Electrical and fluid flow properties of carbonate microporosity types from multiscale digital image analysis and mercury injection

Electrical and fluid flow properties of porous media are directly related to the morphology of pores and the connectivity of the pore network. Both are closely linked to the amount and type of intrinsic microporosity in carbonate rocks, which is not resolved by conventional techniques. Broad-ion-beam (BIB) milling produces high-quality true-two-dimensional cross sections for scanning electron microscopy (SEM) and enables accurate quantification of carbonate microporosity for the first time. The combination of BIB-SEM mosaics with optical micrographs yields a multiscale digital image analysis (MsDIA) spanning six orders of magnitude. In this paper, the pore structures of 12 different carbonate rock samples from various rock types are quantified using MsDIA. Mercury injection capillary pressure measurements are used to assess pore-throat properties. The quantified pore-structure parameters are correlated with plug measurements of electrical resistivity and permeability. Results indicate that petrophysical properties are closely linked to the type of microporosity, which is distinctive for a certain rock type. Rock types with crystalline microporosity, such as mudstone and dolomite, generally show good connectivity, in which the size of the pore-network determines if the rock favors either hydraulic or electric flow. Rock types with intercement or micromoldic microporosity, such as bindstone and travertine, show variations in connectivity due to layering and moldic micropores of biological origin. Furthermore, pore-size distributions (PSD) follow a power law in all samples, despite their depositional and diagenetic differences. The slope of the PSD correlates with the electric properties, in which samples with a steeper slope show lower cementation factors. The linearity of the power law distribution enables predictions of pore populations outside the investigated length scales.

[1]  J. Urai,et al.  The connectivity of pore space in mudstones: insights from high-pressure Wood's metal injection, BIB-SEM imaging, and mercury intrusion porosimetry , 2015 .

[2]  Anders Malthe-Sørenssen,et al.  Shale gas: Opportunities and challenges , 2013 .

[3]  J. Urai,et al.  Variations in the morphology of porosity in the Boom Clay Formation: insights from 2D high resolution BIB-SEM imaging and Mercury injection Porosimetry , 2013, Netherlands Journal of Geosciences - Geologie en Mijnbouw.

[4]  H. Chafetz Porosity in bacterially induced carbonates: Focus on micropores , 2013 .

[5]  M. Pope,et al.  Three-dimensional pore connectivity evaluation in a Holocene and Jurassic microbialite buildup , 2013 .

[6]  Jeff Gelb,et al.  The Ascent of 3D X-ray Microscopy in the Laboratory , 2013, Microscopy Today.

[7]  János Urai,et al.  BIB-SEM study of the pore space morphology in early mature Posidonia Shale from the Hils area, Germany , 2012 .

[8]  I. Hulea,et al.  Carbonate rock characterization and modeling: Capillary pressure and permeability in multimodal rocks—A look beyond sample specific heterogeneity , 2012 .

[9]  M. Curtis,et al.  Microstructural investigation of gas shales in two and three dimensions using nanometer-scale resolution imaging , 2012 .

[10]  János Urai,et al.  High-resolution 3D fabric and porosity model in a tight gas sandstone reservoir:A new approach to investigate microstructures from mm- to nm-scale combining argon beam cross-sectioning and SEM imaging , 2011 .

[11]  Ralf J. Weger,et al.  Effect of pore structure on electrical resistivity in carbonates , 2011 .

[12]  G. Dresen,et al.  Nanoscale porosity in SAFOD core samples (San Andreas Fault) , 2011 .

[13]  Mark A. Knackstedt,et al.  Pore scale characterization of carbonates at multiple scales: integration of micro-CT, BSEM and FIBSEM , 2010 .

[14]  Ralf J. Weger,et al.  Quantification of pore structure and its effect on sonic velocity and permeability in carbonates , 2009 .

[15]  János Urai,et al.  Morphology of the pore space in claystones - evidence from BIB/FIB ion beam sectioning and cryo-SEM observations , 2009 .

[16]  J. Somerville,et al.  Pore geometrical model for the resistivity of brine saturated rocks , 2009 .

[17]  Philip H. Nelson,et al.  Pore-throat sizes in sandstones, tight sandstones, and shales , 2009 .

[18]  E. Wachsman,et al.  Evaluation of the relationship between cathode microstructure and electrochemical behavior for SOFCs , 2009 .

[19]  Guido Blöcher,et al.  Settle3D - A numerical generator for artificial porous media , 2008, Comput. Geosci..

[20]  E. Kazemzadeh,et al.  A new approach for the determination of cementation exponent in different petrofacies with velocity deviation logs and petrographical studies in the carbonate Asmari formation , 2007 .

[21]  Wu Jian-kang,et al.  Resistance effect of electric double layer on liquid flow in microchannel , 2006 .

[22]  Arve Lonoy,et al.  Making sense of carbonate pore systems , 2006 .

[23]  Wang Kewen,et al.  Percolation network modeling of electrical properties of reservoir rock , 2005 .

[24]  S. Andréfouët,et al.  Remote Sensing of Geomorphology and Facies Patterns on a Modern Carbonate Ramp (Arabian Gulf, Dubai, U.A.E.) , 2005 .

[25]  John Kelly,et al.  Digital Core Laboratory: Petrophysical Analysis from 3D Imaging of Reservoir Core Fragments , 2005 .

[26]  M Ahr Wayne,et al.  Confronting the carbonate conundrum , 2005 .

[27]  A. Radlinski,et al.  Angstrom-to-millimeter characterization of sedimentary rock microstructure. , 2004, Journal of colloid and interface science.

[28]  G. Eberli,et al.  Discrimination of effective from ineffective porosity in heterogeneous Cretaceous carbonates, Al Ghubar field, Oman , 2003 .

[29]  G. Eberli,et al.  Factors controlling elastic properties in carbonate sediments and rocks , 2003 .

[30]  A. Cerepi,et al.  Pore microgeometry analysis in low-resistivity sandstone reservoirs , 2002 .

[31]  G. Eberli,et al.  Questioning carbonate diagenetic paradigms: evidence from the Neogene of the Bahamas , 2002 .

[32]  S. Luthi,et al.  Quantitative Characterization of Carbonate Pore Systems by Digital Image Analysis , 1998 .

[33]  R. Knight,et al.  Effects of pore structure and wettability on the electrical resistivity of partially saturated rocks—A network study , 1997 .

[34]  P. Sen,et al.  Formation factor of carbonate rocks with microporosity: model calculations , 1997 .

[35]  F. Jerry Lucia,et al.  Rock-Fabric/Petrophysical Classification of Carbonate Pore Space for Reservoir Characterization , 1995 .

[36]  Muhammad Sahimi,et al.  Flow and Transport in Porous Media and Fractured Rock: From Classical Methods to Modern Approaches , 1995 .

[37]  W. David Kennedy,et al.  Electrical efficiency -- A pore geometric theory for interpreting the electrical properties of reservoir rocks , 1994 .

[38]  P. Jackson,et al.  Resistivity/Porosity/Velocity Relationships from Downhole Logs: An Aid for Evaluating Pore Morphology , 1993 .

[39]  D. Turcotte Fractals and Chaos in Geology and Geophysics , 1992 .

[40]  R. Ehrlich,et al.  Petrography and reservoir physics; II, Relating thin section porosity to capillary pressure, the association between pore types and throat size , 1991 .

[41]  Robert Ehrlich,et al.  Petrography and reservoir physics; III, Physical models for permeability and formation factor , 1991 .

[42]  C. Krohn Sandstone fractal and Euclidean pore volume distributions , 1988 .

[43]  A. Katz,et al.  Prediction of rock electrical conductivity from mercury injection measurements , 1987 .

[44]  B. F. Swanson Microporosity In Reservoir Rocks - Its Measurement And Influence On Electrical Resistivity , 1985 .

[45]  Thompson,et al.  Fractal sandstone pores: Implications for conductivity and pore formation. , 1985, Physical review letters.

[46]  N. Wardlaw,et al.  Estimation of Recovery Efficiency by Visual Observation of Pore Systems in Reservoir Rocks , 1979 .

[47]  P. Choquette,et al.  Geologic Nomenclature and Classification of Porosity in Sedimentary Carbonates , 1970 .

[48]  J. J. Arps The Effect of Temperature on the Density and Electrical Resistivity of Sodium Chloride Solutions , 1953 .

[49]  G. E. Archie,et al.  Classification of Carbonate Reservoir Rocks and Petrophysical Considerations , 1952 .

[50]  E. W. Washburn Note on a Method of Determining the Distribution of Pore Sizes in a Porous Material. , 1921, Proceedings of the National Academy of Sciences of the United States of America.

[51]  J. Urai,et al.  A comparative study of representative 2D microstructures in Shaly and Sandy facies of Opalinus Clay (Mont Terri, Switzerland) inferred form BIB-SEM and MIP methods , 2014 .

[52]  Philippe Gouze,et al.  Electrical and flow properties of highly heterogeneous carbonate rocks , 2014 .

[53]  R. Loucks,et al.  Origin and Description of the Micropore Network within the Lower Cretaceous Stuart City Trend Tight-Gas Limestone Reservoir in Pawnee Field in South Texas , 2013 .

[54]  J. Urai,et al.  Pore morphology and distribution in the Shaly facies of Opalinus Clay (Mont Terri, Switzerland): Insights from representative 2D BIB–SEM investigations on mm to nm scale , 2013 .

[55]  R. Ambrose Micro-structure of gas shales and its effects on gas storage and production performance , 2011 .

[56]  M. Curtis,et al.  Structural Characterization of Gas Shales on the Micro- and Nano-Scales , 2010 .

[57]  Ralf J. Weger,et al.  Quantitative pore/rock type parameters in carbonates and their relationship to velocity deviations , 2006 .

[58]  G. A. Anderson,et al.  Saturation exponent n in well log interpretation: Another look at the permissible range , 2001 .

[59]  E. A. Beaumont,et al.  Exploring for Oil and Gas Traps : Treatise of Petroleum Geology : handbook of Petroleum Geology , 1999 .

[60]  J. R. Dixon,et al.  The Effect of Bimodal- Pore Size Distribution on Electrical Properties of Some Middle Eastern Limestones , 1990 .

[61]  R. J. Dunham Classification of Carbonate Rocks According to Depositional Textures , 1962 .

[62]  R. Folk Practical petrographic classification of limestones , 1959 .