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接触变质型天然气是无机成因气的一种重要类型。研究区闪长岩体与白云质大理岩的接触带为一高地热梯度和低压变质带。强烈的岩浆—流体与围岩发生矽卡岩化以及白云质大理岩的分解反应,源源不断地释放出二氧化碳。接触变质反应程度和二氧化碳的释放量随着距离岩体越远而减弱变小。不同部位接触变质反应和脱碳模式不同。这种类型的无机成因气在中国东部广大地区尤其盆地中具有较好的成藏条件,即位于地下浅部的中小型侵入体,附近发育有穹隆背斜、断块或潜山—披覆构造等圈闭条件,上部发育有泥页岩、致密碳酸盐岩或滑脱层中的糜棱岩等作为封盖层。
Contact with metamorphic natural gas is an important type of inorganic gas. The contact zone of diorite body and dolomitic marble in the study area is a high geothermal gradient and low-pressure metamorphic belt. Strong magma - fluid and surrounding rock skarnization and decomposition of dolomitic marble, the steady release of carbon dioxide. The degree of contact metamorphism and the release of carbon dioxide diminish with the distance from the rock mass. Different parts of the metamorphic reaction and decarburization patterns are different. This type of inorganic gas has favorable reservoir forming conditions in vast areas in eastern China, especially in the shallow and shallow intrusions, with dome anticlines, fault blocks or buried hill-drape structures For the trapping conditions, there are shale in the upper part, mylonite in the tight carbonate rock or skidding layer, etc. as the capping layer.