中国天然气地质特征及勘探前景

从盆地分析入手,以热作用为主线,用动平衡观点研究中国天然气地质特征是我们的总体思路。以盆、热、烃为理论基础,围绕天然气形成环境和资源分布,本文提出了三种相互关联的盆地综合分类(热分类,构造分类及油气资源比例分类)。中国天然气主要来源于四个领域(未熟层系、含煤层系、碳酸盐岩系和湖相碎屑岩系),分属五种成因类型(生物气、生物-热催化过渡带气、油型气、煤成气及深源气)。大、中型气田形成的地质条件是:一定的生气强度;厚度较大的常规储层;生气期与成藏期较晚;发育有古隆起与古圈闭;有良好的区域盖层;有断层及不整合面为输导等地质因素的综合结果。主要有四大含气领域(煤成气、海相碳酸盐岩气、湖相腐泥气和生物气),四大含气区的资源前景序次是:近海气区、西北气区、中部气区和东部油气区。中国今后天然气勘探的总方针是大中小型并举,远中近期兼顾。

GEOLOGICAL PROPERTIES AND EXPLORATION PROSPECTS OF NATURAL GAS IN CHINA

The main idea of studying the geological properties of natural gas in China is that to start from basin analysis,take thermal effect as fundamental principle,and use the view-point of dynamic equilibrium.Based on the theory of the relationship between basin,ther-mality,hydrocarbon,centered on the formation environment and the resources distribution of natural gas,three kinds of interrelated classification such as thermal,structural and oil-gas resources proportional classfications of the basins were proposed in this paper.Natural gas in China is mainly come from sets of immature sequences,coal-bearing formations,carbonate rook series and lacustrine clastic rooks,and belongs to five genetic types named as biogenic gas,biogenic-thermal catalytic gas,sapropelic gas,humic gas and deep sourced gas.The geological conditions to form big-and medium-size gas fields are:1.certain gas-generating capacity;2.conventional reservoir of considerable thickness;3.late gas-generating stage and pool-forming stage;4.the development of paleo-uplift and paleo-traps;5.favourable regional caprocks;6.faults and unconformities as passage ways forgas migration.There are mainly four gas-bearing domains in China including humic gas,marine carbonate rock gas,lacustrine sapropelic gas and biogas.They are mainly distribut-ed in four major gas provinces which are arranged in the following order:offshore North-west China,Central China and East China oil and gas provinces.The general policy fornatural gas exploration in China is"to explore large-medinm-and small size gas fieldscontemporaneously and to give consideration to long,medium and short terms planning"