青海木里三露天井田煤系天然气水合物成藏模式与勘查开发建议

天然气水合物因其能量密度巨大、使用方便、燃烧值高、清洁无污染等特点,被誉为21世纪最有希望的战略资源,是常规油气资源的潜力巨大的一种替代能源.青海木里地区三露天井田天然气水合物的发育是该区含煤岩系的充足气源和高寒山区适宜的水合物稳定带耦合作用的结果.将赋存在煤系中的天然气水合物定义为煤系天然气水合物,并将其纳入煤系非常...

Accumulation model and exploration and development suggestions of coal measure gas hydrates in Sanlutian area of Muli Coalfield,Qinghai Province

The Natural Gas Hydrate(NGH) is known as the most promising strategic resource in the 21st century because of its huge energy density, convenient use, high combustion value, and cleanness, and it is an alternative energy source with huge potential for conventional oil and gas resources. The occurrence of the NGH in the Sanlutian area of Muli Coalfield in Qinghai Province is the result of the interaction between the abundant gas sources and the hydrate stability zone in cold highland areas. The NGH in coal-bearing strata is defined as the coal measure gas hydrate, belonging to unconventional coal measure gases. To find out its close connection with coal measures and its metallogenic specialization, the accumulation conditions of the NGH are studied, and proposals for the exploration and development of the NGH are put forward in this paper. The results show that the NGH in coal measures in the Sanlutian area of Muli Coalfield is characterized by both coal-type gases and oil-type gases, and the enrichment layers are concentrated in the upper part of Jiangcang Formation of the middle Jurassic in the temperature-pressure stable zone. The reservoirs of the NGH can be divided into “fracture type”, “fracture + pore type” and “pore type”, of which the proportion are 65.22% 26.08% and 8.70%, respectively. Based on the present tectonic pattern, the Sanlutian area is divided into eight blocks, and the favorable enrichment areas of NGH are the M₁, S₁ and S₂ blocks with the development of reverse faults, low dip angle of strata, and medium to low fracture density. The accumulation mode of the NGH in coal measures in the Sanlutian area is established, that is, imbricate fan structure and frozen soil zone plugging type. The mixed gas source filling, short-distance migration, and tectonic trap are favorable factors for the NGH accumulation. Finally, with the coal measure NGH in the study area as an example, the basic characteristics of the terrestrial coal measure NGH are summarized, and three stages of the exploration and development of the NGH in the permafrost area in China are proposed. It is considered that co-exploration and mining is an inevitable way to develop the NGH in coal measures.