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对井壁剪切破坏崩落规律的研究发现,井壁崩落扇形区域面积不受多次崩落影响,基本为定值,可通过4臂或6臂井径测井获取。以此规律为基础,基于线弹性理论,建立了井壁发生初次破坏崩落的数学模型。利用该模型,在已知最小水平主应力、岩石内摩擦角、内聚力、地层孔隙压力、钻井液柱压力和井壁崩落扇形区域面积一定的条件下,可反算出最大水平主应力。研究表明,模型计算结果与室内实验值十分接近,该模型简单实用、精度较高。
The study on the law of collapse and collapse in the borehole wall found that the area of the fanned wall in the borehole wall is not affected by multiple subsidence and is basically a fixed value and can be obtained by 4-well or 6-arm caliper logging. Based on this law, based on the linear elasticity theory, a mathematical model of primary collapse caving in wellbore wall was established. By using this model, the maximum horizontal principal stress can be calculated with known minimum horizontal principal stress, rock internal friction angle, cohesion, pore pressure, drilling fluid column pressure and the area of fan-shaped wall area. The results show that the model calculation results are very close to the experimental values in the laboratory. The model is simple and practical with high precision.