Experimental Setup to Investigate the Permeability of Annular Cement to Fluid Flow

Abstract

Abstract Well integrity issues have been widely studied in the oil and gas sector; however, with storage wells (e.g. towards natural gas, CO2 and H2), new challenges may arise due to the reactivity of the stored fluid in contact with well barrier materials, including migration and leakage of fluids. It is therefore essential to study the reaction of fluids with cement in well conditions to be able to predict the evolution of the cement annulus when exposed to fluids. We have performed fluid flow experiments through realistic cracks in an annular cement sheath in a downscaled wellbore section. Two different experimental procedures to measure fluid flow have been investigated. The setup consists of a steel casing, cement sheath and surrounding rock. This setup provides a unique possibility to perform pressure cycling experiments to investigate cement sheath integrity and subsequent flow measurement across the 30—cm long cement sheath. We compare the evolution of the flow rate of both gas (N2) and brine (liquid). Fluid flow testing with N2 and brine provides a reference measurement of the micro annuli permeability for both liquid and gas phases. As nitrogen does not react with cement, it provides a reference flow measurement. This paper reports initial and new results, measuring fluid flow as a function of inner casing pressure of a downscaled wellbore section.