Cretaceous Of Hokkaido Research Articles

Japan Petroleum Exploration Co., Ltd. was established in accordance with the Japan Petroleum Exploration Co., Ltd. Law No. 152 of August 1955. We have been carrying forward an operation of petroleum and gas development on a five-year program; its basic policy consists of the following 5 principles. 1. 2. Exploration of the plain area and the bottom of continental shelf. 3. Exploration of the Cretaceous. 4. 5. Exploration of major structure in area of low relief terrain and deepening of the existing oil fields. The followings are the main oil and gas fields discovered before the end of fiscal year 1958, the 4th year of a 5-year program: Oil fields-Barato, Sarukawa, Tsuchizaki-oki, Fukura, Amarume, Tamugiyama and Mitsuke. Gas fields-Higashi-Niigata and Higashi-Sanjo. Estimated oil and gas reserves in these fields are about 4, 880 thousand kl (including converted gas). Finding cost is ¥2, 300 per kilolitre and discovered reserve is about 30, 000 kl per well. Newly discovered oil bearing horizons are Tobetsu formation (Pliocene of Hokkaido) and Oguri-yama tuff formation (Middle Miocene in Niigata Prefecture). The latter attracted special interest by producing 200 kl/d (bean 7mm) of oil from acidic volcanoic rock in the above mentioned tuff. Structurally the characteristic reverse fault of low angle found in Sarukawa oil field had never been known so far in the oil fields of Japan and gives us a hint on the underground structure of the neck pert of Oga Peninsula. Exploration of offshore oil field will be a big problem to be faced in future. The Cretaceous of Hokkaido has proved great potentiality by the analytical result of its organic matters. By comparing operational load to the plan of five-year program, prospecting area gives 82.7%, wildcat wells 89.7%, total meters drilled 64.8% and discovered reserves 77.5%.