View 3: second petrophysics blog from the ship
So the time
has come, the boat is fuelled, the labs are fully prepared and we are all ready
to depart from the port in Corinth to our first site in the gulf. Very soon I
will be bobbing up and down on the Gulf of Corinth as we drill into the seabed
below us in an attempt to discover how it would’ve looked to witness the gulf
appear over the past 5 million years (more on the expedition aims here).
Sunrise on the day of departure
The offshore
team has now expanded as we have been joined by a subgroup of
the scientists from the science party involved in this project. 9 of the 31
total. These scientists will be assisting with running the labs offshore and
completing some of the initial analysis and sampling. The job is not a too
privileged position though since the cores won’t be split until they reach the
Onshore Science Party (OSP) in Bremen, Germany, during January of 2018. Since
there is a little delay between recovery and full analysis of the cores, all of
the ephemeral properties of the sediments (those that degrade in quality with
time) and essential sampling (drilling mud, pore water, microbiology etc.) will
be completed with the help of these 9 scientists on the vessel within the first
hours of recovery. As one would expect, the doubling of the team size has
affected the group dynamic on board the vessel. However the thing to remember
about these 9 new team members is that they are all heavily invested in the
science and will be completing research using the data produced by this
project, each with their individual spins and focuses. This aspect defines the change.
All 9 are all so passionate about the work and excited to be here. It’s
infectious.
The Fugro Synergy at port in Corinth
Owing to all
this, my next two months will be very different from the usual 9-5 office job.
So what will I be doing for this time? I will be working on the opposite 12
hour shift to my work partner to ensure 24 hour continual operation of the Multi-SensorCore Logger .
The Multi Sensor Core Logger (or MSCL) is an apparatus that measures ephemeral
physical properties of rock and sediment cores, now I know that sounds boring
when I explain it like that in full but bear with me. The Geotek™ system that I
will be using is a fully automated track system where the cores themselves are
moved through stationary sensors rather than there being moving sensors or
probes. The process is almost fully automatic and generates masses of data at a
great resolution. It really is very cool piece of kit.
MSCL lab
This will
not the first time that I have used one, personally I have used this system
before as well as using similar systems on other projects such as the Geotek
XYZ system during the onshore phase of IODP expedition 357:
Atlantis Massif; and using EPC’s bespoke MSCL: Fast-track for training during
the Petrophysics Summer School 2016
and Petrophysics Summer School 2017.
So what does
the MSCL do exactly and what is my (and my scientist partner’s) job as the
operator? Well to be perfectly honest it is fairly simple to understand and
operate if you have a basic understanding of material properties. The 5 properties that it measures in order are
density, p-wave velocity, electrical resistivity, magnetic susceptibility and
natural gamma radiation. Density is fairly self-explanatory. The MSCL though
records electron density which is almost exactly the same as bulk density for the
suite of elements that make up rock-forming minerals. P-wave velocity describes
the speed with which an acoustic pulse (or sound wave) travels through a
material, the electrical resistivity of a material is the inverse of its
electrical conductivity and natural gamma radiation simply describes the
natural gamma radiation output of the rock or sediment. Magnetic susceptibility
on the other hand is bit less straightforward. It is most simply described as
the degree by which a rock can be magnetised by an external magnetic field and
in sedimentology it is most widely used to infer clay proportions in sand
through the recognition of iron content.
My job as
operator of the MSCL is to ensure that it is running and continually logging
core for the full 12 hours of my shift, with my partner taking care of the
other half of the day. This is important because the logger can complete
measurements on 3 metres of core in just over 1 hour and therefore only keeps
up with everything else if it is operating 24/7. It’s a busy task but we have
air conditioning, speakers and a coffee machine in the container to make sure
that we are comfortable and sufficiently caffeinated.
If all goes
to plan this expedition will recover over 1500 m of core from the Gulf of
Corinth. And that’s a busy MSCL (and busy operator!).
Where I will
be working for the next couple of months is just the one of the many labs on Main
Street. There are also labs for curation, geochemistry and a combined science
office for microscopy, visual core description, palaeontology and
core-log-seismic integration. But for more info on those labs keep an eye on
the Expedition 381 blog over
the coming months.
Laurence
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