2001 Volume 66 Issue 2 Pages 215-224
Minami-Kanto gas field yields natural gas dissolved in water from the formations consisting of alternating thin beds of sandstone and mudstone. As its remarkable feature, there are regions which show so-called Mobara type gas production behavior characterized by both increase of gas water ratio and rapid depletion of reservoir pressure.
A series of laboratory experiments was carried out using X-ray CT scanner in order to investigate the fluid behavior in mudstone because most of the produced gas is considered to be supplied from very low permeable mudstones in this region. In each experiment, gas flow rate was measured with incremental drop of pore pressure, while the effective confining pressure was maintained so as to prevent the core from compaction.
Our experiments showed that the existence of free gas in mudstone greatly contributed to the Mobara type gas production behavior, and that the mudstone beds might act as reservoirs for gas fields showing the Mobara type gas production behavior.
