油气成藏期探讨

An Approach to Hydrocarbon Accumulation Period

成藏期是一个时间段,一个油气藏由多次充注形成。烃包裹体的存在是油气运聚的直接证据,利用流体包裹体均一温度分布图所对应的时间可以确定出成藏期。均一温度直方图分为连续分布型和非连续分布型两类:前者表示连续性的充注一期成藏;后者表示非连续性的充注多期成藏。成藏期是成藏史研究的一部分,新生代油气的成藏史比较短,多为一期成藏;古生代油气的成藏史比较长,可能有多个成藏期。但古老油气藏大部分都已破坏消失,只有那些不断有油气充注或是晚期成藏的才能被保存下来,而目前它们未必具有多期成藏的特征,只有作成藏史研究才能对它们进行评价。

Petroleum accumulation period is a section of time. The formation of an oil/gas pool tends to being resulted from multiple charging. The presence of hydrocarbon inclusion is the direct evidence for oil-gas migration and accumulation. The petroleum accumulation period can be determined based on the time corresponding to fluid inclusion homogenization temperature which can be plotted by continuous and discontinuous distribution types of histograms. The continuous distribution type indicates continuous charging and just one-period accumulation. The discontinuous type means discontinuous charging and multi-period accumulations. In terms of accumulation history partly described by accumulation period, the Cenozoic petroleum accumulation history is relatively short, most belong to one-period accumulation, while Paleozoic petroleum accumulation history is comparatively long, and there could be multi-period accumulations. This paper suggests that most of paleo-oil/gas reservoirs is destroyed, only could those pools that are continuously charged with oil and gas or formed in late period preserve, but they may not necessarily be characterized by multi-period accumulations. Only by study of the accumulation or charging history can they be evaluated.