中国中西部类前陆盆地与典型前陆盆地类比rn及其油气勘探前景

摘要

中国中西部广泛发育中新生代类前陆盆地，其地质结构和石油地质条件等方面与典型前陆盆地既有类似之处也存在明显差异，主要表现在演化历史复杂：石炭纪以前均为构造性质各异的海相盆地，二叠纪为海相盆地向陆向盆地的转换过渡时期，三叠纪以后基本为陆相盆地（仅塔里木西南盆地晚白垩世—早第三纪有短暂海侵），侏罗纪—白垩纪为断陷-坳陷盆地（西部），第三纪以后，逐渐转变为类前陆盆地（西部）。在生烃条件方面不仅发育海相烃源岩，且普遍存在煤系烃源岩，进一步增加了其生烃潜力。同样，在储集条件方面，中国类前陆盆地除发育海相储集层外，还广泛分布陆相储集层。因此，中国类前陆盆地基本石油地质条件与国外富油气前陆盆地相比，除海相烃源岩的质量不及后者外，其它方面并无明显不足，且具有发育陆相烃源岩和储集岩的优势。因此，中国中西部类前陆盆地具有较好的勘探前景，特别是陆相层序具有更为现实的勘探价值。%There are some analogous foreland basins in central and west China, which are somewhat similar to and yet also obviously different from the typical foreland basins in geological structures and oil-gas conditions. The former basins have experienced complicated tectonic evolution. They were marine basins before Carboniferous, and evolved into continental basins after Triassic by transformation from the marine facies into the continental facies in Permian. The basins in west China were downfaulted depression basins in Jurassic and Cretaceous, and foreland basins in Cenozoic.These basins formed not only marine facies source rocks (oil type) and reservoirs but also continental facies source rocks (coal type and oil type) and reservoirs. The foreland basins in central and west China have more favorable oil-and gas-forming conditions than typical foreland basins and hence possess good petroleum exploration prospects.