中美页岩气成藏条件、分布特征差异研究与启示

美国页岩气大多为海相热成因型,产气页岩主要分布在前陆和克拉通盆地的泥盆—石炭系,埋藏深度一般为1 500～3 500 m。我国页岩分为海相、海陆过渡相与煤系、湖相三类,其中海相页岩主要发育在坳拉槽和克拉通盆地的下古生界,富有机质集中段分布稳定,热成熟度偏高,有较高的含气量,勘探前景最好;海陆过渡相与煤系页岩主要发育在大型坳陷和前陆盆地,层系以石炭系—侏罗系为主,没有明显的富有机质集中段,含气量差别较大,勘探潜力有待落实;湖相页岩主要发育在中、新生代陆相盆地,富有机质集中段厚度大,成熟度较高的凹陷中心区可能具有一定资源前景。预测我国页岩气勘探将经历较长的探索期,未来年产量可达500亿～600亿m3规模。

Comparison and enlightenment on formation condition and distribution characteristics of shale gas between China and U.S.

Shale gas in America mostly comes from thermogenic marine shales, and gas shales mainly distribute in Devonian and Carboniferous of Foreland and Craton basins, while the buried depth is 1 500~3 500 m. Shales in China include 3 types: marine, transitional and lacustrine. Marine shales basically distribute in the lower Paleozoic of Aulacogen and Craton basins;organic rich concentrated parts are steady going,and thermal maturity phase and gas content are high,so the explorational prospect is the best. Transitional shales mostly distribute in Carboniferous Jurassic of Foreland and Craton basins;there is no obvious organic rich concentrated part, and gas content changes greatly, so the explorational potential needs to be proved. Lacustrine shales typically distribute in Mesozoic and Cenozoic of rift and Craton basins;organic rich concentrated parts are thick and stable, and explorational potential is probably great in center of depression which reaches generating gas stage.It is forecast that shale gas exploration will take a long time and output will be 50 billion~60 billion m3 in the future.