李艳, 赵均海, 李楠, 王娟, 吴赛. 基于统一强度理论的厚壁套管柱三轴抗拉强度[J]. 工程力学, 2015, 32(1): 234-240. DOI: 10.6052/j.issn.1000-4750.2013.07.0646
引用本文: 李艳, 赵均海, 李楠, 王娟, 吴赛. 基于统一强度理论的厚壁套管柱三轴抗拉强度[J]. 工程力学, 2015, 32(1): 234-240. DOI: 10.6052/j.issn.1000-4750.2013.07.0646
LI Yan, ZHAO Jun-hai, LI Nan, WANG Juan, WU Sai. TRI-AXIAL TENSION STRENGTH OF THICK-WALLED CASING STRINGS BASED ON UNIFIED STRENGTH THEORY[J]. Engineering Mechanics, 2015, 32(1): 234-240. DOI: 10.6052/j.issn.1000-4750.2013.07.0646
Citation: LI Yan, ZHAO Jun-hai, LI Nan, WANG Juan, WU Sai. TRI-AXIAL TENSION STRENGTH OF THICK-WALLED CASING STRINGS BASED ON UNIFIED STRENGTH THEORY[J]. Engineering Mechanics, 2015, 32(1): 234-240. DOI: 10.6052/j.issn.1000-4750.2013.07.0646

基于统一强度理论的厚壁套管柱三轴抗拉强度

TRI-AXIAL TENSION STRENGTH OF THICK-WALLED CASING STRINGS BASED ON UNIFIED STRENGTH THEORY

  • 摘要: 为了研究油气井厚壁套管柱的力学性能,基于统一强度理论,合理考虑中间主应力和材料拉压比的影响,推导了厚壁套管柱三轴抗拉强度的计算公式,分析了内外压比、材料的拉压比、中间主应力和径厚比等因素对不同工况下套管柱三轴抗拉强度的影响特性。研究结果表明:强度准则的选用对套管柱的三轴抗拉强度具有显著影响;材料拉压强度不等特性(SD效应)对套管柱的三轴抗拉强度也具有显著影响,当内外压比小于或等于1时,套管柱的三轴抗拉强度随材料拉压比的增大近似线性提高,当内外压比大于1时,材料SD效应的影响与外荷载有关;考虑中间主应力效应可以充分发挥材料的自承载能力和强度潜能,提高套管柱的三轴抗拉强度,具有一定的经济效益;内外压比和径厚比对套管柱的三轴抗拉强度也具有一定的影响。该文计算公式适用于具有SD效应和中间主应力效应的材料,并将多种屈服准则下套管柱三轴抗拉强度的表达式统一起来,具有广泛的适用性,可为油气井厚壁套管柱的设计提供借鉴。

     

    Abstract: In order to study mechanical properties of thick walled casing strings in oil and gas wells, a computational formula for the tri-axial tension strength of thick walled casing strings is deduced according to unified strength theory, considering the impacts of the intermediate principal stress effect and tension/compression ratio of materials. In addition, the influences of various factors on the tri-axial tension strength of casing strings under different load conditions are analyzed, including the internal pressure/external pressure ratio, tension/compression ratio, intermediate principal stress, and diameter/thickness ratio. The results show that the strength criterion has a significant influence on the tri-axial tension strength of casing strings. The strength disparity (SD) effect of materials also has a conspicuous impact on tri-axial tension strength. The tri-axial tension strength increases almost linearly with the growth of tension/compression ratios if the internal pressure/external pressure ratio is less than or equal to 1, while the influence of the SD effect of materials is related to loads when the internal pressure/external pressure ratio is more than 1. By considering the intermediate principal stress effect, full use can be made of the self-bearing capacity and strength potential of materials, so as to improve the tri-axial tension strength of casing strings and to bring certain benefits. The internal pressure/external pressure ratio and diameter/thickness ratio also have certain influences on the tri-axial tension strength of casing strings. The applicability of the proposed computational formula is broader and has unified the various expressions for the tri-axial tension strength of casing strings by using different yield criteria. Therefore, it is suitable for all kinds of materials which have both SD and intermediate principal stress effects, and it will assist greatly in the design of thick walled casing strings in oil and gas wells.

     

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