基于振动参数的钻井井架安全承载力评定

通过井架结构振动理论、有限元分析和实验室简易模型的试验研究，提出了以振动频率为基准，载荷下降系数为依据诊断钻井井架结构安全承载能力的方法。根据井架的具体结构形式和受力特征，将井架简化成一根沿长度上质量均匀分布、刚度恒定的简支梁，用振动理论推导出了井架固有频率的平方与作用载荷之间存在着线性关系，并通过有限元分析对这一关系进行了验证；提出了通过测试井架在两种不同栽荷作用下的固有频率推算井架临界承载并以此评定井架安全承载能力的方法；在实验室内制作了与A型井架相类似的模型，进行了逐级载荷下的固有频率测试，分析总结出适用于井架现场评定的具体方法，最后应用此方法对现场在役井架进行了测试与安全承载能力评定。该评定方法为井架测试、安全评定提供了一个新的发展方向，对保证钻井安全将起到重要的作用。

Safety Bearing Capacity Evaluation for Drilling Derrick Based on Vibration Parameters

To evaluate the safety bearing capacity of drilling derrick, a novel method is proposed based on frequency and load descending coefficient by the research of vibraton theory, finite element model and experimental analysis of simple model of drilling derrick. According to the style and load characteristic of the drilling derrick, it is simplified to freely supported beam, which is uniform in mass and stiffness along altitude. The linear relations between the second power of frequency and acting load are researched on the basis of vibration theory, and the relations are verified through finite element model analysis. And then, the safety bearing capacity is deduced from the critical load calculated from the two natural frequencies. The similar model as A-shaped drilling derrick is built, and the grading load test is carried out on it. The evaluation method applicable for field engineering is concluded. At last, the safety bearing capacity of oilfield drilling derrick is obtained through load test. The method offers a new development direction for drilling test and safety evaluation, and also plays important part for safety drilling production.