Abstract:

Based on thinsection observation, Raman analysis of minerals, rock and clay minerals analysis, and fluid inclusion analysis, and combined with burial history analysis, this paper discusses the diagenetic characteristics of deep reservoir in Minfeng Area, Dongying Sag. It was recognized that the deep reservoir had abundant diagenetic appearances and the characteristics of superimposed multiple diagenetic environments, such as acidic environment, alkaline environment, and alternating acidic and alkaline environments. The fluid inclusions represented different diagenetic environments were used to analyze the changes of diagenetic environments. The results showed that the depth ranging from 3000 m to 3200 m was a very important interval of alkaline fluid action. From shallow to deep, the diagenetic environments of deep reservoir in Mingfeng Area underwent a process from alkaline or alkalescent (shallower than 1750 m) to acidic (1750-3200 m), to alternating of acidic and alkaline (3200-4000 m), to alkaline (4000-5000m), and to alkalescent or weak acidic (deeper than 5000 m). The process of diagenetic environmental changes resulted in current complex diagenetic appearances. Depth and temperature were the macro dominant factors for the diagenetic environmental changes, but not the absolute control factors. The alternation of fluid property in local area might have caused the changes of diagenetic environments more directly.

Key words: deep reservoir, acidic diagenetic environment, alkaline diagenetic environment, fluid inclusions