时深效应指数影响因素分析

Analysis of influencing factors of time-depth index

时深效应指数TDI的计算受到多种因素影响,这些因素在一定程度上会制约实际应用效果。结合实际资料,分别针对TDI计算过程中的去压实恢复、压实系数与地表孔隙度的求取、超压和地层剥蚀恢复等因素,进行了不同计算条件下埋藏史演化曲线和TDI值的分析比较。结果表明:如果考虑压实作用的影响,将会使TDI值增大;如果考虑地层剥蚀的影响,将会使剥蚀前地层的TDI值增大;存在超压时地层的有效埋深比实际埋深小,因而考虑超压因素计算的TDI值将会有所减小,且其计算精度受反演的地震速度场的精度以及井点压力与速度间关系的可靠性的影响。

There are many influencing factors for calculation of time-depth index.These factors may restrict its application to some extent.In this paper,burial history evolution curve and TDI value have been calculated and compared with actual data considering such influencing factors as decompaction correction,compaction coefficient and initial surface porosity,recovering denudation and overpressure.It can be concluded that the TDI value will be increased while considering decompaction correction.The TDI value of sedimentary layers before the denudation stage will increase while considering recovering denudation.The effective buried depth is smaller than the actual depth in the overpressure environment,and the TDI value will decrease while considering overpressure.The accuracy of the results is affected by the inverted velocity field and the reliability of the relationship between the pressure at well position and velocity.