Study of hydrogen sulfide effect on acrylonitrile butadiene rubber/hydrogenated acrylonitrile butadiene rubber for sealing application in oil and gas industry

Acrylonitrile Butadiene Rubber (NBR) and Hydrogenated Acrylonitrile Butadiene Rubber (HNBR) have been widely used in many sealing applications for downhole operation. To build practical operation limits for NBR and HNBR packer elements, it is required to fill the gap between laboratory-scale tests and field operation experience on how packer elements behave in such conditions. This study encompassed the experimental work on NBR and HNBR packer elements exposed to various sour conditions comparable to field operation. The elastomer specimens, such as NBR, showed less resistant to H2S in the controlled laboratory tests (e.g., at 121 degrees C and 52.5 MPa with 5% of H2S) compared with an uncontrolled environment inside oil and gas well (e.g., at 134 degrees C and 47 MPa with 3.5% of H2S). The behavior could be explained by different exposure conditions like exposure geometry, stress, temperature, pressure, and H2S concentrations. This is potentially the first-ever comprehensive study in the oil and gas industry, which shows that the operation limit of NBR and HNBR packer elements can be extended to a higher H2S concentration.

Automated summary

This study compared the behavior of NBR and HNBR packer elements under different sour conditions through experimental tests. It was found that the packer elements showed lower resistance to H2S in the controlled laboratory tests compared to the uncontrolled environment inside oil and gas well, which can be attributed to different exposure conditions.