基于EDTA解除电潜泵堵塞在鲁迈拉油田的应用

The Application of Unblocking ESP Based on EDTA in Rumaila Oilfield

针对鲁迈拉油田许多新电潜泵在试运行期间或其后不久即发生因硫酸盐结垢导致电潜泵卡泵的问题,开展了结垢样品实验室分析,进而通过化学品优选,确定了EDTA是溶解该硫酸盐结垢的最佳化学品,并在国内外首次对应用EDTA解除电潜泵堵塞的原理、作业步骤及注意事项进行了介绍,为将该技术应用在其他油田解决类似问题提供了参考。研究发现,井下硫酸钙的主要来源是储层产出水,而不是来自修井机安装新电潜泵时所使用的含有高硫酸盐组分的盐水。硫酸钙沉积物形成可能的原因是当电潜泵在运行时,电潜泵马达附近的温度远远高于井筒内电潜泵周围流体的温度,而电潜泵马达附近的高温、高压环境可能导致地层流体中的硫酸钙开始沉积在电潜泵的吸入口附近,日积月累最终导致电潜泵出现卡泵现象。

In response to the problem that many new electric submersible pumps （ESP） have been found plugged dur ing or shortly after the commissioning in Rumaila oilfield, it is determined by the laboratory analysis of the scales samples that it is the accumulation of calcium sulphate （CaSO4） that have caused the ESPs plugged. Furthermore, through chemical preference, it was determined that the EDTA is the best chemical to dissolve the sulphate scale. This paper introduces the principle, the operation steps, and the operation precautions of using EDTA to dissolve the plugged ESP and provides a technical reference for solving the similar problems in other oilfields. The study found that the main source of downhole calcium sulphate （CaSO4） was from the reservoir produced water, rather than the brine used during the installation of new ESP by workover operation. The possible cause of the formation of calcium sulfate scales is that when the ESP is in operation, the temperature near the ESP motor is far higher than the down hole temperature of the fluid around the ESP, and the high temperature and high pressure environment near the ESP motor may cause the calcium sulfate in the formation fluid to begin to deposit and accumulate near the intake of ESP which eventually caused the ESP plugged.