井下暂堵工具用可溶镁合金研究

发布时间：2018-11-28 18:23

【摘要】：我国近几年探明的油气储量中,70%是低渗透非常规油气资源,且低渗透非常规油气资源在未来我国油气产量中所占的比重还将进一步增长,这对我国油气产能的稳定增长具有重要的影响。开发这些非常规油气资源必须依靠水力压裂和酸压等储层改造技术,其中采用套管滑套、裸眼封隔器以及桥塞的多层多段压裂是目前的常用技术。井下分层分段压裂过程中,层段间需要投球或下桥塞进行封隔,再进行下一步施工,待施工完成后,需将此类暂堵工具去除。在井下暂堵工具中引入可降解材料,让工件在井下自行溶解失效,可以省去钻磨和回收工序,降低工程风险,提高施工效率,同时也可避免钻屑及循环液对储层造成伤害。因此,井下暂堵工具用高强度可降解材料的研发可实现提效和环保双赢模式,大幅提高作业效率,降低作业成本。镁合金材料的强塑性、刚度和加工性能都要远优于可降解高分子材料,并且可以通过成分调节、热处理、塑性变形、表面处理等方法对其降解速率进行有效调控。本文在Mg-Zn-Ca合金的基础上,添加Ni和Cu元素制备井下暂堵工具可降解压裂球材料Mg-Zn-Ca-Ni-Cu合金,使用EDS能谱仪对其元素及成分含量进行分析,研究合金元素在Mg基体中的分布规律。通过对铸态Mg-Zn-Ca-Ni-Cu合金进行热处理和热挤压变形处理,测试不同状态下合金的力学性能和腐蚀性能,研究不同加工状态对Mg-Zn-Ca-Ni-Cu合金的力学性能及腐蚀性能的影响规律,寻找合适的Mg-Zn-Ca-Ni-Cu合金生产加工工艺以满足井下暂堵工具可降解压裂球的使用要求。研究结果表明,Ni和Cu元素的添加对合金的力学行为的影响并不显著,但是会明显加速合金的高温/室温降解速率;热处理对合金的力学性能有较为明显的提升,但仍然无法满足井下暂堵工具可降解压裂球材料的技术指标;热挤压变形处理在显著提高Mg-Zn-Ca-Ni-Cu合金力学性能的同时,对合金的腐蚀降解速率也有一定程度的提升,经此处理后的合金满足井下暂堵工具可降解压裂球材料的技术指标,可以对压裂球进行试制并进入实际使用阶段。
[Abstract]:Of the proven oil and gas reserves in China in recent years, 70% are low permeability unconventional oil and gas resources, and the proportion of low permeability unconventional oil and gas resources in the future oil and gas production in China will further increase. This has an important impact on the steady growth of oil and gas production capacity in China. The development of these unconventional oil and gas resources must rely on hydraulic fracturing and acid fracturing and other reservoir reconstruction techniques, in which casing sliding sleeve, open-hole Packer and multi-layer and multi-section fracturing of bridge plug are commonly used at present. In the process of downhole stratification fracturing, it is necessary to seal off the layer by throwing ball or the lower bridge plug, and then to carry out the next construction. After the completion of the construction, the temporary plugging tool should be removed. By introducing degradable material into downhole temporary plugging tool, the workpiece can dissolve and fail by itself, which can save drilling and recovery process, reduce engineering risk, improve construction efficiency, and avoid damage to reservoir caused by drilling chip and circulating fluid at the same time. Therefore, the research and development of high strength biodegradable materials for underground temporary plugging tools can achieve a win-win mode of promoting efficiency and environmental protection, greatly improve the working efficiency and reduce the operating cost. The high plasticity, stiffness and processability of magnesium alloy are much better than those of degradable polymer, and the degradation rate of magnesium alloy can be effectively controlled by means of composition adjustment, heat treatment, plastic deformation, surface treatment and so on. In this paper, on the basis of Mg-Zn-Ca alloy, Ni and Cu elements are added to prepare Mg-Zn-Ca-Ni-Cu alloy, which can be used to degrade fracturing ball material in downhole temporary plugging tool. The elements and composition of Mg-Zn-Ca-Ni-Cu alloy are analyzed by EDS spectrometer. The distribution of alloying elements in Mg matrix was studied. The mechanical and corrosion properties of as-cast Mg-Zn-Ca-Ni-Cu alloy were tested by heat treatment and hot extrusion deformation. The effects of different working conditions on the mechanical properties and corrosion properties of Mg-Zn-Ca-Ni-Cu alloys were studied. To find suitable Mg-Zn-Ca-Ni-Cu alloy production and processing technology to meet the requirements of downhole temporary plugging tool biodegradable fracturing ball. The results show that the addition of Ni and Cu elements has no significant effect on the mechanical behavior of the alloy, but it can obviously accelerate the degradation rate of the alloy at high temperature / room temperature. Heat treatment can obviously improve the mechanical properties of the alloy, but it still can not meet the technical index of the downhole temporary plugging tool degradable fracturing ball material. The mechanical properties of Mg-Zn-Ca-Ni-Cu alloy were significantly improved by hot extrusion deformation treatment, and the corrosion degradation rate of the alloy was also improved to a certain extent. The treated alloy can meet the technical specifications of fracturing ball material degradable by downhole temporary plugging tool, and the fracturing ball can be trial-produced and entered the stage of practical application.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE93;TG146.22

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