title: Confinement Correction to Mercury Intrusion Capillary Pressure of Shale Nanopores.
abstract: We optimized potential parameters in a molecular dynamics model to reproduce the experimental contact angle of a macroscopic mercury droplet on graphite. With the tuned potential, we studied the effects of pore size, geometry, and temperature on the wetting of mercury droplets confined in organic-rich shale nanopores. The contact angle of mercury in a circular pore increases exponentially as pore size decreases. In conjunction with the curvature-dependent surface tension of liquid droplets predicted from a theoretical model, we proposed a technique to correct the common interpretation procedure of mercury intrusion capillary pressure (MICP) measurement for nanoporous material such as shale. Considering the variation of contact angle and surface tension with pore size improves the agreement between MICP and adsorption-derived pore size distribution, especially for pores having a radius smaller than 5 nm. The relative error produced in ignoring these effects could be as high as 44%--samples that contain smaller pores deviate more. We also explored the impacts of pore size and temperature on the surface tension and contact angle of water/vapor and oil/gas systems, by which the capillary pressure of water/oil/gas in shale can be obtained from MICP. This information is fundamental to understanding multiphase flow behavior in shale systems.
authors.affiliation: Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, United States.|School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, China.
authors.forename: Sen
authors.initials: S
authors.lastname: Wang
authors.affiliation: Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, TX, United States.
authors.forename: Farzam
authors.initials: F
authors.lastname: Javadpour
authors.affiliation: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, China.
authors.forename: Qihong
authors.initials: Q
authors.lastname: Feng
references.citation: Nature. 2013 Feb 21;494(7437):307-8
references.pmid: 23426309
references.citation: Nature. 1997 Dec 4;390(6659):465-71
references.pmid: 9393997
references.citation: Science. 2005 Dec 2;310(5753):1480-3
references.pmid: 16322454
references.citation: Langmuir. 2005 Jan 18;21(2):779-81
references.pmid: 15641854
references.citation: Phys Rev E Stat Nonlin Soft Matter Phys. 2001 Mar;63(3 Pt 1):031601
references.pmid: 11308656
references.citation: Science. 2010 Jun 25;328(5986):1624-6
references.pmid: 20576864
references.citation: J Am Chem Soc. 2005 Nov 9;127(44):15346-7
references.pmid: 16262379
references.citation: Langmuir. 2013 Feb 5;29(5):1457-65
references.pmid: 23320893
references.citation: Nat Mater. 2003 Jul;2(7):457-60
references.pmid: 12819775
references.citation: ACS Nano. 2010 Jul 27;4(7):3548-53
references.pmid: 20695511
references.citation: Nature. 2005 Nov 3;438(7064):44
references.pmid: 16267546
references.citation: J Chem Phys. 2006 Feb 7;124(5):054504
references.pmid: 16468891
references.citation: J Colloid Interface Sci. 2002 Jun 1;250(1):175-90
references.pmid: 16290649
references.citation: J Chem Phys. 2014 Jan 21;140(3):034110
references.pmid: 25669366