Oil recovery in reverse

samle-ingress
12.06.2014
The world is on the hunt for opportunities to get rid of the problematic CO2 gas. The Norwegian Petroleum Directorate (NPD) has shown it is possible to store vast volumes on the Norwegian shelf.

However, as long as it is illegal to import CO2 for this purpose, we are exporting knowledge on how it can be done.

Since 2011, the NPD has published CO2 atlases for the Norwegian part of the North Sea, the Norwegian Sea and the Barents Sea. We have also published an updated general atlas of storage sites, providing, among other things, an in-depth description of the method behind the work.

In order for global warming to be limited to two degrees, approximately 120 billion tonnes of CO2 must be captured and stored between 2015 and 2050, according to the International Energy Agency (IEA). More than 3000 capture and storage plants must be operational by then, according to the Agency. As of last year, there were eight.

The NPD’s atlas shows it is theoretically possible to store 80 billion tonnes of CO2 on the shelf. In other words, Norway has storage space in spades, while our total annual emissions are about 50 million tonnes. In comparison, one single German coal power plant – Jänschwalde in Brandenburg – emits about half this much over the course of a year.


High-demand knowledge

The Norwegian Petroleum Directorate did not invent the wheel. Other countries have carried out similar tests and prepared maps of possible storage sites, mainly on land. However, no one else has access to such an extensive data basis; detailed information on reservoirs, drilling operations and wells, collected by the companies that have conducted oil and gas activities in Norway for nearly 50 years. This data, preserved and systematised by the NPD, has enabled us to fulfil the assignment given to us by the Ministry of Petroleum and Energy five years ago; to map possible offshore CO2 storage sites. This, and the geological expertise in our organisation which has carried out multiple analyses and reservoir simulations in the effort to produce the atlases.

We have mapped formations filled with seawater and other “pockets” in the subsurface on the shelf, including decommissioned oil and gas fields. When evaluating whether these structures are suitable for storage, we have used our extensive knowledge of reservoir properties, sealing rocks, migration paths, storage capacity and monitoring methods.

In many ways, CO2 storage is like oil recovery in reverse. The same geological structures that have held oil and gas for millions of years should be able to receive and hold CO2 injected from above. The most important criterion is that these storage sites are sealed, so the CO2 will not leak out in the future.

One of the reasons for initiating the work on the maps was the ongoing process in the EU to find out how much CO2 could be stored in the member countries. The EU assumed then that 25 per cent of the gas could be stored in the Norwegian part of the North Sea. Together with the need to achieve our own goals for lower greenhouse gas emissions, this sped up the Norwegian authorities’ work on mapping the storage opportunities off the Norwegian coast. This could be interesting for countries with major CO2 emissions.


Obstacles
Transporting CO2 across international borders is not currently permitted, because CO2 is defined as waste in international regulations. However, small volumes of CO2 are already being transported by ship for commercial use in e.g. the agricultural sector and brewery industry. In such cases, CO2 is defined as a commodity, and is therefore legal to transport between countries.

Though more knowledge and technological solutions are still needed in order to store vast volumes of CO2, the challenges are primarily of a regulatory nature. And, not least, finding a business model that makes CO2 storage attractive. For example, by injecting CO2 to increase oil recovery from fields, or because it will become so expensive to emit CO2, that the profitability of storing it exceeds the costs.

Until regulations and business opportunities are in place, the NPD is exporting knowledge to the rest of the world. Research communities, educational institutions and authorities in countries across the world are in contact requesting atlases, and to learn about mapping and qualification of CO2 storage sites.

We have also received several requests for information from national oil companies in Asia, because the petroleum reservoirs in this region have a very high percentage of CO2. There are gas reservoirs off the coast of Vietnam with such significant CO2 content that they cannot be produced, and the gas in the enormous Natuna field off the coast of Indonesia contains 70 per cent CO2. In comparison, the gas from the Sleipner area in the North Sea – where Statoil has injected about one million tonnes of CO2 each year since 1996 – contains about 10 per cent.

On the Norwegian shelf, CO2 is currently separated out on the Sleipner West, Snøhvit and Gudrun fields and stored in water-filled geological formations. In the future, it may become necessary to do this on more fields, and the NPD has mapped structures that could be suitable for this purpose.

Time will tell whether the Norwegian shelf can also contribute to help the UN and politicians achieve their goals.

 

Director General Bente Nyland is one of Stavanger Aftenblad’s (regional newspaper) regular energy commentators. This comment was published in the paper edition and Aftenbladet’s website on Thursday, 5 June.