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Gas MonitoringAugust 11, 2012

Good morning. Today, I will introduce the “mud gas monitoring” work. Four scientists, including me, will undertake this research onboard the Chikyu.

In this cruise, we will drill deep - down to 2,200 m below the seafloor - by using the riser drilling system. In this type of system, drilling mud is circulated to control the borehole pressure and to lubricate the drill bit. When the mud circulates, small fragments of sediments and water, or gas trapped in the sediment, are also carried to the ship. Four of us will monitor the change of chemical compositions in the sediments.

Once, I asked a drilling engineer, “Why do we call this Riser Drilling”. He answered, “The riser drilling system has been used for oil drilling. Circulating mud or oil rises along the pipes, so we call it Riser Drilling”. I got it. But in this expedition important scientific information will rise up instead of oil.

Natural gas is closely related to the microbial activity in the sub-seafloor. For example, it is known that there is a microbe that produces methane as a metabolic byproduct from hydrogen gas and carbon dioxide. We can detect high microbial activity by monitoring the chemical compositions of methane and other gases.

Marshal Bowles (He just arrived yesterday by a helicopter and joined as new member, Bremen University), me, and Wei-Li Hong (Oregon State University)
in the new gas-monitoring laboratory on the Chikyu.

Gas-monitoring laboratory is in a converted container near the derrick far from the ordinary laboratory area near the front. We will work in this lab on rotating shifts so we work 24 hours a day. In fact, this is the first run of the scientific gas monitoring system that was introduced last year on the Chikyu. The lab is crowded with new and shiny apparatuses waiting for the rocks to come up from the deep well. Of course, we are waiting for that with great expectation and anxiety. We in the gas monitoring team are really excited because we should be the first people to get new scientific data ahead of anybody else onboard just after the start of drilling!

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