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Title: Characterization of Tight Gas Reservoir Pore Structure Using USANS/SANS and Gas Adsorption Analysis

Abstract

Small-angle and ultra-small-angle neutron scattering (SANS and USANS) measurements were performed on samples from the Triassic Montney tight gas reservoir in Western Canada in order to determine the applicability of these techniques for characterizing the full pore size spectrum and to gain insight into the nature of the pore structure and its control on permeability. The subject tight gas reservoir consists of a finely laminated siltstone sequence; extensive cementation and moderate clay content are the primary causes of low permeability. SANS/USANS experiments run at ambient pressure and temperature conditions on lithologically-diverse sub-samples of three core plugs demonstrated that a broad pore size distribution could be interpreted from the data. Two interpretation methods were used to evaluate total porosity, pore size distribution and surface area and the results were compared to independent estimates derived from helium porosimetry (connected porosity) and low-pressure N{sub 2} and CO{sub 2} adsorption (accessible surface area and pore size distribution). The pore structure of the three samples as interpreted from SANS/USANS is fairly uniform, with small differences in the small-pore range (< 2000 {angstrom}), possibly related to differences in degree of cementation, and mineralogy, in particular clay content. Total porosity interpreted from USANS/SANS is similar to (butmore » systematically higher than) helium porosities measured on the whole core plug. Both methods were used to estimate the percentage of open porosity expressed here as a ratio of connected porosity, as established from helium adsorption, to the total porosity, as estimated from SANS/USANS techniques. Open porosity appears to control permeability (determined using pressure and pulse-decay techniques), with the highest permeability sample also having the highest percentage of open porosity. Surface area, as calculated from low-pressure N{sub 2} and CO{sub 2} adsorption, is significantly less than surface area estimates from SANS/USANS, which is due in part to limited accessibility of the gases to all pores. The similarity between N{sub 2} and CO{sub 2}-accessible surface area suggests an absence of microporosity in these samples, which is in agreement with SANS analysis. A core gamma ray profile run on the same core from which the core plug samples were taken correlates to profile permeability measurements run on the slabbed core. This correlation is related to clay content, which possibly controls the percentage of open porosity. Continued study of these effects will prove useful in log-core calibration efforts for tight gas.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [3];  [1];  [1]
  1. ORNL
  2. Indiana Geological Survey
  3. University of British Columbia, Vancouver
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1034705
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Fuel
Additional Journal Information:
Journal Volume: 95; Journal Issue: 1; Journal ID: ISSN 0016-2361
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; ADSORPTION; CALIBRATION; CANADA; CLAYS; DISTRIBUTION; GASES; HELIUM; MINERALOGY; NATURAL GAS DEPOSITS; NEUTRON DIFFRACTION; PERMEABILITY; PORE STRUCTURE; POROSITY; SMALL ANGLE SCATTERING; SILTSTONES; SURFACE AREA

Citation Formats

Clarkson, Christopher R, He, Lilin, Agamalian, Michael, Melnichenko, Yuri B, Mastalerz, Maria, Bustin, Mark, Radlinski, Andrzej Pawell, and Blach, Tomasz P. Characterization of Tight Gas Reservoir Pore Structure Using USANS/SANS and Gas Adsorption Analysis. United States: N. p., 2012. Web. doi:10.1016/j.fuel.2011.12.010.
Clarkson, Christopher R, He, Lilin, Agamalian, Michael, Melnichenko, Yuri B, Mastalerz, Maria, Bustin, Mark, Radlinski, Andrzej Pawell, & Blach, Tomasz P. Characterization of Tight Gas Reservoir Pore Structure Using USANS/SANS and Gas Adsorption Analysis. United States. https://doi.org/10.1016/j.fuel.2011.12.010
Clarkson, Christopher R, He, Lilin, Agamalian, Michael, Melnichenko, Yuri B, Mastalerz, Maria, Bustin, Mark, Radlinski, Andrzej Pawell, and Blach, Tomasz P. 2012. "Characterization of Tight Gas Reservoir Pore Structure Using USANS/SANS and Gas Adsorption Analysis". United States. https://doi.org/10.1016/j.fuel.2011.12.010.
@article{osti_1034705,
title = {Characterization of Tight Gas Reservoir Pore Structure Using USANS/SANS and Gas Adsorption Analysis},
author = {Clarkson, Christopher R and He, Lilin and Agamalian, Michael and Melnichenko, Yuri B and Mastalerz, Maria and Bustin, Mark and Radlinski, Andrzej Pawell and Blach, Tomasz P},
abstractNote = {Small-angle and ultra-small-angle neutron scattering (SANS and USANS) measurements were performed on samples from the Triassic Montney tight gas reservoir in Western Canada in order to determine the applicability of these techniques for characterizing the full pore size spectrum and to gain insight into the nature of the pore structure and its control on permeability. The subject tight gas reservoir consists of a finely laminated siltstone sequence; extensive cementation and moderate clay content are the primary causes of low permeability. SANS/USANS experiments run at ambient pressure and temperature conditions on lithologically-diverse sub-samples of three core plugs demonstrated that a broad pore size distribution could be interpreted from the data. Two interpretation methods were used to evaluate total porosity, pore size distribution and surface area and the results were compared to independent estimates derived from helium porosimetry (connected porosity) and low-pressure N{sub 2} and CO{sub 2} adsorption (accessible surface area and pore size distribution). The pore structure of the three samples as interpreted from SANS/USANS is fairly uniform, with small differences in the small-pore range (< 2000 {angstrom}), possibly related to differences in degree of cementation, and mineralogy, in particular clay content. Total porosity interpreted from USANS/SANS is similar to (but systematically higher than) helium porosities measured on the whole core plug. Both methods were used to estimate the percentage of open porosity expressed here as a ratio of connected porosity, as established from helium adsorption, to the total porosity, as estimated from SANS/USANS techniques. Open porosity appears to control permeability (determined using pressure and pulse-decay techniques), with the highest permeability sample also having the highest percentage of open porosity. Surface area, as calculated from low-pressure N{sub 2} and CO{sub 2} adsorption, is significantly less than surface area estimates from SANS/USANS, which is due in part to limited accessibility of the gases to all pores. The similarity between N{sub 2} and CO{sub 2}-accessible surface area suggests an absence of microporosity in these samples, which is in agreement with SANS analysis. A core gamma ray profile run on the same core from which the core plug samples were taken correlates to profile permeability measurements run on the slabbed core. This correlation is related to clay content, which possibly controls the percentage of open porosity. Continued study of these effects will prove useful in log-core calibration efforts for tight gas.},
doi = {10.1016/j.fuel.2011.12.010},
url = {https://www.osti.gov/biblio/1034705}, journal = {Fuel},
issn = {0016-2361},
number = 1,
volume = 95,
place = {United States},
year = {2012},
month = {1}
}