential to offset new exploration… and if we can focus our attention on mature fields in the North Sea, I think that’s a good way to go.

“[We have] also shown there might be more potential than is currently recognized from standard CO2 EOR in these ROZs. Obviously, lots of barriers still exist, and getting projects off the ground, and getting volumes of CO2 needed… will be difficult, but it is something that I think makes sense in the North Sea,” he says. 

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Creating a carbon store

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