北蒲原平野における石油•ガスの移動,集積機構に関する1考察
1977 年 42 巻 2 号 p. 139-147
詳細
1977 年 42 巻 2 号 p. 139-147
During the last decade, many arguments have arisen about the generation, migration and accumulation of hydrocarbons. Improvement of geochemical field and the study of physical properties of hydrocarbons contribute to solve the above subject.
The writers studied Kitakanbara area, northern part of Niigata prefecture, where active hydrocarbon exploration and development have been made. As a result of the exploration and development of the hydrocarbon in this area, many kinds of the data on the subsurface petroleum geology were collected, and published. In this paper the subject is discussed as follows: 1. distribution and deposional mechanism of reservoir facies, 2. a change of chemical composition of hydrocarbon at each producing oil and gas field and thermal effects.
Paleodeposional system of reservoir facies is different at each geological stage. The sands of the Teradomari and Shiiya formation are transported lateraly from local source area. On the contrary, the sands of Nishiyama formation are widely derived from Kushigata mountain range area. Their distribution indicate a close relationship between the migration mechanism and the forming of accumulation of hydrocarbon. A significant change of chemical composition of hydrocarbon reflects the migration distance (mobility) and a grade of water washing. These data show that the Shiiya formation generates hydrocarbon in surrounding Shintainai area, which then migrated to Hirakida gas field with oil and gas segregation facies, and then medium gravity crude oil is transfered to Echigo-Kurokawa under the controls of differential entrapment. These migrations occured between the Nishiyama stage and Haizume stage that is simultaneous developing and forming this basin. This oil varied to the heavy oil after accumulation by water washing effect.
