Materials for Well Integrity – Rheological Behavior Study

Abstract

Ordinary Portland cement has been the prime material used for well cementing and permanent well- abandonment. Occasionally, the properties of the Portland cement can be inadequate to fulfil the necessary requirements. Hence, alternative barrier materials have been suggested for use in primary cementing and permanent well-abandonment. Among these, geopolymers, expansive cement, pozzolan based material, and thermosetting resins can be good alternatives. This article presents the fluid properties and rheological behavior of the above-mentioned alternative materials. API neat class G cement is used as a reference material to compare the obtained results. Through this study, the bottom-hole circulating temperature (BHCT) and bottom-hole static temperature (BHST) are selected to be 65 and 90°C, respectively. The pressure is 2500 psi. These conditions are representative for most wells on the Norwegian continental shelf. The initial results include viscosity profile at BHCT, the effect of pressure on thickening time, and intensity of static fluid loss. Our results show that the barrier materials have their pros and cons. One material might be good for an application such as a squeeze cementing job while the other one may not fit this application. The viscosity measurements showed all the candidate barrier materials to be shear-thinning to some degree. Except for the pozzolan based sealant, all other selected materials presented right angle set and pressure- dependent consistency.