极地钻探用铝合金双壁钻杆结构强度的有限元分析及试验研究

Finite element analysis and experimental study of aluminum alloy double-wall drill pipe for polar multi-process drilling

摘要:

为了实现钻穿冰盖、直接获取冰下基岩样品的科研目标，本文设计了一种极地钻探用铝合金双壁钻杆，使钻杆可以满足极地上覆积雪层、冰层、冰岩夹层和冰下基岩等不同地层的空气反循环、水力反循环、绳索取心钻进相配合等钻进需求。依据铝合金双壁钻杆在极限拉伸、极限拉扭组合工况下的受力情况，开展了双壁钻杆的有限元分析，并对双壁钻杆外管与钢接头连接试样进行了拉伸试验与扭转试验。双壁钻杆有限元分析结果表明：在极限拉伸和极限拉扭组合工况下铝合金双壁钻杆中产生的最大应力分别为183.8 MPa与161.9 MPa，均小于铝合金材料的屈服强度489.99 MPa。双壁钻杆外管与钢接头连接试样强度试验结果也表明：拉伸试样破坏时的极限可承载拉力为399.5 kN，远大于提升1000 m双壁钻杆所需的拉力（208.11 kN）；扭转试样破坏时的极限可承载扭矩为8264.7 N·m，同样大于钻杆在正常钻进过程当中所承受的最大扭矩（1990.56 N·m）。上述结果表明，极地钻探用铝合金双壁钻杆设计方案可以满足极地钻探使用要求。

关键词:极地钻探;铝合金双壁钻杆;结构设计;有限元分析;强度试验

Abstract:

In order to achieve the scientific research goal of drilling through the ice sheet and directly obtaining subglacial bedrock samples， this paper designs an aluminum alloy double-wall drill pipe for polar drilling， which can meet the drilling requirements of air reverse circulation， hydraulic reverse circulation， and matching with wire-line core drilling in different formations such as overlying snow layer， ice layer， ice-rock interlayer and subglacial bedrock on the polar region. According to the stress of aluminum alloy double-wall drill pipe under the condition of ultimate tensile and ultimate tensile torsion， the finite element analysis of double-wall drill pipe was carried out， and the tensile test and torsion test of the connection specimen between the outer pipe of the double-wall drill pipe and the steel joint were carried out. The finite element analysis results show that the maximum stresses generated in the aluminum alloy double-wall drill pipe under the combination of ultimate tensile and extreme tensile torsion conditions are 183.8MPa and 161.9MPa， respectively， which are less than the yield strength of 489.99MPa of aluminum alloy material. The test results of the specimen strength test of the connection between the outer pipe of the double-wall drill pipe and the steel joint also show that the ultimate bearing tensile force of the tensile specimen during failure is 399.5kN， which is much greater than the tensile force required to lift the 1000m double-wall drill pipe （208.11kN）； the limit bearable torque during torsional specimen failure is 8264.7N·m， which is also greater than the maximum torque of the drill pipe in the normal drilling process （1990.56N·m）. The above results show that the design scheme of aluminum alloy double-wall drill pipe for polar drilling can meet the requirements of polar drilling.

Key words:polar drilling;aluminum alloy double-wall drill pipe;structural design;finite element analysis;strength test