Mechanical and Structural Behavior of Swelling Elastomers under Compressive Loading

Abstract

Swelling elastomers are a new breed of advanced polymers, and found increasing use in drilling of difficult oil and gas wells. It is important to know how an elastomer will behave under a given set of well conditions, especially after the initial quick-swell period. Good design depends on appropriate material selection. Results are presented in this chapter from experimental and numerical studies conducted to analyze how compressive and bulk behavior of actual oilfield elastomers changes due to swelling. Six key attributes of swelling elastomers needed for design improvement and performance analysis of elastomer seals are discussed: four mechanical properties (elastic modulus E, bulk modulus K, shear modulus G, and Poisson’s ratio ν), and two polymer structure characteristics (cross-link chain density NC, and average molecular weight MC). These parameters were experimentally determined before and after various stages of swelling for two different swelling elastomers being currently used by the regional petroleum industry, in low and high salinity brines. To strengthen the experimental results, and to be able to forecast for other elastomer materials and well conditions, tests were also simulated using the commercial FEM package ABAQUS, using the best available hyperelastic material models.