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2006 October 23
Weekly Topics from Chikyu #09 -Shimokita Shakedown Cruise- Back to list
PHOTO
Cuttings on a shale shaker. Separates mud from solids (cuttings) by vibration on a grid. There are six shale shakers on the Chikyu.
Week #09 [10/1-10/7]
Dr. Hideki Masago, CDEX staff scientist reports:

Riser drilling has finally started at the midnight of 4 Oct! After the previous coring, we had several wait-on-weather and equipment maintenance in riser tests, which caused a long break of drilling operation. Lab staffs were longing to see the operation restarted. In these days, the Lab Manager frequently go to the upper office (Drilling Engineers’ Office, which is above our Lab) to catch the latest situation. As it was only one day before my disembarkation, I was really satisfied and relaxed to see the riser operation.

This shakedown, we drill without coring in some intervals. In terms of pure scientific point of view, whole coring is desirable, but usually we are not able to retrieve 100 percent core recovery and it takes very much time. You may think there is nothing to do in the Lab without cores. That is not true. In riser drilling, cuttings - drilling wastes - are delivered to the surface with return mud. These cuttings provide us important geologic information as well as cores. In case of industrial drilling (oil, gas, and geothermal), cores are taken only in several important horizons, and the rest is described based on cuttings observation. To test onboard processing and analyses of cuttings in the Lab was one of the main purposes of this cruise, which is the first experience in oceanic scientific drilling.

Cuttings are taken by a Sample Catcher at the shale shaker located behind the rig floor. The Sample Catcher takes at the required depths (every 5 m in this time), and divides by each purpose. A part of them are delivered to the Mudlogger’s house and a Mudlogger takes a quick lithologic description. The rest of samples are delivered to a Wellsite Geologist who checks the sample and pass them to our Lab. However, our Lab and shale shaker are physically distant: they are located nearly head and aft ends of the 210 meter-long ship, respectively. So, we had close discussions for smooth sample and information flow between Lab Managers, Wellsite Geologists and Mudloggers.

After the dinner on 5th, the first cuttings were delivered to the Lab. Lab techs were curiously gazing them, as this was their first time. We gave sample codes on these samples, and then started processing. Cuttings needed somewhat different treatment from cores. It made some confusion to us, but we could finish processing for the first cuttings samples. In the next morning, I quickly finished registration of next samples onto the database before leaving the ship.

Week #10 [10/8-10/14]arrow

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