Elastomer seals in cold expansion of petroleum tubulars: Comparison of material models

Because of its ability to significantly reduce well costs, together with improvement of well functionality and performance, expandable technology is becoming popular in the oil and gas industry. Based on the well-established manufacturing method of cold expansion, novel downhole applications of this technology include expandable drilling liners, expandables, and screens, expandable casing cladding systems, and expandable liner hangers. All expandable applications need an effective sealing mechanism. One of the newest developments in seal design is the use of swelling elastomers: rubber-like materials that swell upon contact with water or oil. The authors are involved in several projects targeted at improvement of seal design and manufacturing in petroleum applications. Work reported in this article focuses on experimental and numerical (FEM) investigation of the tensile behavior of two swelling elastomers. Treating swelling elastomers as a type of hyperelastic material, coefficients for the more popular hyperelastic material models (Ogden, Yeoh, Arruda-Boyce, and Neo-Hookean) are determined using curve fitting procedures available in ABAQUS. Models are compared with each other in predicting the tensile behavior for both unswelled and swelled conditions. Neo-Hookean model appears to give the overall best results for tensile behavior of the two elastomers under swelled and unswelled states.