Rock Surface Roughness Could Hold the Key to Enhancing Reservoir Descriptions

Friday, May 17, 2024

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Course Credit: 0.15 CEU, 1.5 PDH

Friday, May 17, 2024 | 09:00AM – 10:00AM CT

Surface roughness is an essential rock parameter affecting all petrophysical properties that are surface sensitive including pore size and wettability. However, the surface roughness of pores is often ignored, which leads to inaccurate surface-related petrophysics such as the prediction of permeability and the interpretation of capillary pressure curves. This presentation shows how proper quantification of surface roughness is crucial for obtaining representative roughness-independent pore sizes for a wide selection of cores.

Surface roughness can be measured by contact techniques (e.g. stylus profilometer, atomic force microscopy), and non-contact techniques (e.g. optical measurements). To balance the FOV (field of view) and measurement representativeness, and to minimize artifacts, laser scanner confocal microscopy (LSCM) is selected in this study. In this presentation, both the 1D absolute increment surface roughness, Sr, as well as 2D interfacial area ratio of surface roughness, Sdr, are reported on a wide selection of core samples using LSCM. Results indicate that Sdr has a greater dynamic range than Sr, i.e., Sdr provides a more representative characterization of surface roughness, while both are valid and can be used interchangeable.

The LSCM derived roughness is then integrated in a novel way with other petrophysical techniques including BET (Brunauer-Emmett-Teller) gas adsorption and NMR (nuclear magnetic resonance) relaxation. Typically, the NMR surface relaxivity (r2) is calibrated using the specific surface-area from BET gas adsorption, however, this drastically underestimates the pore size due to surface roughness effects. We use Sr (or Sdr) measured from LSCM to correct r2 for surface roughness effects, and thereby obtain the roughness-independent NMR pore-size distribution relevant for permeability, capillary pressure, and other surface-related petrophysical parameters. Good agreement is found with the roughness-independent micro-CT pore-size distribution, which validates our novel technique, and highlights the importance of surface roughness characterization in NMR petrophysics.

Finally, an example of integrating the LSCM, BET and NMR techniques is presented for assessing the effect of aging a wide selection of cores in CO2 under reservoir conditions for prolonged times.

All content contained within this webinar is copyrighted by Gabriela Singer and its use and/or reproduction outside the portal requires express permission from Gabriela Singer.

Webinar recordings will be available on-demand within 1 business day of the webinar completion.

For those who attended the live webinar, your certificate will be available in your “Learner Profile” within 1 business day of the webinar completion.

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Course Chapters

1Rock Surface Roughness Could Hold the Key to Enhancing Reservoir Descriptions
Media Type: Webinar
Surface roughness is an essential rock parameter affecting all petrophysical properties that are surface sensitive including pore size and wettability. However, the surface roughness of pores is often ignored, which leads to inaccurate surface-related petrophysics such as the prediction of permeability and the interpretation of capillary pressure curves. This presentation shows how proper quantification of surface roughness is crucial for obtaining representative roughness-independent pore sizes for a wide selection of cores. Surface roughness can be measured by contact techniques (e.g. stylus profilometer, atomic force microscopy), and non-contact techniques (e.g. optical measurements). To balance the FOV (field of view) and measurement representativeness, and to minimize artifacts, laser scanner confocal microscopy (LSCM) is selected in this study. In this presentation, both the 1D absolute increment surface roughness, Sr, as well as 2D interfacial area ratio of surface roughness, Sdr, are reported on a wide selection of core samples using LSCM. Results indicate that Sdr has a greater dynamic range than Sr, i.e., Sdr provides a more representative characterization of surface roughness, while both are valid and can be used interchangeable. The LSCM derived roughness is then integrated in a novel way with other petrophysical techniques including BET (Brunauer-Emmett-Teller) gas adsorption and NMR (nuclear magnetic resonance) relaxation. Typically, the NMR surface relaxivity (r2) is calibrated using the specific surface-area from BET gas adsorption, however, this drastically underestimates the pore size due to surface roughness effects. We use Sr (or Sdr) measured from LSCM to correct r2 for surface roughness effects, and thereby obtain the roughness-independent NMR pore-size distribution relevant for permeability, capillary pressure, and other surface-related petrophysical parameters. Good agreement is found with the roughness-independent micro-CT pore-size distribution, which validates our novel technique, and highlights the importance of surface roughness characterization in NMR petrophysics. Finally, an example of integrating the LSCM, BET and NMR techniques is presented for assessing the effect of aging a wide selection of cores in CO2 under reservoir conditions for prolonged times. All content contained within this webinar is copyrighted by Gabriela Singer and its use and/or reproduction outside the portal requires express permission from Gabriela Singer. Webinar recordings will be available on-demand within 1 business day of the webinar completion. For those who attended the live webinar, your certificate will be available in your “Learner Profile” within 1 business day of the webinar completion.

Credits

Earn credits by completing this course0.15 CEU credit1.5 PDH credits

Speakers

Gabriela SingerSpeakerGabriela Singer (Leu) is a principal scientist contractor at Halliburton in the Sensor Physics department. She is a Nuclear Magnetic Resonance (NMR) scientist with technical papers and patents related to cores analysis and tool physics. Her recent work consists of characterizing the surface roughness of rocks and its integration into petrophysical applications for enhancing formation evaluation. Previously, she worked at Schlumberger for 12 years as a tool physicist at the Houston Formation Evaluation center in Houston TX, and as a senior research scientist in the Geology and Rock Physics department at Schlumberger-Doll Research in Cambridge, MA. She holds a BS in Physics from “Al. I. Cuza” University of Iasi, Romania, and a PhD in Nuclear Science and Engineering from the Massachusetts Institute of Technology.

Mark ProettModeratorMark Proett is a senior petroleum engineering consultant working in O&G upstream technology for over 40 years. He worked for Aramco Services Company (5 years), Halliburton (35 years) and Schlumberger (2 years). He is best known for his publications advocating the viability of formation testing-while-drilling (FTWD), which was introduced in 2002, in addition to focused sampling probes and automated QC testing methods. Proett has been awarded 82 US patents and authored more than 60 technical papers, most of which deal with sampling and testing analysis methods. Proett has been an SPWLA Distinguished Speaker and SPE Distinguished Lecturer. In 2008 he received the SPWLA Distinguished Technical Achievement Award, in 2013 he was given the SPE Gulf Coast Regional Formation Evaluation Award and in 2017 the SPWLA International Formation Evaluation Award. He has a bachelor-of-science degree in mechanical engineering from the University of Maryland and a master-of-science degree from Johns Hopkins University.