用声波时差研究泥岩盖层毛细管封闭能力

Research of capillary seal ability and its formation period of mudstone caprock with acoustic transit time

Exploration Department, Daqing Petroleum Institute, Anda 151400, China

通过泥岩排替压力与孔隙度及孔隙度与声波时差之间关系的分析, 建立了泥岩排替压力与声波时差之间的定量函数关系。根据此关系, 利用声波时差可获得大量的排替压力信息, 据此不仅可以研究泥岩盖层毛细管封闭能力的剖面变化特征, 而且还可以研究泥岩盖层毛细管封闭能力的平面变化特征。通过泥岩排替压力与声波时差之间的函数关系, 利用声波时差资料较容易地确定泥岩盖层毛细管封闭能力形成时期, 结合烃源岩的大量排烃期可以判断泥岩盖层毛细管封闭油气的有效性。

A functional relation between mudstone replacement pressure and acoustic transit time is derived based on an analysis of the relationship between mudstone replacement pressure and porosity and the relationship between porosity and acoustic transit time.With the replacement pressure information obtained from the relation, the variability of capillary seal ability of mudstone caprock in section plane and in areal plane can be studied. The formation period of capillary seal ability of mudstone caprock can easily be determined with acoustic transit time according to the relation. Combined with the period that the source rock expels hydrocabon greatly, one can determine the effectiveness of mudstone caprock sealing for oil or gas. The actual results in Tarim Basin indicate that it is feasible to study the capillary seal ability of mudstone caprock and its formation period with acoustic transit time.