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为了研究孔隙对白云岩力学特性的影响,从四川某地露头和深度大于5000m的深部白云岩地层进行了取样,系统地研究了孔隙对白云岩的力学特性的影响。孔隙度是石油或天然气白云岩储层的重要特征之一。白云岩的试样孔隙度变化范围在6%～12%之间。在实验室对白云岩进行了单轴抗压强度试验、巴西劈裂法抗拉强度试验、直剪试验和三轴抗压强度试验。单轴抗压强度试验结果表明,岩石中孔隙度越高,岩石强度就越低。在不同围压作用下的多轴试验结果表明,在某一围压作用下,岩石的强度随着孔隙度的增加而减少;在相同孔隙度的岩石,应力偏量(三轴峰值应力)随着围压的增加而增加。介绍了孔隙岩石的MSDPu屈服本构模型,结果显示该模型能够较好地描述孔隙岩石的屈服特性。
In order to study the influence of porosity on the mechanical properties of dolomite, sampling was carried out from a deep dolomite formation with an outcrop depth of more than 5000 m in Sichuan Province. The effect of porosity on the mechanical properties of dolomite was studied systematically. Porosity is one of the key features of oil or gas dolomite reservoirs. The dolomite sample porosity ranged from 6% to 12%. Dolomites in the laboratory were uniaxial compressive strength test, Brazil splitting tensile strength test, direct shear test and triaxial compression strength test. The uniaxial compressive strength test results show that the higher the porosity in the rock, the lower the rock strength. The results of multi-axial tests under different confining pressures show that the rock strength decreases with the increase of porosity under a certain confining pressure. With the rock of the same porosity, the stress offset (triaxial peak stress) The confining pressure increases. The MSDPu yield constitutive model of porous rock is introduced. The results show that this model can well describe the yield characteristics of porous rock.