Plug Removal Technology On The Well Injected By Waste Water With Polymer In Xing13Block

After the poly-containing sewage treatment system of Xing13station was put intooperation, the treated poly-containing sewage recycled to water wells of Xing13block. Withthe extending of polymer injection time, the scale expanded continuously, the poly-containingconcentration of recovery fluid gradually increased, sewage treatment equipment operatedbeyond its capacity. Because the treated sewage contained more polymer (averageconcentration was greater than130mg/L),at the same time, it contained a lot of oil, bacteria,sulfide and other impurities, when poly-containing sewage recycled to the formation, it mustpollute formation, reduce permeability of the reservoir. During the sewage recycling test, theinjection pressure often rapidly increased and the injection volume declined, application ofconventional acidizing and plugging removal technique, the effect was not good. So, iturgently need to carry on the test of plugging removal technique in poly-containing sewagereinjection wells.Based on the methods of chemical analysis, the test determined the composition of theflowback and analysed the plugging mechanismin in poly-containing reinjection wells;According to the reason of blockage in reinjection well, the test developed the degradationagent which contained oil displacement agent, surfactant and oxidant, this degradation agentcan be used as the plug remover; In order to improve the injectivity of the plug remover andprevent the deposition of pollutants in the pore surface, the test researched the wetting agentand anti blocking agent. In order to prevent the corrosion in wellbore and pipeline and thereact with the clay minerals of formation, during the injection process, we researched thecompound additive.The plugging removal agent can not only solve the plugging problem, but also canrelieve the polymer adsorption in the reservoir. All of these has great significance inimproving the development effect in Xing13block.