ODP Technical Note 10


C. PCS Operation and Plans for Additional Development

The PCS is free-fall deployed and is rotated with the BHA similar to the XCB. Once the core sample has been cut, the rig pumps are shut off, and the coring wireline is attached to the PCS. The PCS is picked up off the BHA landing shoulder to release the actuation ball, then lowered back onto the BHA landing shoulder. The rig pumps are reengaged to pressurize the drill string, which actuates the actuator subassembly, stroking the sample chamber closed. The PCS is then retrieved via the coring wireline. Once on deck, the detachable sample chamber is removed and placed in a temperature-controlled bath. A sampling manifold can be attached, and gas and/or fluid samples extracted.

Recovering a pressurized sample from the seafloor is only half the battle. As concluded by the participants at an ODP workshop on pressure core sampling, "the most important improvement to be made remains in the design of a system that subsamples gas, interstitial waters, and sediments without depressurizing the sample". At present there is no mechanism for extracting a solid (sediment or hydrate) sample under pressure from the PCS; solid core samples must be depressurized to access. Enhanced capabilities for accessing fluid, gas, and solid samples under pressure, and for conducting laboratory tests of these materials at in-situ conditions, constitute Phase II of PCS development. This level of PCS development has been put on hold pending funding of a scientific proposal by third-party investigators to develop a pressurized laboratory chamber.

To Third-party and Developmental Tools, Section A.
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