伊拉克M油田防砂筛管堵塞物分析及解堵技术研究应用

Analysis of Oil Sand Screen Blockage in M Oilfield in Iraq and Blockage Removal Techniques

摘要: 伊拉克M油田井下筛管出现了较为严重的作业后堵塞问题，严重影响了油井正常生产，针对这一问题，鉴定了油井堵塞物类型并研制了一种油包酸型中间相解堵剂。首先，对M油田的储层特征进行了全面的分析，了解其潜在的油井堵塞可能，得出温压系统改变导致有机垢沉积和CO2、H2S腐蚀剥落铁锈的可能堵塞原因。然后，根据XRF等大型仪器分析结果，确定了有机堵塞物的主体为沥青质，无机堵塞物的主体为氧化铁，碳酸钙以及硫化亚铁，最后，通过多种酸液体系的溶解实验，进一步确认了堵塞物的类型，并优选出一种油包酸型中间相解堵配方体系和与之相适应的缓蚀剂体系，具备同时溶蚀有机垢和无机垢的复合解堵能力，并用模拟垢样对其进行了溶解验证实验。结果表明，该中间相酸解堵液体系在90℃条件下，对油套管的N80钢片无溶蚀作用，而2 h内对模拟垢样有着超过73%的溶蚀率，达到既能保护油套管而又能溶蚀堵塞物的目的，显示出良好的解堵效率。该解堵液体系，加入DCA-6缓蚀剂后，腐蚀速率大幅降低，超过行业的一级标准。该体系具备较强的缓速性能，可以达到缓速深部酸化的效果。

Abstract: Blockage of sand screen was found in the down hole of M oilfield of Iraq, which seriously affected the well production. To solve this problem, the type of the blockage was identified by XRD instrument, and a high efficiency single-phase microemulsion formulation was developed to solve the problem. After identifying the composition of the blockage, the reservoir characteristics of the M oilfield were analyzed to ascertain the potential reasons of the blockage. It was found that the potential reason of organic scale is high asphaltene content in crude oil, the potential reasons of inorganic scale are the peeling iron rust by H2S & CO2 corrosion, calcium carbonate precipitate from formation water, sand particles flowing from formation, which causes the well blocking. Then using XRF instrument, the main component of the organic scale was asphaltene, and the main components of inorganic scale were iron oxide, calcium carbonate and ferrous sulfide. Finally, by dissolving the scale in various acid solutions, the type of the scale was further confirmed. A blockage removing fluid, made up of an optimized W/O blockage removal fluid, and a corrosion inhibitor fluid, were developed and tested organic and inorganic scale solubility by simulated scale sample. It was found that the blockage removing fluid thermal stability is well at 90˚C and has no harm to the N80 coupon. The dissolved ratio of the simulated scale sample is over 73% in 2 h. This blockage removing fluid can not only protect casing & sand screen, also can dissolve the blockage, and it shows excellent blockage removing abilities. After adding a corrosion inhibitor DCA-6, its corrosion rate reduces dramatically, which exceeds the Class 1 of corrosion industrial standard requirement. The blockage removal fluid has strong retardance ability on acid-rock reaction, which is beneficial for deep penetration acidizing.