中纬度带天然气水合物地球化学勘查技术

祁连山冻土区木里地区天然气水合物矿藏是迄今为止在中纬度带首次发现的水合物矿藏，为了研究中纬度带水合物地球化学勘查技术，选择木里矿区作为方法技术的试验区。试验指标内容有土壤顶空气、酸解烃、碳酸盐和甲烷碳同位素。研究表明:祁连山木里天然气水合物矿藏存在明显的近地表地球化学异常；由甲烷碳同位素和烃类组成判断地表油气化探异常为热解成因，指示该区天然气水合物成藏物质来源于油气和煤成气。进一步研究了中纬度带冻土区天然气水合物成藏模式,指出该区进行天然气水合物勘探的同时应进行石油和煤成气的综合勘探。

Geochemical Exploration Technology of Natural Gas Hydrate in Middle-Latitudes Permafrost Zone

The first discovery of gas hydrate reservoir in middle-latitudes zone was made in the Qilian Mountain permafrost zone. To evaluate the geochemical exploration method for gas hydrate in middle-latitudes zone, Muli area was chosen as the test area. Soil headspace gas, acid extracted hydrocarbon, carbon isotope of methane and carbonate were tested. The results reveal that geochemical anomalies were consistent with the gas hydrate reservoir underneath. The carbon isotope of methane and hydrocarbon composition analysis of the surface geochemical anomaly zone indicated a thermo-pyrogenation origin, suggesting the gas source of the potential gas hydrate reservoir in this area may contribute by oil gas and coal-formed gas. The origin model was also studied for the gas hydrate reservoir. An integrated exploration project which targets at gas hydrate, oil and coal bed methane altogether was recommended as the next step in Muli area.