American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.
One of the primary problems in designing cement systems for deep, hot wells is the wide variation in performance of oil well Portland cements. Thickening times between Portland cements. Thickening times between similar API cements may vary by more than 100 per cent under severe well conditions. To help minimizes this problem, a special computer program was used to compare the working time of eleven oil well cements with their chemical analyses. This resulted in the isolation of the chemical factors which have the greatest effect on cement thickening time at a particular set of conditions. The equations developed provide the capability to predict cement working times under specified well conditions when a few chemical parameters of the cement are known.
The trend toward deeper and hotter oil wells and the expanding search for geothermal energy has made it necessary to examine the performance of Portland Cement at higher performance of Portland Cement at higher temperatures and higher pressures. Under these conditions, slurry working times have not been as predictable as they are at lower temperatures and pressures.
Studies have been made which identify the compounds formed in set cement, and the physical and chemical conditions required to develop physical and chemical conditions required to develop stable compressive strengths at higher temperatures. However, very little has been done to define the parameters that determine the working time of retarded Portland Cement systems used in oil and gas wells. To help develop better high temperature retarders, and to explain fluctuations in existing data, the computer has been incorporated into high temperature cement testing. The results presented here show that not only can the computer be used to predict working times at various retarder concentrations, but it can also be used to define the parameters most important in determining the parameters most important in determining the working time of a particular cement system.
