【摘要】 基于流变理论的数字、物理模拟以及生产实测数据分析均表明,异常流体压力条件下的应力莫尔圆在位移过程中存在直径(差异应力)的耦合变化,即最小水平应力自常压条件向超压条件逐渐增大。耦合规律显示,异常流体压力的保存明显受控于区域与局部异常流体压力间的差异性。厚层泥岩中流体压力的增高相对均一,区域性异常流体压力达到或超过垂向应力则易产生流化作用或水平张裂缝。倾斜砂岩顶点可存在较强的局部异常流体压力,该顶点处破裂压力会伴随区域流体压力的增高而增大,破裂压力可明显超过负载压力;且区域异常流体压力增高过程中的破裂方式(裂缝倾角)也存在明显变化。耦合机制下,异常流体压力的保存或泄放状态突破了传统预测值,也为相关异常地质过程成因探究和技术应用研究奠定了基础。更多还原

【Abstract】 Sediment rheology poroelasticity and digital/physical simulation have demonstrated that displacement and diameter(different stress)of Mohr circle are in fact coupled under abnormal fluid pressure condition.In brief,elevated fluid pressure(Pp)is associated with minimum horizontal stress(Sh).Sh/Ppcoupling process reveals that retention capacity affected by the difference between the regional and local fluid pressure.For regional fluid overpressure in relatively homogeneous mud rocks can reach or even exceed vertical stress,the stresses become tensile and the least principal stress becomes vertical,producing horizontal hydrofractures.For crests of inclined sand reservoirs,failure pressure at the crest is mainly controlled by the regional fluid pressure and it can be a greater than the overburden pressure.Increasing regional fluid pressure can change fracture dip and both horizontal and vertical fractures can be produced.Sh/Ppcoupling mechanism provides a more accurate way to predict abnormal fluid pressure retention or leakage condition,and laid a foundation for technology application and geological process causes.更多还原