超压对断层垂向封闭作用的定量研究

Quantitative research on effect of overpressure to vertical seal of fault

在断层垂向封闭机理及影响因素分析的基础上,通过地层有无超压存在时断层面压力大小和垂向封闭形成所需的最小埋深大小的对比研究得到,超压存在,断层面压力增大,垂向封闭性增强。但与超压值本身大小无关,仍受断层面埋深和倾角的影响,随断层面埋深增大,断层面倾角减小,断层垂向封闭性增强;反之则减弱。超压存在,断层形成垂向封闭所需的最小埋深变小,且随断层面倾角变小,断层垂向封闭形成所需的最小埋深变小;反之则变大。通过松辽盆地汪家屯气田W 1、W 2、W 3、W 4断层在青一段有超压存在时断层面压力和形成垂向封闭所需的最小埋深大小的对比研究,得到有无超压存在时断层面压力约为无超压存在时断层面压力的1.76倍,断层垂向封闭形成所需要的最小埋深明显减小,形成时期明显变早。

Based on the analysis of vertical seal mechanism of fault and its influence factors, by comparatively studying the pressure on fault surface and the minimum depth required in forming vertical seal of fault if there is or not overpressure in a stratum, it was considered that if there is overpressure in a stratum, the pressure on fault surface increases and the vertical seal increases. But it has nothing to do with the range of overpressure other than influenced by depth and tip angle of fault surface. With the increase of depth and the decrease of tip angle of fault surface, the increase degree of vertical seal of fault increase, on the contrary, the increase degree of vertical seal of fault decreases. If there is overpressure in strata, the minimum depth required in forming vertical seal of fault decreases, with the decrease of tip angle of fault surface, the minimum depth required in forming vertical seal of fault decreases, on the contrary, the minimum depth required in forming vertical seal of fault increases. By comparatively studying the pressure on fault surface and the minimum depth required in forming vertical seal of W1, W2, W3, W4 faults in K1 qn when there is or not overpressure in it, it was considered that the vertical seal of W1, W2, W3, W4 faults in K1qn when there is overpressure in it, it is as about 1.76 times as that when there is no overpressure in it. The minimum depth required in forming vertical seal of fault decreases obviously and formation time of fault seal becomes earlier.