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Hjem » Prosjekter » NORCRUST
Prosjektleder

Jochen Manfred Knies

Forsker
Telefon: 73904116
E-post: jochen.knies@ngu.no

NORCRUST

Publisert: 16. juni 2017 | Sist endret: 27. juni 2018
Prøvetaking rundt en naturlig lekkasjesone nordvest for Svalbard.
NORCRUST – Norwegian margin fluid systems and methane derived carbonate crusts.

Prosjektet har som formål å studere naturlige lekkasjesoner i Norskehavet og Barentshavet med nye, innovative metoder. Ved å integrere geologisk og geokjemisk informasjon fra lekkasjesoner på havbunnen og underliggende reservoarer skal vi tidfeste når lekkasjene på havbunnen har skjedd, skille mellom grunn biogen og dyp termogen opprinnelse av hydrokarboner, og rekonstruere temperaturen hydrokarbonene er dannet under.

For å nå målet skal vi studere karbonatskorper som dannes under havbunnen i lekkasjesoner samt gassimpregnerte sedimenter, og prøveta gassen som observeres i vannkolonnen over lekkasjesoner. En video omkring en naturlig metanlekkasje nordvest av Svalbard viser prøvetaking på havbunnen (se videoen i høyre spalte). Målet er å få bedre kunnskap om hvordan hydrokarboner har blitt dannet, hvordan de har migrert og når de har nådd havbunnen. I NORCRUST skal vi kartlegge migrasjon og lekkasje av hydrokarboner og prøve å koble observasjonene sammen med underliggende reservoarer gjennom numerisk modellering av petroleumssystemer.

NORCRUST skal samarbeide med verdensledende forskningsinstitusjoner innenfor geokjemi av stabile isotoper, U-Th geokronologi, mineralogi og petrografi. Prosjektperioden går fra 2016 og ut 2020.

Prosjektet er ledet av Norges geologiske undersøkelse (NGU) og finansiert av Norges forskningsråds PETROMAKS 2-program. Partnere er «CAGE – Senter for arktisk gasshydrat, miljø og klima» ved Universitet i Tromsø, Migris AS, Statoil ASA, Lundin Norway AS og ENI Norge.

 

Norcrust-tokt med G.O Sars

G.O. Sars cruise "NGU PL-1710, logbook.

Day 6, 12.08.2017

Finally, after 5 quite successful days the drama started on the last day. The ROV was supposed to be launched at around midnight when the weather said STOP. Strong winds and >3 m high waves made the operation impossible. The ROV crew stopped the operation and we decided to leave the Hola area and steamed back home to Tromsø. The immediate reaction was disappointment, but we realized immediately that this was the right decision. We arrived in Tromsø at lunch time. Cleaning the lab (Figure 1), group photo (Figure 2), unloading equipment and samples kept us busy for the rest of the day. The cruise officially ended in the afternoon and I am grateful to the captain Hans Troland and his crew and the ROV crew with Stig Vågenes for a wonderful and intense week on G.O. Sars.

  Figure 1: Cleaning laboratories is part of the job!
Figure 2: Group photo with all scientists and the ROV crew on G.O. Sars 2017111 (NGU P1710)

Best wishes, Jochen

Day 5, 11.08.2017

On day 5 of our scientific program, we mapped a second canyon with the multibeam system mounted on ROV Ægir 6000. Also in this canyon we found evidence for lithified sandstones cropping out along the steep walls of the canyons. The sandstones were sampled in the first canyon and will be prepared for age determination in our laboratories. The canyon walls are plastered with bacterial mats, carbonates and a biological community known from other seep sites in the Arctic (Figure 1).

studied canyon.
Figure 1: Plastered walls with bacterial mats, carbonates, and tubeworms in the studied canyon.

Unfortunately, these steep walls were difficult to sample and only two push cores were retrieved. We focused the sampling program on easily accessible areas within the canyon and took a number of carbonate crust samples and push cores. The program in the study area was concluded by a shallow seismic (TOPAS) survey.

Now, we are heading north and will stop at the Hola seep site off the Vesterålen coast. There we will perform a detailed multibeam survey and try to get a free gas sample from the bubbling seabed. In the meantime, the discussion of how to proceed with the new push cores and what measurements will  be conducted in the future is on (Figure 2)!.

Figure 2: First sketch on the number of pushcores, responsibilities, and planned analyses. A lively discussion, I can tell you…

This is far from being easy and keeping the overview is apparently my most important job during these exciting days ().

Still in good mood and looking forward to be in Tromsø again on Saturday evening.

Day 4, 10.08.2017

The scientific program of Day 4 started early. Around 4 am the ROV was launched at a spectacular site with a large number of bacterial mats and carbonate crusts (Figure 1).

Figure 1: Bacterial mats and carbonate crusts at the seafloor in our study area.

We collected 9 push cores and several carbonate crusts in a basket that was placed at the seafloor in order to keep the ROV "at work" (Figure 2).

Figure 2: The ROV brings the push cores and crusts temporarily to a basket at the sea floor. Once filled up, it will be brought up to the ships deck.

Once the basket was full, it came on deck and the scientific party began (Figure 3).

Figure 3: The work starts when the basket is on deck.

The push cores are sampled for porewater to trace geochemical processes related to fluid flow processes. Samples are also taken for gas measurements to determine the amount and its sources. The response of the biological community on methane seepage will be analyzed by means of planktic and benthic foraminifera. All carbonate crusts samples were documented onboard, however, the analytical program starts when the samples are in our laboratories. We also tried the gravity coring system to study the longer geological history in the study area. Unfortunately, the seabed in this region is very heterogeneous and no soft sediments were founds. Although the core liner penetrated the sediment surface, only a few sandy-rich carbonate pieces were recovered.  Today will most likely be the last day of intense sampling. Tomorrow, we expect a storm in our study area after lunch and no more ROV work will be possible. Despite the long days, the group works very well together. 

Day 3, 09.08.2017

Figure 1: The high-resolution multibeam bathymetry from our Canyon.

On Day 3, we finished the multibeam bathymetric survey of the ROV (Figure 1). The new map revealed interesting features beyond the presence of carbonate crusts, tube worms, and bacterial mats. Our first tentative interpretation indicates that bedrock is cropping out and that fluid flow features are mainly restricted to one area within the canyon. A video mosaic was generated above the fluid flow features to map the biological communities. This work finished early in the morning. Now, the ROV crew around Stig Vågenes is preparing the ROV for the sampling at the seafloor. A basket will be launched together with the ROV in order to store temporarily the collected material. During the first dive, we collected 5 carbonate crusts and 5 sediment push cores (Figure 3). Besides the science, our CAGE communication officer Maja Sojtaric takes care of the public outreach programme. On a sunny day like this, filming the action onboard is a pleasure.

Figure 2: Filming the science from a life boat. CAGE communication officer Maja in action.
Figure 3: Sediment push coring of bacterial mats.

Day 2, 08.08.2017

We reached our target area in the morning of 08.08.2017. The sea is still calm and the weather is excellent for ROV operations. Geochemical and micropaleontogical laboratories are ready for sampling (Figure 1). Here, we will measure the alkalinity and the iron concentration within the porewater samples. This will give us a first glimpse on the activity of the fluid flow system in the canyons. All other measurements including methane gas concentration will be done in laboratories at home and with our NORCRUST partners. Around 09.30 am, the first CTD cast was deployed for calibration purposes of the ROV Ægir 6000 (Figure 2). Thereafter the multibeam bathymetric survey started. The new data will have a resolution of less than 20 cm and will help us to define the sampling sites (Figure 3).  

Figure 1: The geochemical laboratory onboard G.O. Sars. Here, we measure the alkalinity and the iron concentration in extracted porewater from the sediment cores.

 

Figure 2: ROV Ægir 6000 are launched to its first dive for the bathymetric survey of the canyons.

 

Figure 3: Example of the seabed within the canyons. You see both bedrock and carbonate crusts. Whitish spots indicate the occurrence of bacterial mats at the seafloor

 

Day 1, 07.08.2017

The scientific party entered G.O. Sars in the early morning of 07.08.2017. We are four scientists from NGU (Jochen Knies, Aivo Lepland, Wei Li Hong, and Tobias Himmler), four scientists from CAGE-UiT (Arunima Sen, Haoyi Yao, Pierre-Antoine Dessandier and Kasia Melaniuk) as well as CAGE communication officer Maja Sojtaric. The Captain Hans Troland briefed us about the security system onboard, while a guided tour was given by the Chief Officer. The morning was used to unpack and store the equipment properly in the laboratories onboard G.O. Sars. A fire drill interrupted the lunch and coffee break. During the afternoon, Jochen introduced the goal and objectives of the cruise. The cruise is sponsored by the NFR Petromaks 2 NORCRUST project and its partners. The target area lies southwest of the Lofoten/Vesterålen and is situated along the continental margin at 750 m water depth. Two small canyons will be inspected for active fluid flow by ROV operation. Active fluid flow has been inferred from the presence of methane-derived authigenic carbonates and bacterial mats recorded in the frame of the MAREANO programme. We spent the afternoon in preparing the multibeam bathymetric survey with the ROV Ægir. Several lines will cover the southernmost canyon where we expect the presence of the fluid flow features. From the new bathymetric map with less than 20 cm resolution we will define the sampling sites for carbonate crust sampling, pushcoring, and free gas sampling. We will also sample the seabed with the gravity coring system onboard G.O. Sars. More exiting stories are soon to be published.

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