Pore structure characterization of Chang-7 tight sandstone using MICP combined with N2GA techniques and its geological control factors

Understanding the pore networks of unconventional tight reservoirs such as tight sandstones and shales is crucial for extracting oil/gas from such reservoirs. Mercury injection capillary pressure (MICP) and N2 gas adsorption (N2GA) are performed to evaluate pore structure of Chang-7 tight sandstone. Thin section observation, scanning electron microscope, grain size analysis, mineral composition analysis, and porosity measurement are applied to investigate geological control factors of pore structure. Grain size is positively correlated with detrital mineral content and grain size standard deviation while negatively related to clay content. Detrital mineral content and grain size are positively correlated with porosity, pore throat radius and withdrawal efficiency and negatively related to capillary pressure and pore-to-throat size ratio; while interstitial material is negatively correlated with above mentioned factors. Well sorted sediments with high debris usually possess strong compaction resistance to preserve original pores. Although many inter-crystalline pores are produced in clay minerals, this type of pores is not the most important contributor to porosity. Besides this, pore shape determined by N2GA hysteresis loop is consistent with SEM observation on clay inter-crystalline pores while BJH pore volume is positively related with clay content, suggesting N2GA is suitable for describing clay inter-crystalline pores in tight sandstones.

[1]  R. Marc Bustin,et al.  Characterization of gas shale pore systems by porosimetry, pycnometry, surface area, and field emission scanning electron microscopy/transmission electron microscopy image analyses: Examples from the Barnett, Woodford, Haynesville, Marcellus, and Doig units , 2012 .

[2]  Celso Peres Fernandes,et al.  Characterization of pore systems in seal rocks using Nitrogen Gas Adsorption combined with Mercury Injection Capillary Pressure techniques , 2013 .

[3]  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.

[4]  Philip L. Walker,et al.  Nature of the porosity in American coals , 1972 .

[5]  Christopher R. Clarkson,et al.  Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion , 2013 .

[6]  R. Marc Bustin,et al.  The importance of shale composition and pore structure upon gas storage potential of shale gas reservoirs , 2009 .

[7]  K. Sing Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984) , 1985 .

[8]  Guiwen Wang,et al.  Impact of diagenesis on the reservoir quality of tight oil sandstones: The case of Upper Triassic Yanchang Formation Chang 7 oil layers in Ordos Basin, China , 2016 .

[9]  Maria Mastalerz,et al.  Characterization of tight gas reservoir pore structure using USANS/SANS and gas adsorption analysis , 2012 .

[10]  I. Akkutlu,et al.  Pore-Size Dependence of Fluid Phase Behavior and Properties in Organic-Rich Shale Reservoirs , 2013 .

[11]  K. Bjørlykke Relationships between depositional environments, burial history and rock properties. Some principal aspects of diagenetic process in sedimentary basins , 2014 .

[12]  Rui Kou,et al.  Coupling of Darcy's Equation with Molecular Transport and its Application to Upscaling Kerogen Permeability , 2016 .

[13]  K. Newsham,et al.  Sample Size Effects on the Application of Mercury Injection Capillary Pressure for Determining the Storage Capacity of Tight Gas and Oil Shales , 2011 .

[14]  Christopher R. Clarkson,et al.  Variation in micropore capacity and size distribution with composition in bituminous coal of the Western Canadian Sedimentary Basin: Implications for coalbed methane potential , 1996 .

[15]  G. Kocurek The Petrology of the Sedimentary Rocks , 1938, Nature.

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

[17]  J. M. Kate,et al.  A simple method to estimate complete pore size distribution of rocks , 2006 .

[18]  F. Tompkins Physical adsorption on non-uniform surfaces , 1950 .

[19]  Zhaoping Meng,et al.  A preliminary study on the pore characterization of Lower Silurian black shales in the Chuandong Thrust Fold Belt, southwestern China using low pressure N2 adsorption and FE-SEM methods , 2013 .

[20]  K. Gubbins,et al.  A Grand Canonical Monte Carlo Study of Adsorption and Capillary Phenomena in Nanopores of Various Morphologies and Topologies: Testing the BET and BJH Characterization Methods , 2004 .

[21]  Robert L. Folk,et al.  A REVIEW OF GRAIN‐SIZE PARAMETERS , 1966 .

[22]  Javier Pérez-Ramírez,et al.  Pore size determination in modified micro- and mesoporous materials. Pitfalls and limitations in gas adsorption data analysis , 2003 .

[23]  J. Wilcox,et al.  Molecular simulation of methane adsorption in micro- and mesoporous carbons with applications to coal and gas shale systems , 2013 .

[24]  N. Wardlaw,et al.  Oil Recovery Efficiency and the Rock-Pore Properties of Some Sandstone Reservoirs , 1979 .

[25]  Hillar M. Rootare,et al.  Surface areas from mercury porosimeter measurements , 1967 .

[26]  Christopher R. Clarkson,et al.  Innovative methods for flow-unit and pore-structure analyses in a tight siltstone and shale gas reservoir , 2012 .

[27]  R. Bustin,et al.  Geological controls on coalbed methane reservoir capacity and gas content , 1998 .

[28]  Ang Li,et al.  Investigation of pore structure and fractal characteristics of organic-rich shale reservoirs: A case study of Lower Cambrian Qiongzhusi formation in Malong block of eastern Yunnan Province, South China , 2016 .

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

[30]  Chengyun Wang,et al.  Lacustrine tight oil accumulation characteristics: Permian Lucaogou Formation in Jimusaer Sag, Junggar Basin , 2016 .

[31]  Filip Hjulstrom,et al.  Transportation of Detritus by Moving Water , 1955 .

[32]  Yu-Feng Deng,et al.  Late Triassic tuff intervals in the Ordos basin, Central China: Their depositional, petrographic, geochemical characteristics and regional implications , 2014 .

[33]  U. Kuila,et al.  Specific surface area and pore‐size distribution in clays and shales , 2013 .

[34]  Xiong Jian,et al.  Investigation of pore structure and fractal characteristics of organic-rich Yanchang formation shale in central China by nitrogen adsorption/desorption analysis , 2015 .

[35]  Maria Mastalerz,et al.  Variations in pore characteristics in high volatile bituminous coals: Implications for coal bed gas content , 2008 .

[36]  R. Folk,et al.  Brazos River bar [Texas]; a study in the significance of grain size parameters , 1957 .

[37]  Xin Li,et al.  Alkaline diagenesis and its effects on reservoir porosity: A case study of Upper Triassic Chang 7 Member tight sandstone in Ordos Basin, NW China , 2015 .

[38]  S. J. Gregg,et al.  Adsorption Surface Area and Porosity , 1967 .

[39]  C. P. Fernandes,et al.  Characterization of Brazilian tight gas sandstones relating permeability and Angstrom-to micron-scale pore structures , 2015 .

[40]  L. C. Drake,et al.  Pressure Porosimeter and Determination of Complete Macropore-Size Distributions. Pressure Porosimeter and Determination of Complete Macropore-Size Distributions , 1945 .

[41]  E. Barrett,et al.  (CONTRIBUTION FROM THE MULTIPLE FELLOWSHIP OF BAUGH AND SONS COMPANY, MELLOX INSTITUTE) The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms , 1951 .

[42]  Roman Loser,et al.  Analysis of cement-bonded materials by multi-cycle mercury intrusion and nitrogen sorption. , 2009, Journal of colloid and interface science.

[43]  V. Rudolph,et al.  Fractal analysis in pore structure of coal under conditions of CO2 sequestration process , 2015 .

[44]  Christopher R. Clarkson,et al.  Production Analysis of Western Canadian Unconventional Light Oil Plays , 2011 .

[45]  Amanda M. M. Bustin,et al.  Impact of Shale Properties on Pore Structure and Storage Characteristics , 2008 .

[46]  Jef Vandenberghe,et al.  Comparison of laser grain size analysis with pipette and sieve analysis: a solution for the underestimation of the clay fraction , 1997 .

[47]  Guochang Wang,et al.  Pore structure characteristics of coal-bearing shale using fluid invasion methods: A case study in the Huainan–Huaibei Coalfield in China , 2015 .

[48]  Christopher R. Clarkson,et al.  The effect of pore structure and gas pressure upon the transport properties of coal: a laboratory and modeling study. 1. Isotherms and pore volume distributions , 1999 .

[49]  P. Peng,et al.  Uranium enrichment in lacustrine oil source rocks of the Chang 7 member of the Yanchang Formation, Erdos Basin, China , 2010 .