中文摘要：

采用Kaiser效应测定深部地层地应力时，由于油藏岩芯不规则及试件制备过程的误差等因素存在，取样时的偏差会影响地应力测量。假定0°方位和90°方位的取样方位准确而45°方位取样存在一定偏差，根据弹性力学和级数展开建立了应力测量误差分析的力学模型。采用深层均质砂岩岩芯，并变化取心角度（偏差）进行一系列Kaiser效应试验，对比试验和小型压裂解释结果发现Kaiser岩样偏差对地应力数值确实存在影响，其关系为二次函数；当取样偏差角度在5°以内时，应力测试误差可以忽略不计；大于5°时引起的地应力解释误差不能忽略。对于非定向钻取的全尺寸岩芯，当参考取样方位不同时，取样偏差的影响幅度不同。对于深部地层的不规则岩芯，可根据所建立的模型对Kaiser效应测试结果进行相应的误差分析。

英文摘要：

Kaiser effect is widely used in geostress determination in petroleum industries, while other typical methods are restricted for great depth and complex wellbore conditions. During the measurements of geostresses at great depth with Kaiser effect, sampling deviation possibly has some effects on geostress due to irregular shapes of full-scale core and errors in preparing samples, which may be ignored by users and is not considered yet. Supposing that the sampling orientations of 0° and 90° are both accurate and there is some small deviation in the orientation of 45°, a simplified mechanical model is built up based on elasticity theory and series expansion. A series of experiments were conducted with homogeneous reservoir sandstone by changing the sampling deviations; and the comparisons between experimental results and mini-frac interpretations indicate that Kaiser sampling deviations have effects on geostress in quadric relations, which agrees well with the proposed model. When the sampling deviation angle is less than 5°, the effect can be neglected, but great deviation angles have significant influences that can not be neglected; and the changes of geostress are about 2.5 MPa when sampling deviation is 15°. The effect changes with different referenced angles in non-directional full-scale cores. As for irregular cores at great depth, it will be caused by mechanical damage and natural fractures; and it is impossible to get perfect three samples strictly in direction of 0°, 45° and 90 °, respectively. Thus the proposed model has its priority and can be used to evaluate the measurement errors of geostress.