沉积盆地异常低压(负压)与油气分布

在沉积盆地油气勘探过程中,异常压力与油气聚集的关系愈显密切,而异常压力不仅仅是指异常高压,国内外在发现许多异常高压油气藏的同时,也发现了相当数量的异常低压油气藏,而且异常低压在世界许多盆地中均有分布.因此,深入研究异常低压的形成机理及与油气分布的关系,同样重要和不容忽视.本文介绍了异常低压的概念、特征和分类,详细分析了异常低压的形成机制:地层剥蚀卸载后的弹性回返(反弹)作用、流体的供排不平衡、轻烃的扩散作用、断裂和不整合面的压力释放作用、渗透作用和温度变化等;最后论述了异常低压与油气分布的关系.

The Anomalous Low Pressure (Negative Pressure) and Hydrocarbon Accumulation in a Sedimentary Basin

With the development of petroleum exploration, many abnormal overpressure fields and negative pressure fields were found in the world. The negative pressure and hydrocarbon accumulation are quite important in oil and gas exploration. In this paper, the authors describe the basic concept, features and classification of negative pressure and discuss in detail its formation mechanism, which includes rebound with uplifting and erosion, low recharge rates of liquid, diffusion of unstable hydrocarbon, pressure release of the fault and surface unconformity, permeable strata and decrease of temperature. The mechanism of negative pressure in oil-and gas-bearing basins and the relationship between negative pressure and hydrocarbon accumulation are also discussed. The formation of negative pressure compartments controls petroleum migration and accumulation. The negative pressure system indicates that the oil and gas pools are secondary. It opens a new exploration field for secondary oil and gas reservoirs and deep basin gas in the sedimentary basin.