Acta Petrolei Sinica ›› 2021, Vol. 42 ›› Issue (6): 791-800.DOI: 10.7623/syxb202106008

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A mechanism of expandable conductor used to improve the bearing capacity of subsea wellhead in deep-water drilling

Zhang Minghe1, Yang Jin1, Liu Hexing2, Li Lei1, Fu Chao1, Yang Yuxiang1, Xu Dongsheng1, Ma Kuo1   

  1. 1. College of Safety and Ocean Engineering, China University of Petroleum, Beijing 102249, China;
    2. Zhanjiang Branch, CNOOC China Limited, Guangdong Zhanjiang 524057, China
  • Received:2020-07-03 Revised:2020-12-16 Online:2021-06-25 Published:2021-07-06

膨胀式导管提高深水钻井水下井口承载力的机理

张明贺1, 杨进1, 刘和兴2, 李磊1, 傅超1, 杨宇翔1, 徐东升1, 马阔1   

  1. 1. 中国石油大学(北京)安全与海洋工程学院 北京 102249;
    2. 中海石油(中国)有限公司湛江分公司 广东湛江 524057
  • 通讯作者: 杨进,男,1966年3月生,1989年获石油大学(华东)学士学位,2004年获中国矿业大学(北京)博士学位,现为中国石油大学(北京)教授、博士生导师,主要从事石油工程和海洋工程领域的教学和科研工作。Email:yjin@cup.edu.cn
  • 作者简介:张明贺,男,1994年7月生,2018年获中国石油大学(北京)学士学位,现为中国石油大学(北京)博士研究生,主要从事海洋油气钻采方面的研究工作。Email:2018210018@student.cup.edu.cn
  • 基金资助:
    国家自然科学基金重点项目"海洋深水浅层钻井关键技术基础理论研究"(No.51434009)、国家自然科学基金创新研究群体项目"复杂油气井钻井与完井基础研究"(No.51221003)和国家自然基金面上项目"深水油气井导管全寿命周期承载力演化机理研究"(No.51774301)资助。

Abstract: Surface conductor is the main supporting structure of subsea wellheads in deep-water drilling. Complex accidents such as subsea wellhead instability and sinking are mainly caused by the insufficient bearing capacity of surface conductor. Therefore, the deep-water drilling engineering focuses on how to economically and efficiently increase the bearing capacity of surface conductor. The expandable conductor is used to improve the bearing capacity of surface conductor, after the conductor is installed at the projected depth of seafloor without changing the process conditions of installing the surface conductor by the conventional deep-water jetting method, the surface area of surface conductor in contact with the seafloor soil is increased due to the expansion of expandable material, thus enhancing the lateral friction of surface conductor and the bearing capacity of subsea wellhead. Based on the main structural composition of the subsea wellhead of deep water drilling, this paper analyzes the relationship between the size of surface conductor and the bearing capacity of subsea wellhead by establishing a calculation model for the bearing capacity of subsea wellhead in deep-water drilling, reveals the linear change between the external surface area of the expandable surface conductor and the bearing capacity of subsea wellhead, and obtains the calculation model between the thickness of expandable material and the bearing capacity of subsea wellhead. Moreover, this paper proposes that the segmented structure of expandable material can increase the bearing capacity of expandable conductor, and analyzes the influence laws of the number of sections, coverage area, and expansion thickness of expandable material on the bearing capacity of surface conductor. It is concluded that the bearing capacity of surface conductor increases linearly with the increase in the number of segments under the same coverage area, and the bearing capacity increases linearly with the increase in the expansion thickness. Through the application test of 3 deep-water wells in the South China Sea, the error between the results from the calculation model established for the drilling bearing capacity of subsea wellhead and those from the field test is about 5%.

Key words: deep-water drilling, subsea wellhead, expandable conductor, bearing capacity, wellhead stability

摘要: 表层导管是深水钻井水下井口的主要持力结构,水下井口失稳、下沉等复杂事故的发生主要是由于表层导管承载力不足造成的,因此经济高效地提高表层导管承载力是深水钻井工程研究并关注的重点。采用膨胀式导管方法来提高表层导管的承载力,能够实现不改变常规深水喷射法安装表层导管的工艺。表层导管喷射安装到海底设计深度后,膨胀材料发生膨胀实现增加表层导管与海底土接触的表面积,进而提高表层导管侧向摩擦力和水下井口承载力。基于深水钻井水下井口主要结构组成,通过建立深水钻井水下井口承载力计算模型,分析了表层导管尺寸与井口承载力相互关系,揭示了膨胀式表层导管外表面积与水下井口承载力呈线性变化规律,得出了膨胀材料厚度与水下井口承载力之间的计算模型;提出了膨胀材料采用分段式结构可以提高膨胀导管承载力,分析了膨胀材料分段数量、覆盖面积、膨胀厚度对表层导管承载力的影响规律;得出了在相同覆盖面积条件下随着分段数量增加表层导管承载力呈线性增加,随着膨胀厚度增加承载力呈线性增加。通过中国南海现场3口深水井的应用试验,建立的钻井水下井口承载力计算模型结果与现场试验结果的误差约为5 % 。

关键词: 深水钻井, 水下井口, 膨胀导管, 承载力, 井口稳定性

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