Study of the Plugging of Oil Well Sand Control Area in a Polymer Flooding Region

摘要

Study of the Plugging of Oil Well Sand Control Area in a Polymer Flooding Region — The plugging of the oil well sand control area in a polymer flooding region was studied and the plugging substances were analyzed through UV-Vis spectrophotometer analysis, plasma emission spectrometry analysis, laser particle size analysis, X-Ray Difjractometer (XRD) analysis, microscopic observation, chromatograph-mass spectrometer, etc. It is inferred that the main reason for the plugging of the sand control area was the adsorption, gathering and bridging of PAM on the surface of the sand. The migration of the mineral fines from the stratum and the adsorption of the crude oil ingredients on the surface of the fines also result in plugging. An experimental study on the polymer degradation was performed and two types of plug removal agents, potassium per sulfate and sodium thiosulfate, were selected and tested. It showed that potassium persulfate and sodium thiosulfate could degrade the plugging substances and recover core permeability effectively. Moreover, field application tests were conducted in Gudao oilfield which showed the restoration of the performance of various wells. It also indicated that the injection pressure obviously decreased and liquid production per day increased greatly after application of the plug removal agents in the sand control area.