Injection of a CO2-Reactive Solution for Wellbore Annulus Leakage Remediation

Abstract

Driven by concerns for safe storage of CO2, substantial effort has been directed on wellbore integrity simulations over the last decade. Since large scale demonstrations of CO2 storage are planned for the near-future, numerical tools predicting wellbore integrity at field scale are essential to capture the processes of potential leakage and assist in designing leakage mitigation measures. Following this need, we developed a field-scale wellbore model incorporating (1) a de-bonded interface between cement and rock, (2) buoyancy/pressure driven (microannulus) flow of brine and CO2, (3) CO2 diffusion and reactivity with cement and (4) chemical cement-rock interaction. The model is aimed at predicting leakage through the microannulus and specifically at assessing methods for CO2 leakage remediation. The simulations show that for a low enough initial leakage rate, CO2 leakage is self-limiting due to natural sealing of the microannulus by mineral precipitation. With a high leakage rate, CO2 leakage results in progressive cement leaching. In case of sustained leakage, a CO2 reactive solution can be injected in the microannulus to induce calcite precipitation and block the leak path. The simulations showed full clogging of the leak path and increased sealing with time after remediation, indicating the robustness of the leakage remediation by mineral precipitation.

Advances and Prospects of Supercritical CO2 for Shale Gas Extraction and Geological Sequestration in Gas Shale Reservoirs

“…A longer residence time of calcite water led to larger amounts of in situ precipitated minerals, which also promoted self-healing in CO 2 storage wells. Wolterbeek and Wasch and Koenen investigated microannular damage and found that injecting water containing Ca 2+ ions into fractures within the damaged cement sheath could lead to calcite water reacting with CO 2 in the fractures, resulting in the formation of solidified calcium carbonate. This effectively sealed the fractures and demonstrated the self-healing capability of CO 2 storage wells.…”

Remediation of Annular Gas Migration along Cemented Wellbores Using Reactive Mineral Fluids: Experimental Assessment of Sodium Bicarbonate and Sodium Silicate-Based Solutions

“…Under flow conditions, it was found these reactions can lead to effective self-sealing of micro-annuli, provided that the precipitation of carbonates locally outstrips dissolution of cement phases. This prompted several workers to speculate whether CO 2 -rich fluids could be employed in wellbore seepage remediation [49,50]. Conversely, however, if dissolution dominates, then reactive transport could conceivably lead to extensive cement degradation and self-enhanced seepage, with sealing integrity worsening over time [65].…”

A multiphysical‐geochemical coupling model for caprock sealing efficiency in CO2 geosequestration

“…More and more studies have shown that CO 2 possibly migrates to shallow aquifers and pollutes freshwater resources (Carroll et al, 2014; Keating et al, 2013; Ruggieri & Gherardi, 2020; Smith et al, 2013; Takaya et al, 2017; Wang & Wang, 2018). This CO 2 leakage to freshwater layers may cause groundwater acidification (Apps et al, 2010), heavy metal mobilization (Frye et al, 2012), or mineral dissolution (Fazeli et al, 2019; Wang et al, 2023; Wang & Jaffe, 2004; Wasch & Koenen, 2019). Therefore, a comprehensive risk assessment of caprock integrity or caprock sealing efficiency is an essential task for CO 2 geosequestration safety.…”