Retarderingssystem for oljefelt-sementoppslemminger, sementoppslemminger og sementeringsprosess

摘要

The invention relates to the cementing of high temperature wells. The retarder consists of a methylene phosphonic acid derivative and of a boric acid or a borate at least as acid as borax in an aqueous solution, in particular Na pentaborate, in a preferred ratio of 0.08 to 0.92 parts by weight. A long setting time and very swift compressive strength development are obtained at the same time.