Influence of Different Types of Formation Waters on Disintegration of Cements

Abstract

Abstract A study of the effect of various corrosive waters on five different types ofcements indicated that those cements containing less than 5 per cent tricalciumaluminate were the most resistant to corrosion. Introduction Oil field experience indicates that some formation waters are excessivelycorrosive to some cements. A study has been made to determine the mostcorrosive waters and the relative resistance of various types of cement tothese corrosive waters. Procedure This study of the corrosion of cement was limited to an evaluation of theeffect of various corrosive waters on five different types of cements. Adetermination was made of the types of cements which offer the greatestresistance to corrosion and of the chemical contents of waters found to be themost destructive to cements. The laboratory tests were conducted by immersing small cylinders of 20 samplesof set cement in various corrosive waters. The initial mixing of most of thecement slurries was done using Tulsa tap water as the mixing water; however, afew of the slurries were mixed using a sulfate water as the mixing water. Whenthe 20 samples had been immersed for a period of nine months, they were removedfrom their corrosive baths, inspected and photographed. The field tests were conducted by placing ten cement specimens, each containedin a screen wire thimble, in the gas anchors of insert pumps in wells in sixdifferent fields. The specimens were observed whenever it was necessary to pullthe pumps and were returned to the laboratory when deterioration had reached aserious state. Experimental Results In both the field and laboratory tests the resistance of the different cementsto corrosion was determined by the condition of the samples and the number ofsamples of each that were in good condition at the end of the immersion period.Table I lists the various cements tested in the order of their resistance tocorrosion with the most resistant at the top and the least resistance at thebottom. T.N. 59