Chemical Change Induced by CO 2 Leakage through Wellbore Cement and Casing Interfaces
12 Pages Posted: 8 Apr 2021
Date Written: February 15, 2021
Abstract
Damaged wellbores pose some of the greatest risks for CO2 leakage from underground storage reservoirs. If CO2 is injected into the subsurface, leakage may occur through fractures and cracks formed at the cement-casing interface due to deficient well completion, poor mud displacement, or damage during operation or abandonment. A review of the literature has shown that a range of cement fractures can be sealed through calcium carbonate precipitation, given appropriate fluid residence time and initial fracture aperture. In the presence of steel casing, studies have observed that iron carbonate precipitation may also play a key role in fracture sealing. Here we discuss results of cement-steel, cement-cement, and steel-steel core-flood experiments simulating CO2-brine leakage in these systems. The aim of this study is to quantify the chemical changes in the cement and steel materials upon exposure to CO2-equilibrated brine. Using a combination of surface profilometry measurements, X-ray tomography (XRCT) and solution chemistry analyses, we quantified the chemical changes within both the cement and steel phases. These new experimental data are needed to extend chemical degradation models and predict the long-term behavior of the casing-cement interface in the wellbore environment.
Keywords: carbon storage; cement alteration; casing alteration; carbon steel casing; reactive transport; porous media; well integrity; corrosion
JEL Classification: Q54; Q51
Suggested Citation: Suggested Citation