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Experimental Rock Physics and Applied Geophysical Models for Long-Term Monitoring of Carbon Dioxide Injected Reservoirs

Mur, Alan (2014) Experimental Rock Physics and Applied Geophysical Models for Long-Term Monitoring of Carbon Dioxide Injected Reservoirs. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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New methods of frequency and stress dependent petrophysical modeling are developed to link and predict laboratory, well log, and seismic scale pore fluid and pressure effects. These effects include pressure induced pore expansion, dissolution and material loss, and fluid effects on bulk properties. Petrophysical models that incorporate wave propagation at ultrasonic, well log, and seismic frequencies are produced with effective pressure and fluid dependent elements in reservoir limestone and sandstone for the purpose of reservoir monitoring.
The petrophysical model introduces stress sensitivity elements into bulk and shear moduli to account for non-linear elastic behavior at the low effective pressure regimes. Stress effects are modeled by defining stiff and compliant pore classes with assigned stress sensitivities based on geometric properties. The c33 elastic constant is then modified to include frequency dependent attenuation in the P wave velocity model. The characteristic frequencies are defined by not only the passing wave frequency but also key properties including permeability, fluid viscosity, and bulk modulus. The model input parameters are derived from core measurements and multi-scale observations including core velocity measurements, scanning electron microscopy, and computed micro tomography.
Limestone dissolution is observed in laboratory experiments performed with reactor vessels at in situ conditions using CO2-H2O mixes. The petrophysical models are updated to reflect the observed dissolution results. Further, the before and after µCT analysis of the samples reveal internal porosity gains, accompanied by decreases in pore surface area to volume ratios, which are seen to be limiters in chemical reaction rates.
Finally, CO2 quantification techniques in reservoir pore space are explored. Modeled and observed properties are implemented to interpret repeat reflection seismic surveys in which changes in pore pressure and pore-filling fluid density occur. The Sandstone and limestone reservoir fluid substitution models are compared with seismic anomalies to delineate pressure effects from fluid property effects. Impedance models at the sandstone reservoir reveal a 25% maximum acoustic impedance decrease with a fluid substitution filling the reservoir with 75% CO2. This significant impedance difference leads to increased reflectivity, which is confirmed with actual 4-D reflection seismic surveying.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Mur, Alanajm43@pitt.eduAJM43
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairHarbert, Williamharbert@pitt.eduHARBERT
Committee MemberAbbott, MarkMAbbott1@pitt.eduMABBOTT1
Committee MemberAnderson, Thomas H.taco@pitt.eduTACO
Committee MemberBain, Danieldbain@pitt.eduDBAIN
Committee MemberSoong, YeeYee.Soong@NETL.DOE.GOV
Date: 29 May 2014
Date Type: Publication
Defense Date: 27 November 2013
Approval Date: 29 May 2014
Submission Date: 5 December 2013
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 252
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Geology and Planetary Science
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Rock Physics, Velocity Modeling, Enhanced Oil Recovery, EOR, Image Processing, Geochemistry, CO2 Sequestration
Date Deposited: 29 May 2014 21:45
Last Modified: 29 May 2019 05:15


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