| abstract |
We have found that it is possible to produce resin coated particular matter having uniform coating of resin to protect the particles against erosion or dissolution on contact with high pH fluids. The coated sand or other particles is produced by introducing the particles into a mixing device, to which is added a resin mixture comprising a urea formaldehyde resin and a furfural alcohol resin. The sand and resin mixture is mixed for sufficient time to accomplish uniform coating of the sand particle with the resin mixture. Next a foaming aqueous surfactant containing fluid is added which causes the resin-coated sand particles to be suspended in the foaming aqueous mixture. The surfactant fluid also contains acid catalyst. This mixture is allowed to set for a period of time after which the coated particles are washed and then cured at 300° C. to accomplsih drying and complete the polymerization reaction. Coated sand grains are highly resistant to prolonged contact with strong alkaline fluids such as are encountered in subterranean formations being stimulated by injection of hot alkaline fluids. |