Sealing Performance of Geopolymer for Plugging and Abandonment; Apple-to-Apple Scenario

Abstract

Abstract Sealability of barrier material is required for successful plug and abandonment operations. The emergence of geopolymer as a green alternative to ordinary Portland cement presents an option for well abandonment in a more environmentally friendly manner. Sealability of geopolymer in terms of hydraulic and shear bond strength (key factors in evaluating the interfacial properties of the cement-casing interface) is compared to that of API Class G cement at 25°C and at a pressure of 34.5 bar (500 psi). The hydraulic sealability was measured with a custom-made setup, which allows the measurement to be taken continuously from the curing stage of the various cementitious materials with eliminating any pressure and temperature shocks. Thus, mimicking downhole conditions for the hydraulic sealability behavior of the cementitious materials used in our study. In addition, the push-out test was used to characterize the shear bond strength between the casing-cement interfaces. The volume shrinkage behavior was studied for both materials. The volume shrinkage of the Neat G cement was found to occur very quickly during and after the hydration reaction resulting in a total shrinkage of 2.4% whiles that of the geopolymer undergoes a shrinkage of 2.2%. The shear bond strength of the geopolymer lesser than that of the Neat G cement, it was able to match the Neat G cement in terms of the hydraulic bond strength. This is reveals that the rock-based geopolymer can be an alternative for zonal isolation as well as revealing that hydraulic bond strength and hydraulic sealability should be the main factors for barrier qualification.