井筒橡胶材质腐蚀损伤及适用性评价研究

发布时间：2018-09-10 20:59

【摘要】：橡胶密封制品在油气开采作业中发挥着重要作用。随着油气开采的发展,其工作环境越发恶劣,而橡胶材质的工作性能与外界环境密切相关。在高温高压高含腐蚀性介质的工况下,橡胶材质会受到腐蚀损伤,导致橡胶密封制品工作性能下降,破坏井筒完整性,影响井下正常作业甚至引发安全问题。因此,研究橡胶材质在井筒环境中的腐蚀损伤及适用性具有重要意义。 本文首先针对以往橡胶材质实验研究未模拟井筒橡胶密封件工作环境和工作状态的不足,以O形圈为试样,自主设计了一种实现试样承压状态的密封组件装置和实现模拟井筒工况的高温高压动态釜装置。通过探究此实验方法的可行性,发现橡胶材质在模拟井筒工况下服役后,外貌受损,几何尺寸产生一定的变化,但是不能根据外形尺寸的变化准确判断橡胶材质的优劣,不建议将其作为橡胶材质腐蚀损伤和适用性评价的主要考察指标。而服役后,橡胶材质力学性能下降,其中,拉伸强度降低,拉断伸长率减小,硬度减小,压缩永久变形增大。力学性能对比性强,可靠度高,建议将其作为主要考察指标。 而后模拟某高含CO2天然气生产井井筒工况,在压力为35MPa、温度为140℃、CO2介质体积分数为5%,CH4体积分数为95%的条件下,对氟碳橡胶、氟硅橡胶、四丙氟橡胶和氢化丁腈橡胶四种橡胶材质的O型圈试样进行了高温高压腐蚀实验并对四种橡胶材质在此工况下的适用性作出了评价。实验结果显示,相比自由状态,承压状态下橡胶材质的腐蚀损伤程度较小,且自由状态下,橡胶材质的液相腐蚀较为严重,而承压状态下,则是气相腐蚀较为严重。因现场作业中,橡胶密封件通常处于承压状态,建议以承压状态下的性能考察试验结果作为橡胶密封件可靠性和材质适用性评估的主要参考依据。在此模拟工况下,氢化丁腈橡胶的适用性最优。此外,结合EDS分析和拉伸断口形貌分析,解释了橡胶材质在井筒环境中的腐蚀损伤机理和影响因素。研究发现,四种橡胶材质在此模拟工况下服役后,其拉伸断口以脆性断口为主。 最后,对四种橡胶材质进行了C02介质渗透性测试。以橡胶密封组件内碱性显像剂溶液的pH值变化考察了在C02含量一定时,四种橡胶材质的C02渗透性随环境温度和压力的变化。
[Abstract]:Rubber seal products play an important role in oil and gas exploitation. With the development of oil and gas exploitation, its working environment is more and more bad, and the working performance of rubber material is closely related to the external environment. Under the condition of high temperature and high pressure and high corrosive medium, the rubber material will be corroded, which will lead to the deterioration of the working performance of rubber sealing products, the destruction of wellbore integrity, the influence of normal operation and even the safety problems. Therefore, it is of great significance to study the corrosion damage and applicability of rubber material in wellbore environment. In this paper, first of all, in view of the shortcomings of the previous rubber material experiments, which did not simulate the working environment and working state of rubber seals in wellbore, the O-ring was taken as the sample. In this paper, a kind of sealing device is designed to realize the pressure state of the sample and a dynamic autoclave with high temperature and high pressure is designed to simulate the wellbore working condition. By exploring the feasibility of this experimental method, it is found that after the rubber material is in service under the simulated wellbore condition, the appearance is damaged and the geometric dimension changes to a certain extent, but the rubber material can not be judged accurately according to the change of the shape size. It is not recommended that it be used as the main index for evaluating the corrosion damage and applicability of rubber materials. After service, the mechanical properties of rubber decreased, including tensile strength decreased, elongation at break decreased, hardness decreased, compression permanent deformation increased. The mechanical property is relatively strong and the reliability is high. It is suggested that it should be regarded as the main inspection index. Then, under the condition that the pressure is 35 MPA, the temperature is 140 鈩，

本文编号：2235600