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

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

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

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

W W W5 LOCATIONS WITH CORES TO SAMPLE Structure contour map: top of the Cardium SS 4

MD (m) CZ Cardium A a b W5 Res 5

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

CT Scans CT Scans: Scout Scans W5 Axial scan location m 7

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

CT Scans CT Scans: Scout Scans W5 Axial scan location m 9

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

CT Scans CT Scans: Scout Scans W5 Axial scan location m Coreplugs 11

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

CT Scans CT Scans: Scout Scans W5 Axial scan location m Coreplugs 13

14 Mean porosity= 7.8% Mean porosity= 7.6% Mean porosity= 7.8% Mean porosity= 9.2% Mean porosity= 8.0% Mean porosity= 7.9% Mean porosity= 9.2% Mean porosity= 7.9% Mean porosity= 6.7% 14

N 2 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

N 2 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

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

N 2 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 From SPE Desorption analysis using BJH Theory 18

N 2 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

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

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

N 2 Adsorption/Desorption BJH Analysis (PSD) Effect of degas temperature 22

N 2 Adsorption/Desorption BJH Analysis (PSD) Comparison to Montney tight gas reservoir Permeability implications From Clarkson et al. AAPG Bulletin, in press 23

N 2 Adsorption/Desorption BET (Surface Area) Extension of Langmuir’s Theory to multilayer adsorption Very common method for surface area analysis From SPE Desorption analysis using BJH Theory 24

N 2 Adsorption/Desorption 25

N 2 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

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

SANS/USANS Analysis 28

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

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

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

SANS/USANS Fit of 1101A2 to PDSP model using PRINSAS 32

SANS/USANS 33

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