关键词: 接触变质作用, 圆台模型, 二氧化碳, 释放规律, 二氧化碳气藏, 郯庐断裂带

Abstract: The releasing rules of carbon dioxide under the condition of contact metamorphosis were systematically studied, and the releasing amount of carbon dioxide was calculated by modeling. Taking marble of Shuangshan area in southern Tanlu fault belt as an example, the surrounding rocks and intrusive body for controlling carbon dioxide releasing under the condition of carbonate rock metamorphism were investigated. The results show that the releasing amount of carbon dioxide has close relation with the characteristics of the surrounding rock including thermal conductivity of surrounding rock as well as permeability, porosity and connectivity of rock. The compositions of intrusive body, intrusive depth, scale and occurrence under the action of contact metamorphism of surrounding rock have the important influences on carbon dioxide releasing. The occurrence of the intrusive body resulted in a great deal of fractures in the surrounding rocks and thus made fluid flowing and accumulation easily. The full evidence proved that the carbon dioxide produced under contact metamorphism condition could form an industrial-scale inorganic natural gas reservoir in some conditions. On the basis of theoretical and practical study, a circular cylinder model for determining carbon dioxide releasing amount under the contact metamorphism was proposed. It is suggested that the exploration of carbon dioxide reservoir should also be paid attention to the outside oil-and-gas bearing basins.

Key words: contact metamorphism, circular cylinder model, carbon dioxide, releasing rule, carbon dioxide reservoir, Tanlu fault belt