We have developed a flush fluid for alkaline oxidation degradation of the mud cake for inhibited drilling fluid. The permeability of the smeary core when treated with the flush fluid increases by 125.6%. The mechanism of the washing process was studied by IR spectroscopy, scanning electron microscopy, and energy-dispersive x-ray spectrometry. The polymer backbone is broken down by the strong oxidant; the oligomers or even lower molecular weight fragments formed in this case are easily washed out.