The first submarine test boring for oil in Japan was executed by the late Tokusaburo Iwasa in the sea 1, 970m off Michikawa-mura, Yuai-gun, Akita Prefecture using a springg pole drilling machine (Kazusa-bori) in the summer of 1952. The drilling was cotinued until it reached the depth of 27m from the sea bottom and abandoned after the machine was hit and damaged by a typhoon of August 19, 1952. As noticed from the geological column accompanied in this note, the sediments consist of the Recent sand at the depth of 0-3m intercalating two thin grabel layers, of dark gray mudstone at 3-10m and of another dark-coloured mudstone at 10-27m intercalating layers of tuffaceous sandstone, and showing a distinct alternation of the dark-colored mudstone and tuffaceous sandstone, while in the upper portion of this part (10-27m) the mudstone is much more dominant. The fossil foraminifera from the dark-coloured mudstone is characterized by the flood of Goesella schenchi (Table I). From the fossil evidence, the sediments except for the uppermost sand and gravel, may be correlated with the Funakawa formation of middle Miocen age typically developed on the adjacent land area. A fairly large amount of gas and oil of good quality was found in tuffaceous sandstones within the depth of 25-27m. Other gas and oil seeps in the sea are found off Matsugasaki-mura, 12m south of Michikawa. All the stratigraphical work ever done in the adjacent land area leads us to believe that these two localities of gas and oil seeps just mentioned are related to the similar anticlinal structure to the south of Fakasawa in Matsugasaki-mura, which once produced oil.
Among effective thinners and emulsifiers, writers have been investigating for several years. And oxidized products of lignites that have been recently obtained by treating them with dil.-HNO3, have been found best. Those oxidized products were used at Akita fields resulting better effects upon water-clay muds and cement cut muds.
Chiyoda-hamlet of Ikeda-town is situated about 20km east from Obihiro-City. In this place, 7 gas producing wells were drilled during recent two years. These wells have a depth of about 125±5m, and flow out naturally the gas with water, showing relatively high tamperature. Total daily production from these wells is nearly 155m3, and the mean value of gas water ratio is about 1:4.1. Cl- content in this under-ground water ranges from 1045 to 1720mg/L. So the writers recognized this deposits as a brackish type. And these gas producing beds probably belong to the Ikeda formation (upper-most Pliocene). Stratigraphical and areal distribution of natural gas is nearly unknown, but in this paper the writers discussed on the geochemical characters.