Image-based evaluation of the effect of CO2-rich brine on the pre-existing fracture system within wellbore cement under dynamic flow-through conditions

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Conference Proceeding

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The effect of greenhouse gas CO on global warming has motivated numerous studies and projects around the world, which investigate new technology named Carbon Capture and Storage (CCS). Effective implementation of CCS technology will require containment of injected CO into subsurface geological formations over hundreds of years. The performance of structural seals overlying reservoirs targeted for CO storage will rely upon the integrity of well-bore cements in active and abandoned wells subjected to fluids rich in CO . Micro fractures within the well-bore cement and micro-annulus at the casing-cement and formation-cement may lead to seepage of CO to the surface and/or fresh water aquifers. Thus, understanding CO -induced changes to the imperfections in the cement matrix is vital for safe and effective implementation of CCS and the impact such changes can have on the overall hydraulic conductivity of a wellbore system. This paper presents an experimental study that depicts changes of cement's internal structure due to the interaction with acidic brine through a system of purposefully induced fractures within the cement matrix. The reported study is unique in that it employs advanced imaging analyses to quantify CO -induced alteration of well-bore cements. Helical computerized axial tomography and high resolution micro-computed tomography was used to visualize several sub-volumes of flow-through cores. Furthermore, a complementary high-resolution surface profilometry allowed quantification of changes of the roughness of fracture walls and their impact on the fracture aperture as a result of cement-acidic brine interaction over 100 days. Copyright 2012 ARMA, American Rock Mechanics Association. 2 2 2 2 2 2 2

Publication Source (Journal or Book title)

46th US Rock Mechanics / Geomechanics Symposium 2012

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