全球古生界海相碳酸盐岩大油气田特征及油气分布

Characteristics and hydrocarbon distribution of the Paleozoic giant marine carbonate rock oil-gas fields in the world

古生界海相碳酸盐岩油气对中国能源安全具有重要意义。以全球古生界海相碳酸盐岩大油气田的最新资料为基础,系统统计分析了古生界海相碳酸盐岩大油气田的地质特征及其分布规律。截至2013年底,全球15个含油气盆地中共发现了89个古生界海相碳酸盐岩大油气田,油气可采储量达495.9×10^8t油当量,占全球海相碳酸盐岩层系油气总储量的20.9%。研究表明,大油气田分布在中东、前苏联、北美和亚太地区,其中,大油田主要分布于前苏联和北美,大气田则主要位于中东和亚太,20世纪70年代是大气田发现的高峰期。大油气田的油气主要来自古生界烃源岩,以志留系、石炭系、二叠系和泥盆系（按重要性排序）为主;烃源岩岩性主要为泥页岩、沥青质泥页岩和沥青质碳酸盐岩。盖层以蒸发岩和碎屑岩为主。层系上,油气主要富集于二叠系、石炭系和奥陶系,白云岩和生物礁储集层占重要地位。埋深上,储量分布相对集中的埋深为2500-3000m、3500-4000m和4000-4500m,分别占总储量的52.6%、15.9%和9.5%。油气藏类型上,以构造圈闭为主,不过近年来发现的大油气田的非构造圈闭比例有所增大。建议中国古生界海相油气勘探应重视白云岩储集层,更重要的是,应加强深层海相碳酸盐岩层系油气成藏机理和分布主控因素的研究。

Exploration for petroleum in the Paleozoic marine carbonate rocks is of great significance to China＇s energy security. Based on the analysis of the newest data for oil-gas fields, this study attempts to document the geological features and distribution patterns of giant marine carbonate rock oil-gas fields in the Paleozoie throughout the world. A total of 89 giant marine carbonate rock oil-gas fields in the Paleozoic had been discovered in 15 basins in the world by the end of 2013. Recoverable oil and gas reserves in these giant fields amount to 495.9×10^8 t oil equivalent, which make up 20.9% of the total recoverable reserves in all marine carbonate rock fields in the world. Results show that giant oil-gas fields mainly occur in the Middle East, former Soviet Union, North America and Asia Pacific, of which, giant oilfields are mainly distributed in former Soviet Union and North America, while giant gas fields are mainly confined to the Middle East and Asia Pacific. The peak discovery of giant gas fields occurred in 1970s. Oil and gas in the giant oil-gas fields were largely derived from the Paleozoic source rocks. In terms of relative importance, the most important source intervals are the Silurian, Carboniferous, Permian and Devonian. The source rocks are dominated by mudstones and shales, bituminous mudstones and shales and bituminous carbonate rocks. Evaporites and elastic rocks are the dominant seal rock. Stratigraphically, the reserves are concen- trated in three stratigraphic units： the Permian, Carboniferous and Ordovician. Dolostone and reef reser- voirs are of particular significance. The petroleum reserves are largely accumulated in three stratigraphic u- nits of burial depths： 2500- 3000 m （hosting 52.6% of the total） , 3500-4000 m （15.9%） , and 4000-4500 m （9.5%）. Structural traps are the main trap types for the giant oil-gas fields, but the proportion of non-structural traps has increased for the newly discovered giant oil-gas fields. For marine hydro- carbon exploration in China, it is suggested that a greater attention should be paid to dolostone reservoirs. More importantly, the studies of hydrocarbon accumulation mechanism and controlling factors for hydrocar- bon distribution in deep marine carbonate strata should be strengthened.