井眼附近地应力分布的三维数值模拟

该文研究的井眼附近地应力分布包括了钻井前、后两种截然不同的应力状态。以大庆外围某油田为例,用三维有限单元方法,施以适当的边界力,模拟计算出原地应力场,即钻井前地应力分布特征,其大小、方向均与中国东部实测应力场一致。在此基础上,根据井径a与井心距r同比例放大或缩小时应力计算结果不变的规律,采取了扩大井口半径的手段,计算钻井后井口附近的应力场变化特征,其规律与观测到的井眼崩落结果十分一致。 

NUMERICAL SIMULATION OF STRESS AROUND BORE HOLE

In this paper, the distribution of in-situ stress and the changed stress field after boring are studied. By use of three-dimensioal FEM and a adaptive boundary load, an outlying oil field of Daqing is modeled as an example. The results, including stress direction, the relationslip between stress and depth, are coincident with measured in-situ stress of East China. Then we get a rule that with the same ratio of radius and the distance from hole center, the calculated stresses are same. Based upon these, we enlarged hole radius and use 3-D FEM to calculate the stress around borehole. The changed stress field is coincident with the observed collapse of bore hole.