含流体岩石弹性形变状态下的力学机制

Mechanical Mechanism of Rock with Fluids under Elastic Deformation

有效应力定理揭示了多孔弹性材料中多孔骨架与孔隙流体分担围压的力学机制,但是Terzahi的有效应力定理不能通过应变与应力的关系解释其理论的有效性。Biot和Willis的有效应力定理描述了饱和多孔岩石在孔隙压力保持不变的情况下岩石应变与应力的关系,不能解释饱和岩石孔隙压力随围压增加而增加的力学机制。本文从理论上推导了Biot和Willis的有效应力定理成立的条件及其有效性,根据Gassmann方程描述了饱和岩石围压增加所引起孔隙压力增加的这一力学机制,对孔隙压力预测及其应用提供了有力的理论依据,在石油勘探开发中具有重要的应用价值。

The effective stress theorem reveals that the mechanical mechanism of confining pressure is shared by the porous skeleton and pore fluid in porous elastic materials, but Terzahi’s effective stress theorem can not explain the validity of the theory by the relationship between strain and stress. Biot and Willis’ effective stress theorem describes the relationship between strain and stress of saturated porous rocks when pore pressure remains constant, but can not explain the mechanical mechanism of pore pressure increasing with confining pressure. In this paper, the establishment condition and validity of Biot and Willis’ effective stress theorems are deduced theoretically. According to Gassmann’s equation, the mechanical mechanism of pore pressure increase caused by the increase of confining pressure of saturated rock is described, which has important application value in petroleum exploration and exploitation.