高温环境下铝合金钻杆磨损失效及防护机制研究

With the establishment of the global and unified concept of Earth System Science (go up to outer space, drill down into deep earth, go to sea and probe to poles), the scientific deep drilling or ultra-deep drilling that becomes an important means to “drill down into deep earth” is one important method for research of deep geology. Compared with the steel drill rod, aluminum alloy drill rod with its unique superiority (light weight, high specific strength, more deep drilling depth and less energy consumption) is as the essential scheme of the drill string design, which used in scientific ultra-deep well. However, the low hardness, the low anti-wear performance and the weak thermal stability are the main weaknesses of aluminum alloy drill pipe. It has greatly affected the application of aluminum alloy drill pipe under the high temperature condition of scientific ultra-deep well. Therefore, further knowledge of the wear failure and anti-wear protection mechanisms for the aluminum alloy drill pipe working under high temperature condition would be essential to scientific deep drilling and ultra-deep drilling engineering. In this proposal, based on the application of drilling， it is proposed that the wear behaviors of the aluminum alloy drill pipe in the wellbore are investigated, and the wear failure and anti-wear mechanisms are revealed and deeply discussed. It aims to build relationships among the wear failures, micro-structures, wear performances and anti-wear protection methods under the high temperature condition. The results would be expected that it would provide a theoretical and practical guidance to the application of aluminum alloy drill pipe technology under high temperature condition in the scientific deep drilling of the Songliao Basin.

随着全球性、统一性地球系统科学理念（上天、入地、下海、登极）的逐渐形成，作为“入地”重要手段的科学深井、超深井工程是研究深部地质学的重要方法，被誉为是“伸入地壳的望远镜”。与钢钻杆相比，铝合金钻杆以其独特的优越性(重量轻、比强度高、钻进深度深、所需能耗少)，已成为万米以深科学超深井钻柱设计的首要方案。然而，铝合金钻杆自身存在的硬度低、磨损性能差和热强性弱等问题，极大的影响了其在科学超深井施工中高温环境下的应用。因此，深入认知磨损失效及防护机制是高温环境下铝合金钻杆技术应用的核心与关键。本项目以铝合金钻杆应用为背景，通过磨损性能和防护方法实验的设计与实施，分析并建立铝合金钻杆的失效方式、组织结构、磨损性能、防护方法之间的关系，实现高温条件下铝合金钻杆与井筒磨损性能的理论预测与实验调控，为我国正在实施的“松辽盆地资源与环境深部钻探”工程提供基础实验数据和技术支撑。

铝合金钻杆自身存在的硬度低、磨损性能差和热强性弱等问题，极大的影响了其在科学超深井施工中高温环境下的应用。本课题通过25℃-160℃环境下磨损性能和防护方法实验的设计与实施，全面探索了铝合金钻杆的失效方式、组织结构、磨损性能、防护方法之间的关系。进行的钻柱与井壁摩擦碰撞机理分析，从动力学角度解释复合钻柱容易形成划痕、发生磨损的破坏原因，指导后续铝合金钻杆的磨损防护再制造工艺试验参数优化。对比研究的阳极氧化、微弧氧化、超声表面滚压以及复合涂层(微弧氧化/超声表面滚压)不同温度下摩擦学性能，试验结果表明：复合涂层性能最为优异，在超声表面滚压技术产生的具有大量晶格畸变和位错的塑性变形层上采用微弧氧化技术，再形成一个结构更为致密且具良好结合力的陶瓷膜层（膜厚25 μm），制备的复合硬质塑性变形层（膜厚350 μm）晶粒尺寸（纳米至微米）和硬度（120-425 HV）呈梯度变化，耐磨和耐腐蚀性大大提高。同时，未经处理与经表面强化处理的铝合金钻杆在松辽盆地资源与环境深部钻探“松科二井”、辽宁金羊盆地地质调查井“羊D1井”中进行了野外生产试验，试验结果表明：钻杆结构、碰撞与应力、钻井液介质、井内高温高压是其产生磨损与腐蚀的主要服役条件因素；经表面处理的铝合金钻杆相对于未经表面处理的铝合金钻杆具有较好的耐磨性，对钻杆进行有效防护，提高了其使用寿命。研究成果对我国未来的万米科学钻探工程的谋划与实施可提供基础实验数据和技术支撑。