气体钻井中钻柱失效试验研究

An Experimental Study of Drillstring Failure in Gas Drilling

为了研究气体钻井中钻柱在冲蚀和振动工况下的力学性能,通过使用新研制的能模拟气体钻井钻柱同时受到振动及冲蚀情况的试验装置,进行了不同钻具组合情况下钻柱力学性能试验和钻柱冲蚀试验。试验结果表明,气体钻井过程中,钻柱所受交变应力波在由底部钻柱向上传播时有一定的衰减,但衰减程度不大,所以下段钻柱的应力值对上段钻柱的受力有较大影响;钻柱绕井简反转将增大钻柱所受的交变应力,且转速越高交变应力变化越大,从而加深钻柱损伤程度;钻柱冲蚀量随着注气量的增大而增大,但其增大是非线性的。

To study the mechanical property of drillstring in gas drilling under the operating conditions of erosion and vibration,the newly-developed test unit which can simulate the drillstring in vibration and erosion at the same time was used to conduct the mechanical property test and erosion test of the drillstring with different bottomhole assemblies.The experimental findings show that in the process of gas drilling,there is a certain degree of attenuation when the alternate stress wave of the drillstring transmits upward from the drillstring bottom but the degree of attenuation is not remarkable.Therefore,the stress value of lower drillstring has remarkable effect on the force of upper drillstring.The counter revolution of drillstring around the wellbore will increase the alternate stress of the drillstring.The higher the rotation speed,the greater the alternate stress changes.As a result the damage to the drillstring will increase.The drillstring erosion amount increases with the increase of steam injection,but the increase curve is not linear.