Research On The Broken Down Formula And Process Of Polymer Flooding Producing Well Of Sucker Rod Down Lag

Polymer flooding technology has been widely applied in Daqing oilfield, and it has made a significant effect. At the same time, however, many problems have been brought in the process of enhancing oil recovery and efficiently improving oilfield production. One of the most obvious problems is that the concentration of polymer in the produced liquid increases significantly compared with that in water flooding. Also, as produced liquid which contains polymer has a property of viscoelasticity belonging to non-newtonian fluid, the resistance has largely increased, which can lead to lagging or even eccentric wear or rod fracture in the downward movement of oil-sucking rod which can shorten the pump inspection cycle,affecting the normal production of polymer flooding. But nowadays, the field on broken down of extraction well as a real problem has been studied less. Most oil fields manage to maintain production applying several methods such as hot wash, scraping, ultrasonic instead of considering it from the angle of chemical broken down.To deal with the problem above, the composition of scaling samples on the wall of extraction well, the properties and the composition of produced liquid in Daqing oilfield were totally analysed. And the effect of rheology and viscoelasticity of produced fluid on oil-sucking rod has also been studied, on the basis of which, the blockage remover agent formula which is able to meet the actual requirements was developed indoors. The formula contains the main agent(oxidant, compound acid) and additives(ferric ion stabilizer, cationic copolymer and corrosion inhibitor). The descaling effect is optimal with a relatively weak corrosion on the rod when the concentration of oxidant is 3%, while the mass concentration ratio of amino sulfonic acid and hydrochloric acid in the compound is 4:1; Blockage remover agent additives were screened and developed: iron ion stabilizer(1% acetic acid), low poly cationic copolymer(0.4%) and inhibitor(0.1%), which has a high viscosity reduction rate of80% towards polymer gel, and a scale removal rate of more than 55%. Components contained in the blockage remover agent have compatibility with each other, and the corrosion rate on iron sheet is less than 1 mm/s, and has a relatively stable property. The permeability recovery rate in the experiment of core flow is above 75%. Indoor developed plugging agent solution has been applied on site and the lagging of oil-sucker rod downward movement has disappeared indoors when the developed blockage remover agent is applied on site.