沉积条件和埋藏过程对深层地层超压的影响

Effect of Sedimentary Conditions and Burial Process on Layers Overpressure in Deep Zones

针对沉积条件和埋藏过程对深层地层超压影响缺乏定量化的认识问题,通过构建反映不同沉积条件和不同埋藏过程的地质模型,运用盆地模拟软件数值模拟了不同岩性组合、不同上覆盖层厚度、不同埋藏方式和不同沉积速率条件下深层不同岩性地层超压的分布,并定量分析总结了沉积条件和埋藏过程对深层地层超压的影响。结果表明,随着沉积速率和上覆盖层厚度的各自增大,深层地层中形成的超压强度都会随之增大,并且这种增大作用在深层泥岩中比在深层砂岩中稍大;随着地层中泥岩含量的增大,深层地层中形成的超压强度也会随之增大,相比沉积速率和上覆盖层厚度,地层中泥岩含量的增大引起的深层地层中超压强度的增大作用更为明显;地层埋藏方式的改变可不同程度地引起深层地层中超压强度的改变,这种超压强度的大小改变规律在深层砂岩和泥岩之间、深层不同埋深泥岩之间不一定具有一致性,这与不同埋藏方式下地层中超压的形成同时受到多种演变规律不同因素的叠加效应有关。该研究可为深化认识深层地层超压的形成机制提供重要依据。

In order to deal with the problem of lacking quantitative analysis about the effect of sedimentary conditions and burial process on layers overpressure in deep zones,the geology models of different sedimentary conditions and different burial progress has been established in this paper.And then,the numerical simulation about the overpressure distribution of different lithology layers on the conditions of different lithological associations,different thicknesses of overlying cap rock,different burial ways and different sedimentary velocities have been used to quantitatively analyze and summary the effect of sedimentary conditions and burial process on layers overpressure in deep zones.The results show that the overpressure magnitude in the layers become bigger with the increase of sedimentary velocity and overlying cap rock depth,and this increase effect in the mudstones are higher than that in the sandstones.The overpressure magnitude in the layers also become bigger as the mudstone content in the layer becomes bigger,and the increase effect of overpressure in the layers due to the increase of mudstone content in the layer are more obvious than that caused by the increase of sedimentary velocity and overlying cap rock depth.The changes of burial way can cause the change of overpressure in the deep layers,and this changing rule is not necessarily consistent between sandstone and mudstone or between the mudstones of different depths,which relates with the superimposed effect of multi-factors,having different effect rules on the overpressure in the layer under the conditions of different burial ways.This study may supply the important evidence for deepening the understanding of genetic mechanism of overpressure in the deep zones.