Experiments on interstitial water squeezing at high pressure using water-gathering plates

抄録

A sediment squeezing tool for use in interstitial water extraction at the onboard laboratory of D/V Chikyu was modified for use at pressures up to 112.3 MPa. A pair of titanium water-gathering plate originally developed by Central Research Institute of Electric Power Industry (CRIEPI) replaces a thin mesh to allow squeezing of sediment at a higher pressure without jamming of sediments. The modified tool endured a longer period of squeezing at high pressure, and yielded greater volume of interstitial water in test experiments. The acquired fluid sample composition showed no major changes even at the pressure of 112.3 MPa, although further tests must be conducted to assess the potential dehydration of clay mineral at high pressures. However, squeezing of sandstone of approximately 12％ porosity yielded no interstitial water at all, showing system limitations for low-porosity samples. The improved tool and the data from these experiments are expected to be useful when low-porosity sediments from a deep hole are obtained.