陆域天然气水合物形成条件理论研究及其对青南多年冻土区水合物勘查的启示

Review and Progress:Theoretical Research on Formation Conditions of the Land Gas Hydrate and Its Implications for Hydrate Exploration in Permafrost Regions in Southern Qinghai Province

陆域天然气水合物作为一种未来开发潜力最大的非常规清洁能源而备受各国政府青睐,目前国内外对陆域水合物形成条件的研究集中于4个重点方向:温度-压力、气源、气体运移及水合物的圈闭,大量的研究表明最为直接的条件为温度-压力和气源,而圈闭则决定水合物的成藏规模。同时水合物的形成机制也成为研究的热点。近年来,我国学者依据陆域水合物形成的温压条件而做出的理论预测曾成功地指导了祁连山冻土区水合物的发现。然而,地处海拔4 600多米的北羌塘青南冻土区有着比祁连山水合物产出地更佳的水合物形成条件,但至今未获得找矿成果突破,还存在二叠系烃源岩中有机质的沉积环境不明、气体成因不清及烃源岩综合评价缺乏标准等诸多问题。对国内外在水合物形成条件等方面进展的总结将给青南地区今后水合物勘查诸多有益的启示,如冻土厚度及类型、烃气成因、断层、圈闭和储层等因素对水合物形成及成藏等方面的影响。

Land gas hydrates,as a potential future unconventional clean energy with largest potential is highly favored by governments.Currently,researches on land hydrate formation conditions are concentrated on four key directions：temperature-pressure,gas source,hydrocarbon gas migration and traps.Many studies show that temperature-pressure and gas source are the most straightforward conditions,and the traps determine the size of hydrate accumulation.At the same time,the formation mechanism of hydrate is becoming a hot spot.In recent years,scholars in China have successfully discovered gas hydrates in Qilian permafrost based on the hydrate formational temperature and pressure conditions.However,the northern Qiangtang,located at an altitude of 4 600 meters,has better conditions of the hydrate output than Qilian mountains,but has not yet fully studied,leaving some unsolved problems such as sedimentary environment of organic gas in the Permian hydrocarbon source rocks,genesis of hydrocarbon gas and hydrocarbon source rock evaluation.The summary of the progress of hydrate formation conditions at home and abroad provides a green future and beneficial enlightenment for the hydrate exploration in the southern Qinghai Province,such as frozen soil thickness and types,hydrocarbon gas causes,fault trap and the reservoir factors,as the impact on hydrate formation and accumulation.