Rock-solid resource

26.06.2013
A total of 6.6 kilometres of shallow stratigraphic cores from the NCS are stored behind walls more than three metres thick in a former submarine pen in Trondheim. The NPD took over this facility in February.
  • Bente Bergøy and Emile Ashley (photos)

Atle Mørk (left) at Sintef Petroleumsforskning and professor Mai Britt Mørk (right) at the department of geology and mineral resources engineering. Behind them are students (from left) Kristoffer Solvi, Ane Andrea Svinth, Turid Haugen, Even Nikolaisen and Gareth Lord.

Studies.
The core store and display room are much used by NTNU students, according to senior research Atle Mørk (left) at Sintef Petroleumsforskning and professor Mai Britt Mørk (right) at the department of geology and mineral resources engineering. Behind them are students (from left) Kristoffer Solvi, Ane Andrea Svinth, Turid Haugen, Even Nikolaisen and Gareth Lord.

 

Ownership of the store was acquired from the Sintef research foundation after it had been managed for many years by the museum at the Norwegian University of Science and Technology (NTNU).

“We have an overall responsibility for administering geological materials from the NCS,” observes NPD director general Bente Nyland.

“We also make provision for scientists, students and oil companies to study these resources. So we’re very pleased to have secured this collection.”

The cores were obtained from shallow wells drilled in 1982- 93 by the former Continental Shelf Institute (IKU) – now Sintef Petroleumsforskning AS.

During the period, one-three expeditions were staged annually with drill ships. Parts of the NCS were mapped using shallow high-resolution seismic surveys and stratigraphic drilling. Most of the wells were drilled in the Norwegian and Barents Seas.

The NPD’s rock store in Stavanger contains cores and drill cuttings from virtually all the exploration and production wells drilled on the NCS.

But most of the cores hail from reservoir rocks. Geologists would prefer many metres of cores from a well rather than simply cuttings, but that would be too expensive. Each metre of core drilling can cost several hundred thousand kroner.

“We drilled full cores from the seabed through both source and reservoir rocks,” explains senior researcher Atle Mørk at Sintef Petroleumsforskning. “So they provide useful information on the sub-surface.”

This work was funded by a number of oil companies through various projects, and the collection comprises cores from more than 90 wells on the NCS.

The latter were drilled in waters depths of 100-1 500 metres, with the shallowest driven only a few metres into the seabed and the deepest going down to almost 600 metres.

While each expedition as such cost roughly NOK 20 million, the total bill – including processing – came to almost NOK 500 million.

Drilling locations were determined on the basis of detailed seismic surveying, and analysing the samples yielded very useful information.

“We chose sites where interesting strata were not far beneath the seabed, and where they could be followed down to deeper structures of interest for oil exploration,” explains Mørk.

In the modern display room at the Trondheim facility, core sections cast in epoxy are presented from virtually all the stratigraphic cores collected.

The remainder of the cores from each well are held in the storage area, neatly organised in boxes.

“We began with ordinary bits until we reached the bedrock, and then continued with diamond bits,” says Mørk. “We brought up three metres of core each time we retrieved the bit to the drill floor.”

He knows more than most about the cores in the IKU collection. Not only was he involved in the bulk of the drilling expeditions, but also analysed the samples afterwards.

Results from this drilling and the subsequent work have been documented in a number of reports and publications. And the material remains relevant.

The geological samples from the shallow wells are used in research and teaching – primarily in connection with courses, projects and MSc theses at the NTNU.

Measuring five-seven centimetres in diameter, the cores have been split vertically and provide a quick overview of rock types and sedimentary structures.

They can be used for research in a number of areas, such as sediment types, stratigraphy, deposition environments and climate variations.

The age of the samples ranges from the Ordovician period about 450 million years ago to the late Cenozoic era as recently as 2.5 million years ago.

“We make much use of the core store and the display room,” reports professor Mai Britt Mørk at the NTNU’s department for geology and mineral resources engineering.

“We’ve run a series of courses in sedimentology for geology students, for example, and a number of students have drawn on the cores in their MSc theses.”

Oil companies also study the material in connection with exploring the NCS and hunting for petroleum. It was extensively used, for instance, by companies preparing applications in the latest 22nd licensing round on the NCS.

Plans call for the cores to remain at the Trondheim store, and an agreement has been reached between the NPD and Sintef Petroleumsforskning on sharing lease costs for a decade with options for extensions.

As the main user for courses and student work, the NTNU will be responsible for practical operation of the store.

 

Limestone containing many mussel fragments and the cross-section of a belemnite, a fossil squid

Squid.
Limestone containing many mussel fragments and
the cross-section of a belemnite, a fossil squid.

 

Even Nikolaisen and Turid Haugen study display sections

Sections.
Even Nikolaisen and Turid Haugen study display sections.

 

Cores

Cores.
Sections cast in epoxy from virtually all the stratigraphic cores
collected are presented in the display room.