Mohammadreza Shafiei, Steve Bryant, Matthew Balhoff, Chun Huh, Roger T. Bonnecaze
Hydrogel Formulation for Sealing Cracked Wellbores for CO2 Storage
Appl. Rheol. 27:6 (2017) 64433 (8 pages)

Abstract: A challenge for underground CO₂ storage is the leakage of the buoyant supercritical gas through microcracks in wellbores that cannot be sealed with current oilfield cements that are too viscous and cannot penetrate the cracks. Polymer gels consisting of pH-sensitive hydrogel particles suspended in an aqueous solution offer a potential alternative. The rheology of aqueous solutions of Carbopol 934 as a model pH-sensitive gel is measured to find the compositions and pHs for both ease of injection and to seal cracks against the flow of bulk CO₂ and CO₂ dissolved in brine. The polymer gels have low viscosity at low pH and can easily flow into the microcracks. In the elevated pH of the microcracks, the particles swell creating a significant yield stress sufficient to seal leakage pathways. The yield stress reaches a maximum at pH 5 and it increases with increasing concentration. The flow curves of stress versus shear rate for all pHs and concentrations are well-described by the Herschel-Bulkley model with an exponent of about 0.34 except for highly acidic conditions when the gelant solutions show a much lower yield stresses and higher exponents. The flow curves can be collapsed onto a single universal flow curve rescaled with the yield stress, the low frequency shear modulus and the suspending fluid viscosity. The presence of salts, especially high valence salts, reduce the yield stress of the gels considerably. It is shown that the addition of chelating agents mitigates this effect and can restore more than 30% of the yield stress of the gelant. © 2017 Applied Rheology.

DOI 10.3933/ApplRheol-27-64433

-- full text PDF available for subscribers --

-- open access PDF extract available for non-subscribers --

---

You have no password-free access to Applied Rheology Online. If you are a subscriber, enter login details below. For password-free access, we need your IP address. Sample manuscripts for free download can be found here ►

---

download to disk (some browsers prefer this option)
login name
password

Purchase this article for 20 € ? ►

Forgotten your login details? Send an email with subject "AR login" to login@appliedrheology.org

---

Appl Rheol 27 (2017) issues:

           

---

© Applied Rheology 2018