グリーンタフ貯留岩の地層流体

新潟地域グリーンタフ炭化水素鉱床の石油地質学的研究 その2

抄録

Geochemical studies were carried on formation fluids including gas, oil, condensate and formation water in reservoir rocks in the Green Tuff, especially in the Mitsuke oil field, and in the Shiunji, Yoshii-Higashi Kashiwazaki and Minami Nagaoka-Katakai gas fields.
Properties of oils and condensates seem to depend on temperatures of reservoir rocks, whereas those of gases reflect the conditions of their generation.
The origin of gases is considered to be thermogenic based on the data of δ¹³C₁ and C₁/∑C_n. Both data of δ¹³C₁ and i-C₄/n-C₄ indicate that the level of maturation of source rocks in the Minami Nagaoka-Katakai and Yoshii-Higashi Kashiwazaki gas fields is higher than that in the Mitsuke oil field and Shiunji gas field.
Chemical composition of formation waters is closely related to alteration of reservoir rocks. The Cl^- contents of formation waters in the Mitsuke oil field increase from SW to NE, which suggests that interstitial waters in the Teradomari formation flow from SW to NE.