Elastomer Testing in Sour Environments

Due to the increase in need for combustibles, in particular oil, sweet hydrocarbon reservoirs are fast becoming depleted. This has led to the need to tap into sour reservoirs. The presence of hydrogen sulfide (H₂S) in the reservoirs has presented new challenges to oil production companies. Among these challenges is determining the effect of H₂S on elastomeric seals used in oil production systems.
            This paper examines the effect of H₂S on both the mechanical and chemical properties of elastomers commonly used in the petrochemical industry^1,2. Autoclave exposures have been used to condition the elastomers in both artificial sea water and mixtures of hydrocarbons and H₂S environments at high temperatures and pressures. Mechanical properties (tensile strength, modulus, hardness, etc.) have been measured and compared to the mechanical properties of un-exposed samples. Samples exposed for a relatively short time under the severe conditions tend to absorb H₂S and increase in volume.
In addition to the chemical and mechanical analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and Fourier transform infrared spectroscopy (FTIR) have been utilized to examine the chemical effect of H₂S on the elastomeric samples.
References

1. H. A. Pfisterer, J. R. Dunn and R. Vukov, “The use of a screening test for assessing the hydrogen sulfide resistance of elastomers”, Rubber Chemistry and Technology, Vol. 56, p. 418-430.
   
2. T. C. Merkel, and L. G. Toy, “Comparison of Hydrogen Sulfide Transport Properties in Fluorinated and Nonfluorinated Polymers”, Macromolecules, 2006, 39 (22), p. 7591-7600.