造山带超高压变质流体中气体组成及成藏条件初探

传统的油气地质研究和勘探开发几乎都是集中在盆地,而造山带作为板(陆)块的碰撞、会聚带,为无机成因气形成和释放的有利场所,是天然气地质理论研究的一个新领域。本文利用激光拉曼探针技术对大别造山带超高压变质岩中流体包裹体进行了成分分析,结果表明超高压变质流体中不仅含有CO₂(>50%)、H₂、N₂、H₂S等,还有高含量的幔源烃类气(CH₄等,含量最高达23.6mol%)。同时,超高压变质带中还发育有浅层碳酸盐岩及其它含碳岩石经动力变质作用可形成大量的CO₂气。大别超高压变质带中具有无机成因气成藏的可能条件,带内广泛发育的推覆构造、韧性断层及糜棱岩可以作为无机成因气成藏的圈、盖和保存条件。本文成果可为油气地质研究和勘探开发提供新的思路、方向和领域。

GAS COMPOSITION IN ULTRA-HIGH PRESSURE METAMORPHIC FLUID AND GAS POOL-FORMING CONDITIONS IN OROGENIC BELT

Traditional oil\|gas geological study and exploration\|development almost concentrated in basin. The collisional and sutural belt of plates (or landmasses), orogenic belts being advantageous places where abiogenic gas produce and discharge, this is a new field in natural gas geological study. The components of fluid inclusions in ultra\|high pressure metamorphic rocks in the Dabie orogenic belt were analyzed with laser Raman probe technology. The study results show that there are not only CO\-2 (>50%), H\-2, N\-2, H\-2S etc., but also high content gas of mantle\|derived hydrocarbon (CH\-4 etc., amount to 23 6%). Meanwhile, there are enormous CO\-2 originating from carbonate rocks and other carbon\|bearing rocks in shallow synthem through dynamic metamorphism in the Dabie ultra\|high pressure metamorphic belt. The formation conditions of abiogenic gas can exist in ultra\|high pressure metamorphic belt where nappe structure, ductile fault and mylonite can turn into the trap, cover and conservative conditions of abiogenic gas. Study results provide new thought train, direction and field for oil gas geological study and exploration\|development.