中国冻土区天然气水合物的找矿选区及其资源潜力

Resource potential and reservoir distribution of natural gas hydrate in permafrost areas of China

中国是世界第三冻土大国,多年冻土面积达2.15×106km2(主要分布于青藏高原和东北大兴安岭地区),蕴含丰富的天然气水合物资源。前人对中国冻土区天然气水合物的研究多局限在青藏高原,且在找矿预测特别是找矿选区方面的研究较少。为此,对中国冻土区天然气水合物成矿条件及找矿选区进行了深入讨论,并初步评价其资源潜力。根据形成天然气水合物的气源条件、温压条件,结合目前所发现的异常标志,认为中国冻土区具备良好的天然气水合物形成条件和找矿前景,羌塘盆地是形成条件和找矿前景最好的地区,其次是祁连山地区、风火山—乌丽地区和漠河盆地,接下来还有青藏高原的昆仑山垭口盆地、唐古拉山—土门地区、喀喇昆仑地区、西昆仑—可可西里盆地以及东北的根河盆地、拉布达林盆地、海拉尔盆地和新疆北部的阿尔泰地区等。采用体积法和蒙特卡罗法初步估算出中国冻土区天然气水合物资源量约为38×1012m3,相当于380×108t油当量,与中国常规天然气资源量基本相当,显示出巨大的资源潜力。

China is the third in the world with a permafrost area of 2.15×106 km2,which is mainly distributed in the Qing-Tibet Plateau and the Daxing'anling area of Northeast China,where natural gas hydrate resources are extremely rich.Such related studies by the predecessors are most found to focus on the Qinghai-Tibet Plateau,while few studies have been conducted on the reservoir forecast and distribution of natural gas hydrate.In view of this,a further discussion is made on the forecast and distribution of natural gas hydrate reservoirs in the permafrost area of China as well as a preliminary assessment on its resource potential there.According to the generation conditions of natural gas hydrate including gas source,temperature and pressure,in combination with the currently discovered abnormal indicators,it is concluded that the permafrost area is favorable for the formation and accumulation of natural gas hydrate,the Qiangtang Basin will be the best target with a good prospect for natural gas hydrate reservoirs,next to that are the Qilianshan Mountainous area,the Fenghuoshan-Wuli area,and the Mohe Basin,and the next are those areas distributed in the Qinghai-Tibet Plateau like the Kunlun Pass Basin,Tanggula Range-Tumen,Karakorum region,and West Kunlun-Hoh Xil Basin,in Northeast China like the Genhe Basin,the Labudalin Basin and the Hailaer Basin,and in the northern Xinjiang like the Altay Mountainous area.The most important of all,natural gas hydrate has been discovered in the Muli area of the Qilianshan Mountain.The volumetric and the Monte-Carlo methods were adopted to calculate the resource reserves of natural gas hydrate in the permafrost area of China to be 3.8×1013m3,being 380×108 t in oil equivalent.This calculation proves that there is a great potential for natural gas hydrate resources which are almost as much as the conventional natural gas resources in China.