This paper presents initial results of a new testing program initiated to determine the performance of natural and man-made ceramic proppants over extended periods of time (months). The mechanisms involved in proppant performance are related to chemical and crystallographic makeup, as well as to processes used in their manufacture. Definition of the mechanisms controlling proppant behavior will allow future product development work to be concentrated on improving performance characteristics.
Data from standarized API permeability/ conductivity testing are presented with a summary of previous long term testing. Results are coupled with new long term permeability data and acid reactivity data. Chemical and crystal structure phase analyses are also reviewed. The various tests were performed on a variety of oxide ceramics (intermediate and high strength proppants) as well as quartz sand.
The long term data show that, after an initial period of consolidation, reductions in permeability over time are very slight for the commercial ceramic proppants tested at conditions of 69 MPa stress, 93°C, flowing a 2% KCl brine. Efforts made to correlate long term performance to short term acid reactivity have not been successful. It is unlikely that the long term performance of different classes of proppant can be compared by analyzing standard acid reactivity data.