中国天然气勘探的两个重要领域

TWO ESSENTIAL GAS ACCUMULATIONS FOR NATURAL GAS EXPLORATION IN CHINA

依据成藏过程和原理,天然气藏可被划分为常规圈闭气、根缘气、煤层气、页岩气、溶解气(含水溶气)以及天然气水合物等类型。除水溶气和天然气水合物以外,上述其他四种类型气藏均已在北美实现了工业化勘探开发。为此分析了中国相关盆地的地质特点以及油气成藏条件,结果认为:①上述前四种类型气藏也是中国天然气勘探所面对的基本对象,尤其是其中的根缘气和页岩气具有重要的现实意义,是中国天然气勘探值得重视的两个基本领域;②根据储层致密、源储接触以及砂岩底部含气等特点,可对根缘气发育进行早期判识,中国的根缘气分布可划分为三区四块,以致密砂岩底部含气作为识别标志,简化了识别方法并有可能发现更多的根缘气藏;③页岩气具有典型的无或短距离运移、自生自储、隐蔽成藏以及较强的抗构造破坏能力等特点,中国南方碳酸盐岩地区、西北地区及华北地区中、古生界等均是页岩气勘探的重要领域,其中尤以南方地区,四川、鄂尔多斯、吐哈等盆地最值得关注。

Natural gas can be classified as conventional reservoir gas, source-contacting gas, coal-bed methane, shale gas, water-soluble gas and hydrate on the basis of the accumulation principle and process. Excepted for water-dissolved gas and gas hydrate, the other four types of gas accumulations have been hugely succeeded in North America. According to the reservoir conditions and geological features of basins in China, these four types of gas reservoir are the basic objects for China's gas exploration, in particular, the source-contacting gas and shale gas accumulations. The two kinds of gas accumulations are now respectively the second and the fourth largest category of natural gas accumulations which are put into industrial exploration and development in the United States. Source-contacting gas reservoirs can be easily recognized by the factors such as tight reservoir, contacting of source and reservoir, and gas-bearing at the bottom of tight sand, and so on. The area of Source-contacting gas in China can be divided into three regions and four sections. Shale gas is characterized by typical short-range migration, self-source and self-reservoir, subtle accumulation, and strongly anti-destruction capability. The relative important areas for shale gas exploration in China are carbonate strata area in South China, Mesozoic and Paleozoic in North China and Northwest China, especially in Sichuan, Ordos and Turpan-Hami Basins.