弯曲井眼内下部钻柱失效研究

为了揭示下部钻具失效的力学机理,章研究了下部钻具组合的弯矩和弯曲应力的分布规律。以结构力学中的染柱理论为基础,建立了带稳定器的下部钻具组合在弯曲井眼内的解析法力学模型。考虑到井眼有较大的造斜率,采用了与一般连续梁理论及三弯矩方程不同的方法。从基本力学模型出发,用静力法建立了下部钻具组合在弯曲井眼内的弹性线微分方程,合理设置力学模型的边界条件,得到下部钻具组合弯曲变形的弹性线方程,并导出了求解钻具任一截面弯短和弯曲应力的计算公式,编写了相应的计算机程序,计算了在一定工况下的下部钻具组合弯曲载荷的分布规律。

Research on Bha Failures in Curvature Hole

To find the failure mechanics mechanism of BHA, A thorough research on the stress distribution of BHA was done. In this paper, a analytic mechanics model of BHA in curvature hole was developed to find the bending moment or bending stress distributions feature based on the beam theory in structure mechanics. Considering higher rate of build - up, a different method unlike the co.analyzedcriticaloil, well, SBNDuan YQs good results in many oil and gas reservoirs. However, a lot of experiments indicate that fractured reservoir and low permeability reservoir are typical stress sensitive zone. The permeability decreases with decreasing of pore pressure and increasing of effective stress in oil field exploitation. So changes of permeability and porosity with stress should be considered in well test interpretation. According to results of experiment, this paper presented a mathematics model of fractured reservoirs with stress sensitivity and obtains type curves through by numerical Laplace inversion. This paper also discussed pressure transient and characteristics of type curves, and investigated stress impacting on buildup interpretation.