Imaging wellbore cement degradation by carbon dioxide under geologic sequestration conditions using X-ray computed microtomography.

X-ray microtomography (XMT), a nondestructive three-dimensional imaging technique, was applied to demonstrate its capability to visualize the mineralogical alteration and microstructure changes in hydrated Portland cement exposed to carbon dioxide under geologic sequestration conditions. Steel coupons and basalt fragments were added to the cement paste in order to simulate cement-steel and cement-rock interfaces. XMT image analysis showed the changes of material density and porosity in the degradation front (density: 1.98 g/cm(3), porosity: 40%) and the carbonated zone (density: 2.27 g/cm(3), porosity: 23%) after reaction with CO(2)-saturated water for 5 months compared to unaltered cement (density: 2.15 g/cm(3), porosity: 30%). Three-dimensional XMT imaging was capable of displaying spatially heterogeneous alteration in cement pores, calcium carbonate precipitation in cement cracks, and preferential cement alteration along the cement-steel and cement-rock interfaces. This result also indicates that the interface between cement and host rock or steel casing is likely more vulnerable to a CO(2) attack than the cement matrix in a wellbore environment. It is shown here that XMT imaging can potentially provide a new insight into the physical and chemical degradation of wellbore cement by CO(2) leakage.

[1]  Mark L. Rivers,et al.  Using X-ray computed tomography in hydrology: systems, resolutions, and limitations , 2002 .

[2]  F. Brunet,et al.  Effect of carbonation on the hydro-mechanical properties of Portland cements , 2009 .

[3]  Karen L. Scrivener,et al.  Backscattered electron imaging of cementitious microstructures: Understanding and quantification , 2004 .

[4]  Jeffrey J. Thomas,et al.  Effect of carbonation on the nitrogen BET surface area of hardened portland cement paste , 1996 .

[5]  Neil Hunter,et al.  Characterization of a novel calibration method for mineral density determination of dentine by X-ray micro-tomography. , 2009, The Analyst.

[6]  M. Rivers,et al.  Evaluation of synchrotron X-ray computerized microtomography for the visualization of transport processes in low-porosity materials. , 2005, Journal of contaminant hydrology.

[7]  J. Carey,et al.  Geochemical effects of CO2 sequestration on fractured wellbore cement at the cement/caprock interface , 2009 .

[8]  Eric N. Landis,et al.  X-ray microtomographic studies of pore structure and permeability in Portland cement concrete , 2005 .

[9]  Kimberly E. Kurtis,et al.  X-ray microtomography (microCT) of the progression of sulfate attack of cement paste , 2002 .

[10]  J. Carey,et al.  Experimental investigation of wellbore integrity and CO2–brine flow along the casing–cement microannulus , 2010 .

[11]  B. Kutchko,et al.  Degradation of well cement by CO2 under geologic sequestration conditions. , 2007, Environmental science & technology.

[12]  B. Kutchko,et al.  CO2 reaction with hydrated class H well cement under geologic sequestration conditions: effects of flyash admixtures. , 2009, Environmental science & technology.

[13]  Christopher J. Spiers,et al.  Fracture healing and transport properties of wellbore cement in the presence of supercritical CO2 , 2011 .

[14]  F. Brunet,et al.  Calcium carbonates distribution in experimentally carbonated Portland cement cores , 2009 .

[15]  F. Brunet,et al.  Heterogeneous Porosity Distribution in Portland Cement Exposed to CO2-rich Fluids , 2008 .

[16]  Virginie Busignies,et al.  Quantitative measurements of localized density variations in cylindrical tablets using X-ray microtomography. , 2006, European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V.

[17]  B. Kutchko,et al.  Rate of CO2 attack on hydrated Class H well cement under geologic sequestration conditions. , 2008, Environmental science & technology.

[18]  N. Burlion,et al.  The behavior of oil well cement at downhole CO2 storage conditions: Static and dynamic laboratory experiments , 2011 .

[19]  Jeffrey J. Thomas,et al.  Composition and density of nanoscale calcium-silicate-hydrate in cement. , 2007, Nature materials.

[20]  Keith W. Jones,et al.  Synchrotron computed microtomography of porous media: Topology and transports. , 1994, Physical review letters.

[21]  Dork L. Sahagian,et al.  Synchrotron X-ray computed microtomography: studies on vesiculated basaltic rocks , 2001 .

[22]  Ke Xu,et al.  Microstructure and transport properties of porous building materials , 1998 .

[23]  F. Peyrin,et al.  Microstructure and transport properties of porous building materials. II: Three-dimensional X-ray tomographic studies , 2000 .

[24]  Michael Angelo B. Promentilla,et al.  Application of synchrotron microtomography for pore structure characterization of deteriorated cementitious materials due to leaching , 2010 .

[25]  G. Nagy,et al.  Technique to measure 3D work-of-fracture of concrete in compression , 1999 .

[26]  Kenneth C. Hover,et al.  Mercury porosimetry of hardened cement pastes , 1999 .

[27]  Frédéric Skoczylas,et al.  About Microcracking Due to Leaching in Cementitious Composites: X-ray Microtomography Description and Numerical Approach , 2010 .

[28]  G. Scherer,et al.  Degradation of oilwell cement due to exposure to carbonated brine , 2010 .

[29]  J.G.M. van Mier,et al.  How to study drying shrinkage microcracking in cement-based materials using optical and scanning electron microscopy? , 2002 .

[30]  Michael A. Celia,et al.  Spatial characterization of the location of potentially leaky wells penetrating a deep saline aquifer in a mature sedimentary basin , 2004 .

[31]  P. Lichtner,et al.  Analysis and performance of oil well cement with 30 years of CO2 exposure from the SACROC Unit, West Texas, USA , 2007 .

[32]  E. Landis,et al.  X-ray microtomography , 2010 .