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Preliminary Results of Pembina Cardium Core Analysis C.R. Clarkson and N. Solano (PhD Candidate)

© TOC, 2011. T. C. O. Preliminary Results of Pembina Cardium Core Analysis C.R. Clarkson and N. Solano (PhD Candidate). Outline. Objectives Well Locations Sampling and Measurements CT Scans N 2 Adsorption Analysis Comparison to Bakken and 2WS SANS/USANS Future Work. T. C. O. 1.

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Preliminary Results of Pembina Cardium Core Analysis C.R. Clarkson and N. Solano (PhD Candidate)

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  1. © TOC, 2011 T C O Preliminary Results of Pembina Cardium Core AnalysisC.R. Clarkson and N. Solano (PhD Candidate)

  2. Outline • Objectives • Well Locations • Sampling and Measurements • CT Scans • N2 Adsorption Analysis • Comparison to Bakken and 2WS • SANS/USANS • Future Work T C O 1

  3. Objectives • Select low-permeability oil reservoir samples from the Cardium Formation to perform preliminary laboratory experiments • Use X-Ray CT Scans to evaluate changes in rock density and porosity and use to evaluate locations for permeability measurements (+ density of measurements) • Use low-pressure adsorption and small-angle neutron scattering (SANS and USANS) to establish pore structure characteristics by facies • To date, only “muddier” intervals have been studied • Establish controls on pore structure variation • Establish relationship between pore structure and permeability 2

  4. Sampling/Measurements • CORES SAMPLED / ANALYZED: • 08-17-049-06W5, CORE #1, BOXES 3 – 13 • 08-04-049-06W5, CORE #4, BOXES 5 – 11 • 04-24-049-07W5, CORE #1, BOX 11; CORE #2, BOXES 1 – 5; CORE #3, BOXES 1 – 4 (FUTURE) • MEASUREMENTS (to date): • Coreplugs taken from 8-17 and sub-sampled for SANS/USANS (discs prepared) at NIST (1/2011) and ORNL (3/2011) • N2 adsorption analysis performed on 8-17 coreplugs for surface area/PSD (8/2011) • 8-17 and 8-4 full-diameter cores were “scout” (CT) scanned to identify locations for axial scans (7/2011) • Axial (CT) scans performed on 8-17 and 8-4 (8/2011) • Pulse-decay permeability measurements performed on 8-17 coreplugs 3

  5. LOCATIONS WITH CORES TO SAMPLE 4-24-49-7W5 08-17-49-6W5 8-4-49-6W5 4 Structure contour map: top of the Cardium SS

  6. 08-17-049-06W5 MD (m) Res CZ Cardium A a b 5

  7. AVAILABLE RCA (Whole core diam.) • Kmax, PHI, GRAIN DENSITY • SANS/USANS (Horizontal disks 10 mm diameter x 1 mm thick) • 3 disks from: 1374.3 m • 5 disks from: 1377.0 m • INTERVALS TO SAMPLE/ANALYZE • CTS: 1364.3 – 1377.8 m • SLABBING: 1364.3 – 1377.8 m • SAND BLASTING: 1364.3 – 1377.8 m • PROBE K: 1364.3 – 1377.8 m • XRF: 1364.3 – 1377.8 m CTS 6

  8. CT Scans 08-17-049-06W5 CT Scans: Scout Scans 1364.3 m Axial scan location 7

  9. Mean porosity= 9.1% Mean porosity= 7.2% Mean porosity= 8.6% Mean porosity= 7.8% Mean porosity= 7.0% Mean porosity= 6.5% 8 Mean porosity= 4.2% Mean porosity= 7.6% Mean porosity= 7.7%

  10. CT Scans 08-17-049-06W5 CT Scans: Scout Scans Axial scan location 1368.96 m 9

  11. Mean porosity= 14.0% Mean porosity= 12.4% Mean porosity= 10.0% Mean porosity= 13.9% Mean porosity= 10.0% Mean porosity= 13.6% 10 Mean porosity= 18.6% Mean porosity= 15.2% Mean porosity= 21.7%

  12. CT Scans 08-17-049-06W5 CT Scans: Scout Scans 1374.59 m Coreplugs Axial scan location 11

  13. Mean porosity= 8.6% Mean porosity= 8.0% Mean porosity= 8.8% Mean porosity= 9.5% Mean porosity= 9.0% Mean porosity= 9.9% 12 Mean porosity= 10.4% Mean porosity= 9.9% Mean porosity= 9.5%

  14. N2 Adsorption/Desorption Isotherms • Shape: qualitative assessment of pore structure • Adsorption/desorption hysteresis: • Type IV isotherms, mesoporous solids (2 nm < d < 50 nm) • Shape of hysteresis loop can be indicative of pore geometry • Interpret isotherm data in terms of surface area (ex. BET Theory) and pore size distributions (ex. BJH Theory) 15

  15. N2 Adsorption/Desorption Isotherms • Similar amounts of adsorption for all samples except D2 • Substantial mesopore volume • Hysteresis loops may be indicative of slit-shaped pores 16

  16. N2 Adsorption/Desorption • More adsorption in Bakken, less in 2WS • Differences in Hysteresis Loop Shape – • pore structure differences? 17

  17. N2 Adsorption/Desorption BJH Analysis (PSD) • Capillary condensation of vapours in mesoporous materials • Uses Kelvin equation to relate vapour pressure to pore size • Can use desorption (convention) or adsorption branch • (Figure) • Step AB: removal of capillary condensate • Step BC: removal of condensate from cores, multi-layer thinning of emptied (larger) pores Desorption analysis using BJH Theory From SPE 147397 18

  18. N2 Adsorption/Desorption BJH Analysis (PSD) • Primarily unimodal pore size (peak ~ 200 – 350 A, desorption) • Artifact at ~ 35 A on desorption curves • Small pore size translates into low permeability (later) 19

  19. N2 Adsorption/Desorption • Cardium-Bakken, similar pore sizes, but • difference in volume • 2WS – less mesoporosity 20

  20. N2 Adsorption/Desorption • Cardium-Bakken, similar pore sizes, but • difference in volume • 2WS – less mesoporosity 21

  21. N2 Adsorption/Desorption BJH Analysis (PSD) • Comparison to Montney tight gas reservoir • Permeability implications From Clarkson et al. AAPG Bulletin, in press 23

  22. N2 Adsorption/Desorption Relationship to Permeability • Can we relate pore structural parameters to permeability (dominant pore size, BET surface area?) • Currently gathering permeability/porosity data for Cardium so plot like the one on the right (Montney TG) can be developed From Clarkson et al. AAPG Bulletin, in press 26

  23. SANS/USANS • In a SANS experiment, a neutron beam is directed at a sample, and the neutrons are elastically scattered due to their interaction with nuclei of atoms in the sample • The scattering vector is related to a characteristic length scale (pore size) in the sample • SANS experiments, combined with USANS, also enable a wide distribution of pore sizes (~ 0.3 nm to ~ 10 μm) to be investigated From Melnichenko et al. (2009) 27

  24. SANS/USANS Analysis 28

  25. SANS/USANS • Similar scattering patterns for all except: • B1 and B2 exhibit a “hump” at large Q, maybe related to composition • Higher scattering intensity generally translates into higher porosity • Slope of linear portion of curves (power-law scattering) is close to -3 • For surface fractal geometry (equivalent pore space is uncorrelated spherical pores), slope is -3 to -4 SANS USANS 29

  26. SANS/USANS SANS/USANS • Comparison to Montney tight gas reservoir • Montney has greater slopes (-3.1 to -3.3) 30

  27. SANS/USANS SANS/USANS Fit of 1102A1 to PDSP model using PRINSAS 31

  28. SANS/USANS SANS/USANS 33

  29. Future Work • Gather profile permeability, XRF and additional pulse-decay permeability data • Relate pore structural information to permeability • Examine compositional and structural controls on porosity and permeability 34

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