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.
Schematic layout and numerical model of a typical swellable packer showing elastomer element mounted on steel tubular, and rock formation or outer casing (above); Variation pattern of contact pressure as the elastomer swells under brine solution of low and high salinities for material-A (below). [Display omitted]
•Numerical simulation of swelling elastomer performance in oil-and-gas drilling and development.•Experimental investigation of swelling behavior and compressive and bulk properties of two swelling elastomers.•Swelling in salt-water solution of low and high salinity, at 50 °C temperature.•Prediction of sealing contact pressure under different conditions.•Results useful in performance evaluation and design improvement of elastomer seals.