Near well-bore sealing in the Bečej CO2 reservoir: Field tests of a silicate based sealant

• Published in: International journal of greenhouse gas control Vol. 83; pp. 156 - 165
• Main Authors: Wiese, Bernd U., Fleury, Marc, Basic, Ivan, Abdollahi, Jafar, Patrnogic, Aleksandar, Hofstee, Cor, Carlsen, Inge M., Wollenweber, Jens, Schmidt-Hattenberger, Cornelia, Drysdale, Robert, Karas, Dusan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2019; Elsevier
• Subjects: CO2 leakage; Earth Sciences; Reactive solution; Remediation; Reservoir management; Sciences of the Universe; Sealant; Silica; Water-Cut; Water-Cut; Reservoir management; Sealant; Reactive solution; CO2 leakage; Remediation; Silica
• ISSN: 1750-5836; 1878-0148
• DOI: 10.1016/j.ijggc.2019.01.027

•Develop a gel to block gas movement in CO2 reservoirs.•The gel is selectively reactive to CO2.•Design was focussed on field applicability. The formulation is flexible and can be modified for different conditions.•The large scale of a sealing experiment is unique in the history of CO2 storage research.•The European Storage Directive imposes a corrective measures plan as part of the license for demonstration-scale projects. A silica gel was applied in a porous gas reservoir, with the purpose of testing mitigation and remediation of CO2 leakage from geological storage reservoirs. The gel has a high strength and a very low water-like viscosity, that extends its applicability to small pore diameters and low permeability media. The gel was prepared and applied on-site with oilfield equipment. Mixing was upscaled from laboratory- to field-scale, including one unsuccessful attempt. Environmental concerns and additional health and safety requirements were modest as the formulation was composed only of the non-toxic commercial silica-based product Betol K28 T, acetic acid and fresh water. A well was selected and prepared in the Bečej natural CO2 field in Serbia, the well and reservoir were prepared and the gel was placed into a 600 m deep CO2- and CH4-bearing sandstone layer. The reservoir was selectively sealed to the gas cap through a fast, CO2-selective gelation, while the hydraulic pathways of the liquid-filled part of the reservoir remained open. In the regions where no CO2 was present the gelation reaction was slower and the kinetic was temperature-accelerated. A numerical model was used to simulate the impact of the pre-injection operational procedures and to quantify the impact on the temperature-dependent gelation time. The workflow aligns the needs of a research project with the interests and practical priorities of an operating company.