Past, present and future use of geophysics at the NCS Adriana Citlali Ramirez under her keynote presentation at the conference. Photo: Terje Solbakk.

Past, present and future use of geophysics at the NCS

"When it comes to geophysical data surveying in the NCS, we are very spoiled right now, we have access to all the options and knowledge that were just dreams a few decades ago."

“Ideas tend to be old», Adriana Citlali Ramirez from TGS told the audience at the NPF Biannual Geophysical Seminar at Fornebu, Oslo, on March 10.

“In the last decade, we have managed risks to accelerate the large-scale utilization of old ideas, further enhancing them and establishing them as new standards”.

“This is especially true for technologies whose success depend on a combined development of acquisition and processing technology, such as the case of broadband and multi-sourcing,” Ramirez continued.

Her keynote presentation was themed around the fluctuation of the oil price, from the first price boom back in the 1800s when kerosene was introduced for home lighting, to the ups and downs until the present day, accompanied by the implementation of large advances in geophysical imaging.

The oil price graph converted to 2014 USD from 1959, when the North Sea area became focus for hydrocarbon exploration, until early 2020. Technologies shown are not necessarily first used in the North Sea. Figure: Adriana Citlali Ramirez, TGS.

One of Ramirez’ slides focused on the last 60 years on the Norwegian Continental Shelf (NCS, figure), with the introduction on different technologies for both exploration and reservoir monitoring together with the oil price.

On the NCS, following the discovery of the Ekofisk field (1969), and the field development together with more discoveries, was accompanied by advances in offshore geophysical data acquisition and later reservoir monitoring.

Examples include the first 3D seismic streamer in 1974, the OBS (ocean bottom seismic) over the Tommeliten field in 1993, the 2003 Life of Field Seismic (LoFS) being installed on the Valhall field, and in 2019 the large Utsira dense OBN (ocean bottom node) MC survey.

The North Sea area with fields mentioned in the oil price figure from TGS.
Map: norskpetroleum.no

Things change, OBS surveying is an example where the costs limited negatively its large-scale utilization. For decades, surveys only covered areas smaller than 200 km2 and OBS were primarily used for production monitoring, according to Ramirez.

In the last two years, both technological improvements and new business models in the OBS (Ocean Bottom Survey) market, such as Multi-Client, have lowered the prices and made it attractive for exploration at unseen scales. One example of this is the new Utsira OBN from TGS that covers more than 1500 km2.

“You need to match what data you need to the problem you are addressing.”

In the mature areas, we need new commercially viable discoveries that can be tied into the existing infrastructure to ensure the continuation of the ongoing production.

Here, Ramirez points out that we need to find what we haven’t found yet with all the existing data. Maybe it is time to get the data with the least compromises (full azimuth, high fold, long offset OBN) and fully exploit it.

In the more frontier areas, Ramirez reminded us that there are plenty of remaining challenges: from how to overcome multiples and common illumination problems, to dealing with complex geology such as sills, basalts, and salt.

“We cannot expect a huge discovery if we do not take any risks and don’t do the necessary work. We need to really commit to exploring these areas and deal with the challenges matching them to the right technology,”

The Norwegian Petroleum Directorate estimates that 48 per cent of resources in Norwegian waters are undiscovered, most of these resources are expected in underexplored areas where one may encounter such problems.

TERJE SOLBAKK

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