average the dichromate solution injection volume was 78 of the thief zone volume and the polymer volume was 27 of the thief zone volume the appearance of a small amount of a chrome 3 precipitate in one of the producing wells proved that the chrome was being reduced in the reservoir and the chrome was being propagated through the reservoir before it was reduced and made only slightly soluble there was a 40 reduction in water production from the two producing wells an injection well in the caddo limestone formation at a depth of 3200 foot and a temperature of 115 u00b0 f was treated with the redox gel process of this invention following a preflush with fresh water a slug of 7420 barrels of water containing 450 ppm sodium dichromate was injected over seven days then a spacer consisting of 3430 barrels of fresh water was injected and followed by a 6930 barrel slug of water containing 4730 ppm of nalco chemical company idf 193a emulsion polyacrylamide the molecular weight of this polymer was from 3 million to 5 million and its degree of hydrolysis was less than 1 per cent the polymer solution was injected for seven days during injection the pressure increased only slightly at the injection well so the well was shut in for four days to allow for additional gelation of the polymer to occur in the reservoir in an offset production well water production decreased from 2400 barrels per day to only 1150 barrels per day when the injection well was shut in this water production decrease was sustained for more than 10 months even though water.