Performance evaluation of swelling elastomer seals

Abstract

Swell packers are now being widely used for increased recovery from difficult oil and gas reservoirs and for remediation of various well problems. It is important to know how the elastomer actually swells in a particular well, how much time is required to achieve sealing, and what sealing pressure is generated. No published work is available that numerically investigates elastomer seal performance based on actual material properties at various stages of swelling. Current work uses finite element simulation to investigate swelling elastomer seal behavior in downhole petroleum applications. Variations in sealing pressure are studied for seal length, seal thickness, compression ratio, water salinity, swelling time, and type of well completion. Month-long swelling experiments on samples of two actual elastomers provide input to the numerical model in terms of real material and deformation data. Contact pressure was found to increase with swelling, at a higher rate in the first few days, then more slowly. Higher sealing pressure was observed in the case of swelling in lower-salinity brine, larger length of the sealing element, higher compression ratio of the seal, and elastomer swelling against rock formation as compared to steel outer-casing. These results can help field engineers decide which swelling elastomer and what seal configuration to use under a given set of field parameters. The study can also be used by application designers and academic researchers as a starting point for swelling elastomer based seal design and analysis.