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

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