Geological Characterization of the Surmont Caprock Interval. John R. Suter Oil Sands ConocoPhillips Canada

Transcription

1 Geological Characterization of the Surmont Caprock Interval John R. Suter Oil Sands ConocoPhillips Canada

2 Acknowledgements I ConocoPhillips Canada TOTAL Exploration & Production Canada ConocoPhillips Canada Tim Tomberlin Tim Crowther Joy Ishigo** Doris Ross Daniel Kittridge Scott Robinson Lori Dwyer ConocoPhillips Subsurface Technology Houston Thomas Demchuk Thomas Neely Peter D Onfro Bruce Hart Jennifer Adams Courtney Turich Ron Waszczak

3 Acknowledgements II Academic Partners Rick Chalaturnyk, University of Alberta Joe Macquaker, Memorial University of Newfoundland Vendors TarCore Labs (core photography, description, & analyses) Biostratigraphy Graham Dolby & Associates Palynology Claudia Schroeder-Adams, Carleton University - Forams David Rutledge, Petrostrat Ltd. - Calcareous nanofossils ConocoPhillips Bartlesville laboratory - XRD Chemostrat Inc - Chemostratigraphy (bulk chemistry) Fugro Robertson QEMScan SGS Canada QEMScan, XRD (mineralogy)

4 Conclusions The caprock interval at Surmont comprises laterally continuous successions of fair to world-class top seals Sequence Stratigraphy, Depositional Environments, and Lithologies Lithology is a succession of clays, silts, and very fine sands Depositional environments comprise distal deltaic, shoreface, and shelf deposits At least three depositional sequences are present with the caprock interval* Caprock Interval has been characterized by a variety of different techniques Sequence Stratigraphy & Lithofacies-Depositional Enviroments Seismic Structural Analysis Biostratigraphy (Palynology, foraminifera, calcareous nanofossils) Quantitative Mineralogy (QEMScan ) Clay Mineralogy (X-ray Diffraction) Inorganic bulk chemistry (Chemostratigraphy)

5 Outline Introduction & Stratigraphic Framework Quaternary Channeling Seismic Structural Analysis Sequence Stratigraphy & Depositional Environments Analytical Results & Integration Conclusions

6 ConocoPhillips Oil Sands Properties Surmont

7 Surmont Caprock Interval W400 Clearwater Marker Top Wabiskaw Wabiskaw-McMurray Marker Top McMurray Caprock Interval Devonian Unconformity

8 Database: Cores, Logs, and Seismic

9 Stratigraphic Succession Upper GR FS Lower GR FS Caprock Clearwater Marker Top Wabiskaw Top McMurray/Wabiskaw McMurray Marker Reservoir Devonian (SubCretaceous Unconformity)

10 Interval Thickness Map

11 Elevation, hence overburden, varies over the Surmont Lease. Overburden Variation

12 Quaternary Bedrock Topography Quaternary Incision is not a threat to caprock integrity at Surmont Data from ERCB and AGS

13 SubCretaceous Unconformity Regional Unconformity Map Time Structure Map on Unconformity at Surmont Surmont

14 Seismic Structural Analysis Fault-enhance volume attribute, extracted on horizons linear & curvilinear discontinuities present, particularly at Devonian unconformity discontinuities not through-going Top McMurray reservoir SubCretaceous Unconformity

15 Wells Analyzed

16 Chronostratigraphy Chronostratigraphy Previous studies on the McMurray Formation suggested an age as young as early Albian Unconformably(?) overlain by the early/middle Albian Wabiskaw Member Foraminiferal ages based on circular reasoning(?) Current palynological data suggest the McMurray Formation could be of early to middle Aptian in age Wabiskaw could be as old as latest Aptian Recent analyses of foraminifera and calcareous nanofossils were inconclusive (forams) or unsuccessful (nanofossils; barren): currently being investigated for siliceous microfossils

17 Athabasca Palynology (redrawn from Demchuk et al, 2007; redrawn from Michoux, 2002)

18 Athabasca Palynofacies Palynofloral assemblages and designations Palynofloral continuum from freshwater, through brackish into restricted/marginal marine paleoenvironments Assemblages overlap and content is gradational Fresh to brackish = McMurray Brackish to marginal/restricted marine = Wabiskaw/Clearwater Classification scheme is evolving as additional areas/samples from the McMurray/Wabiskaw/Clearwater are investigated 18 (used with permission from Dolby, 2010)

19 Palynology 1AA W400 Clearwater Marker MFS2 Top Wabiskaw Wabiskaw-McMurray Marker Top McMurray (used with permission from Dolby, 2010)

20 Paleobathymetry

21 Schematic Sequence Stratigraphy SW Clearwater Marker MFS2 Top Wabisakw Wab McM. mrkr Top McMurray Stacked Succession of Shoreface/Deltaics Shelves and Incised Valleys B C AC Abandoned Channel Wabiskaw D MFS MFS Wabiskaw D D Gas SB Wabiskaw B Facies Change in upper Point Bar IHS FS/SB SB S Caprock Interval Top Water NE Devonian Unconformity Sandy Amalgamated Bars SB SB SB AC SB Bitumen Occupies Topographic Lows in Devonian Basal Shale Distal marine parasequence within Clearwater Formation Marine parasequences within Clearwater Marine parasequences within Wabiskaw Wabiskaw D strata Top Water in McMurray Formation; IHS Gas accumulations in McMurray, Wabiskaw D Bitumen reservoir within the McMurray Formation Abandoned Channel Fill within the McMurray Formation Basal Shale undifferentiated non-reservoir deposits within McMurray Formation

22 Sequence Stratigraphic Analysis of Well Logs: Basic Stacking Patterns Stacking patterns refer to the vertical and lateral arrangement of beds, bedsets, parasequences, parasequence sets, sequences, and sequence sets. These figures illustrate the basic parasequence stacking types and their use in sequence stratigraphic analysis on simulated gamma-ray logs. PROGRADATIONAL AGGRADATIONAL RETROGRADATIONAL (Regressive, Seaward - Stepping) (Backstepping, Transgressive, Landward-Stepping) Thicker, less shaly upward Sediment source moving closer (regression) Typical of HIGHSTAND systems tract Similar thickness, shaliness Sediment source maintained nearby Typical of LOWSTAND systems tract Upward thinning, shalier Sediment source moving away (transgression) Typical of TRANSGRESSIVE systems tract

23 Sequence Stratigraphic Analysis of Well Logs: Interpretations of Stacking Patterns Idealized parasequence stacking patterns of a complete marginal marine depositional sequence Maximum Flooding Surface "Transgressive" Surface Sequence Boundary Highstand: Progradational Transgressive: Retrogradational Lowstand: Aggradational Highstand: Progradational Changes in these patterns can be used for sequence stratigraphic interpretation and correlation Sequence Boundary Incised Valley TST LST/TST TST LST Highstand is missing, probably eroded away TST HST TST LST Lowstand is missing, probably an interfluve Flooding Surface/ Sequence Boundary Maximum Flooding Surface

24 Stacking Pattern Analysis: Some Potential Pitfalls Lateral shifts in sediment sources, i.e., delta switching and/or river avulsion Strike view: Laterally shifting depocenters Apparent backstepping Apparent backstepping Apparent progradation Dip view: Progradation 2. Continued progradation, lateral shift in depocenter 3. Continued progradation, depocenter moves closer 4. Relative sea level rise, depocenter moves landward Apparent aggradation Apparent backstepping, progradation Apparent Backstepping

25 Sequence Stratigraphic Framework MFS Clearwater MFS Wabiskaw FS-SB MFS McMurray

26 W400 MFS2 MFS

27 W400

28 Ichnology Ichnology of the caprock interval (redrawn from Pemberton et al, 2001)

29 Depositional Environments: Lower Shoreface - Shelf Foreshore Upper Shoreface Lower Shoreface Inner Shelf Surmont CI depositional environments (redrawn from Howell et al, 2005)

30 Shoreface-Shelf Deposition Surmont CI depositional environments (redrawn from Swift et al, 1991)

31 QEMScan Technique (used with permission from SGS, 2011)

32 QEMScan Images W m Clearwater Sand Main Minerals: Quartz, Fe-Illite & illitesmectite, Smectite Minor Minerals: K Feldspar, Plagioclase, Muscovite, Kaolinite, Chlorite, Illite & illitesmectite, Glauconite, Dolomite, Ferroan Dolomite, Siderite m Clearwater Marker Main Minerals: Quartz, Illite & illitesmectite, Fe-Illite & illite-smectite, Smectite Minor Minerals: Pyrite Mud (used with permission from SGS, 2011)

33 1AA W400 Whole Rock Mineralogy Clearwater Wabiskaw Wabiskaw-D McMurray

34 1AA W400 Total Clay Clearwater Clearwater Marker Caprock_MFS2 Wabiskaw Top Wabiskaw Wab-McMurray Marker Wabiskaw-D Top McMurray McMurray

35 1AA W400 Clay Species Clearwater Clearwater Marker Caprock_MFS2 Wabiskaw Top Wabiskaw Wabiskaw- McMurray Marker Wabiskaw-D Top McMurray McMurray

36 Chemostratigraphy Chemostratigraphy = Whole Rock (Bulk) Elemental Analysis Inorganic Geochemistry Conclusions: The lithostratigraphic units encountered over the study intervals of the four wells analysed from the Surmont property, namely the McMurray, Wabiskaw and Clearwater Formations, each have their own distinctive geochemical characteristics, thereby enabling them to be easily differentiated from geochemical evidence alone. Five chemostratigraphic packages have been defined These compare favorably with the units derived from sequence stratigraphy, mineralogy, and palynology

37 Chemostratigrapy 1AA W400 Clearwater Clearwater Marker MFS2 Package 5 Package 4 Wabiskaw McMurray Top Wabiskaw Wab-McMurray Marker Top McMurray Package 3 Package 2 Package 1 (used with permission from Chemostrat, Inc, 2011)

38 Elements of Top Seal Seal capacity, as measured by mercury displacement pressure, measures the height of a hydrocarbon column that can be supported by the lithology at the site of the seal sampled Integrity refers to the susceptibility of the seal to breaching by fracturing or faulting Continuity delineates the areal extent, thickness, and facies variations of a given seal Important controls: lithology (% sand, silt, clay), clay mineralogy, grain size distribution;, grain fabric, diagenesis; burial history Initial seal quality is a function of depositional environments and sequence stratigraphy

39 Conclusions The caprock interval at Surmont comprises laterally continuous successions of fair to world-class top seals Sequence Stratigraphy, Depositional Environments, and Lithologies Lithology is a succession of clays, silts, and very fine sands Depositional environments comprise distal deltaic, shoreface, and shelf deposits At least three depositional sequences are present with the caprock interval* Caprock Interval has been characterized by a variety of different techniques Sequence Stratigraphy & Lithofacies-Depositional Enviroments Seismic Structural Analysis Biostratigraphy (Palynology, foraminifera, calcareous nanofossils) Quantitative Mineralogy (QEMScan ) Clay Mineralogy (X-ray Diffraction) Inorganic bulk chemistry (Chemostratigraphy)