20 th Annual Williston Basin Petroleum Conference

1. 20th Annual Williston Basin Petroleum Conference Russ Buettner Bakken Asset Team Subsurface Manager Marathon Oil Corporation Bismarck, North Dakota May 23rd, 2012

2. Understanding Vertical & Horizontal Communication in the Bakken Agenda • Highlight Marathon’s Bakken results • Why are we focused on lateral and vertical communication? • Marathon’s Data Acquisition Overview • Observations that indicate communication • During both stimulation and production • Key data and analysis used to construct reservoir models • Calibrated simulation results that provide insight toward oil recovery potential • Invitation to Collaborate 2

3. Striving for Performance Improvement Industry Completion Practices (1,600 wells)* Marathon Oil Corporation MRO Per Well EUR by Year MRO Per Well Avg IP by Year 90 Day Cum Oil vsFrac Fluid* Recovery improvements have been made….but do we understand fundamentally why? * Source: NDIC database

4. 2006 – 2011 Dunn County Middle Bakken Wells 2006 – 2007 Open Hole Wells 2006 – 2007 Open Hole Completion Wells Average Proppant Density (lb/ft): 71 Why do more stages improve performance? -More uniform stimulation along the lateral -Increased Stimulated Rock Volume -Connections to bounding layers? 2008 Staged Wells 2008 Stage Completion Wells Average # of Stages: 6 Average Proppant Density (lb/ft): 144 2009 Staged Wells 2009 Stage Completion Wells Average # of Stages: 9 Average Proppant Density (lb/ft): 171 2010 Staged Wells 2010 Stage Completion Wells Average # of Stages: 19 Average Proppant Density (lb/ft): 268 2011 Staged Wells 2011 Stage Completion Wells Average # of Stages: 20 Average Proppant Density (lb/ft): 228 2011 staged wells cumulative oil production based on extrapolation.

5. What is the potential of the Entire Bakken section? Oil in place in at Typical 1280 acre DSU 40-60 MMBbls • 5-15% RF of MB or TF is what we attribute to a development unit • But is recovery limited to the horizon that the lateral is landed in?

6. Conceptual Single Well Recovery of All geologic layers vs. MB only Model cross-section 5,280ft 5,280 ft Broad areal drainage with no vertical connectivity Limited areal drainage with increased vertical connectivity UBS MB LBS TF MB High Side - Full Vertical Communication Low Side - Vertical Barriers constrain drainage to MB only • All geologic layers are connected through the natural fracture and fault network • Vertical drainage is more dominant than lateral • Well EUR40 : 900 – 1,100 MBOE • Geologic barriers between MB and TF and no drainage of bounding shales • Lateral drainage is dominant • Well EUR40 : 300 - 500 MBOE Geocellular model based simulation with dual porosity and discrete fracture network

7. Conceptual Full Development - What is Optimum Spacing? MB TF Optimum spacing depends on the degree of vertical drainage Full Vertical Communication Vertical Barriers • All geologic layers are connected through fracture networks • Total wells per DSU: 3 MB + 3 TF • DSU EUR40 : 4 - 6 MMBOE • MBWell EUR40: 700 – 1,000 MBOE • Geologic barriers between MB and TF. No recovery from shales • Total wells per DSU: 3 MB + 3 TF • DSU EUR40 : 2 – 3.5 MMBOE • MBWell EUR40: 200- 300 MBOE • Geologic barriers between MB and TF. No recovery from shales • Total wells per DSU: 5 MB + 5 TF • DSU EUR40 : 3 – 4.5 MMBOE • MBWell EUR40: 150- 250 MBOE

8. Core Facies Descriptions Sequence Stratigraphy Model Petrophysics Core fracture descriptions Fracture intensity[FI], orientation, relaxed apertures, morphology, kinematics Borehole image logs Fracture counts, orientations, apertures, in-situ stress Geophysics 3D/3C surface seismic VSP (ZO,WA,FO) & Microseismic Lineaments Grav & Mag attributes Surface Data (Landsat, Digital Elevation Model, etc) Geochemistry Rocks & Fluid Samples Production Data (Pre- & Post-Stimultation) In-Situ Stress (Vertical DFIT/FET, Pp, Shmin) Stimulation (Anomalous Stages, Inter-well Connectivity, Tracers in Vertical & Horizontal Wells) SCAL & Geomechanics Multiple Plug Orientations, Dynamic & Static Elastic Properties (Anisotropy & Tensors) Failure Data (MCFE) Permeabilities Bakken Data Acquisition & Integration Core Facies Descriptions & Petrophysics

9. Core Facies Descriptions Seq-Strat Model, Facies definition for mapping & modeling Petrophysics Core fracture descriptions Fracture intensity, orientation, aperture description Borehole image logs Fracture counts, orientations, apertures, in-situ stress Geophysics 3D/3C surface seismic VSP (ZO,WA,FO) & Microseismic Lineaments Grav & Mag attributes Surface Data (Landsat, Digital Elevation Model, etc) Geochemistry Rocks & Fluid Samples Production Data (Pre- & Post-Stimultation) In-Situ Stress (Vertical DFIT/FET, Pp, Shmin) Stimulation (Anomalous Stages, Inter-well Connectivity, Tracers in Vertical & Horizontal Wells) SCAL & Geomechanics Multiple Plug Orientations, Dynamic & Static Elastic Properties (Anisotropy & Tensors) Failure Data (MCFE) Permeabilities Bakken Data Acquisition & Integration Example of Core Description Vertical Core : Natural Fracture Intercept Rate (Fracture counts) & Fracture Morphology Fracture intensity Horizontal Core

10. Core Facies Descriptions Seq-Strat Model, Facies definition for mapping & modeling Petrophysics Core fracture descriptions Fracture intensity[FI], orientation, relaxed apertures, morphology, kinematics Borehole image logs Fracture counts, orientations Geophysics 3D seismic & VSP’s Microseismic Lineaments Grav & Mag attributes Surface Data (Landsat, Digital Elevation Model, etc) Geochemistry Rocks & Fluid Samples Production Data (Pre- & Post-Stimultation) In-Situ Stress (Vertical DFIT/FET, Pp, Shmin) Stimulation (Anomalous Stages, Inter-well Connectivity, Tracers in Vertical & Horizontal Wells) SCAL & Geomechanics Multiple Plug Orientations, Dynamic & Static Elastic Properties (Anisotropy & Tensors) Failure Data (MCFE) Permeabilities Bakken Data Acquisition & Integration Horizontal Image Logs & 3D Fracture Corridors from Seismic (curvature calibrated to image Log)

11. Core Facies Descriptions Seq-Strat Model, Facies definition for mapping & modeling Petrophysics Core fracture descriptions Fracture intensity[FI], orientation, relaxed apertures, morphology, kinematics Borehole image logs Fracture counts, orientations, apertures, in-situ stress Geophysics 3D/3C surface seismic & VSP’s Microseismic Lineaments Grav & Mag attributes Surface Data (Landsat, Digital Elevation Model, etc) Geochemistry Rocks & Fluid Samples Production Data (Pre- & Post-Stimultation) In-Situ Stress (Vertical DFIT/FET, Pp, Shmin) Stimulation (Anomalous Stages, Inter-well Connectivity, Tracers in Vertical & Horizontal Wells) SCAL & Geomechanics Multiple Plug Orientations, Dynamic & Static Elastic Properties (Anisotropy & Tensors) Failure Data (MCFE) Permeabilities Bakken Data Acquisition & Integration

12. Core Facies Descriptions Seq-Strat Model, Facies definition for mapping & modeling Petrophysics Core fracture descriptions Fracture intensity[FI], orientation, relaxed apertures, morphology, kinematics Borehole image logs Fracture counts, orientations, apertures, in-situ stress Geophysics 3D/3C surface seismic VSP (ZO,WA,FO) & Microseismic Lineaments Grav & Mag attributes Surface Data (Landsat, Digital Elevation Model, etc) Geochemistry Core , Cuttings & Produced Fluid Samples Production Data (Pre- & Post-Stimultation) In-Situ Stress (Vertical DFIT/FET, Pp, Shmin) Stimulation (Anomalous Stages, Inter-well Connectivity, Tracers in Vertical & Horizontal Wells) SCAL & Geomechanics Multiple Plug Orientations, Dynamic & Static Elastic Properties (Anisotropy & Tensors) Failure Data (MCFE) Permeabilities Bakken Data Acquisition & Integration

13. Core Facies Descriptions Seq-Strat Model, Facies definition for mapping & modeling Petrophysics Core fracture descriptions Fracture intensity[FI], orientation, relaxed apertures, morphology, kinematics Borehole image logs Fracture counts, orientations, apertures, in-situ stress Geophysics 3D/3C surface seismic VSP (ZO,WA,FO) & Microseismic Lineaments Grav & Mag attributes Surface Data (Landsat, Digital Elevation Model, etc) Geochemistry Rocks & Fluid Samples Production Data (Pre- & Post-Stimultation) In-Situ Stress (DFIT/FET) Stimulation (Anomalous Stages, Inter-well Connectivity, Tracers in Vertical & Horizontal Wells) SCAL & Geomechanics Multiple Plug Orientations, Dynamic & Static Elastic Properties (Anisotropy & Tensors) Failure Data (MCFE) Permeabilities Bakken Data Acquisition & Integration

14. Core Facies Descriptions Seq-Strat Model, Facies definition for mapping & modeling Petrophysics Core fracture descriptions Fracture intensity[FI], orientation, relaxed apertures, morphology, kinematics Borehole image logs Fracture counts, orientations, apertures, in-situ stress Geophysics 3D/3C surface seismic VSP (ZO,WA,FO) & Microseismic Lineaments Grav & Mag attributes Surface Data (Landsat, Digital Elevation Model, etc) Geochemistry Rocks & Fluid Samples Production Data (Pre- & Post-Stimultation) In-Situ Stress (Vertical DFIT/FET, Pp, Shmin) Stimulation (Anomalous Stages, Inter-well Connectivity, Tracers in Vertical & Horizontal Wells) Special core analysis Geomechanical rock properties Matrix Permeabilities from whole core Bakken Data Acquisition & Integration Shear Stress (psi) Increases Normal stress (psi) Increases

15. Increased well density Preparing for and observing lateral communication during fracsDecompleting offset wells during fracs Offset Lateral Distances to Frac’d Lateral Gas Profile for Frac’d Lateral • Probable fracture corridors interpreted from gas shows and structure maps • Seismic is also helpful in detecting larger structural events Natural Fracture Interpreted ~50% of Near offset decompleted wells see pressure from offet stimulation treatments “Probable” Fracture Corridors Fracture Corridor N High Natural Fracture Density Assumed Structure from well data Infill Wells 2000’ Radius 3000’ Radius Curvature Map Suggestive of Natural Fracture Density Low Natural Fracture Density Assumed

16. Completion Interference: Three Forks to Middle Bakken Three Forks Frac Pressures Up Offset MB Well Via Fracture Corridors? • Casing pressure in a Middle Bakken well increased from 75 to 3000 psi during stimulation of adjacent TF well • Pressure increases correlated with stages located in areas with high gas shows in the lateral Three Forks Lateral Middle Bakken Well Middle Bakken Lateral Middle Bakken Casing Pressure 700’ Fracture Corridors Middle Bakken Well Three Forks Lateral Stage Number Infill wells Three Forks Well Three Forks Well

17. Production Interference – Middle Bakken interferes with Three ForksVertical Communication Occurs Through Natural Fractures? Middle Bakken well Three Forks well Three Forks well Lodgepole Middle Bakkenwell Instantaneous production interference between nearby MB and TF wells Upper Bakken Shale Middle Bakken well Pump installation Middle Bakken Lower Bakken Shale Three Forks Middle Bakken well 250 ft 500 ft Three Forks well Production communication Three Forks well

18. Horizontal Core Vertical Fractures in a Horizontal Cores Wide aperture fluorescing fractures in intact core Slabbed Core Horizontal Core Slab revealed intense fabric of micro-fractures Core Depth Increases Core Depth Increases 18

19. Outcrops and Conceptual fracture models help explain communication observed in the field Bed contained fractures • Fractures related to faults can penetrate geologic units • Vertical drainage through fault related fractures should be expected General outcrop display– not Middle Bakken

20. Integrating natural fractures into a 3 dimensional geocellular model -Description of pervasive micro-fracture network Regional Fractures - Description of Regional Fractures Structural Fractures ShMax -Inclusion of structurally related fractures (swarms-corridors) Characterization and understanding of all fractures both natural and induced is needed to predict performance Independent Fracture properties are included in a dual porosity simulation.

21. Vertical Stress and Hydraulic Fracture ModelIntegrating field data to understand fracture growth INCREASING • Vertical stress and pore pressure in 5 layers (LP, UBS, MB, LBS and TF) were measured with DFIT tests • Results used as inputs to hydraulic fracture simulation models • Note marginal differences in pore pressure in each layer that also suggests that the layers are in communication INCREASING • Predictive fracture models indicate containment of fracs within zone • The created Xf that can exceed 1,000’, but the effective, propped fracture half-lengths are <200’ • Model does not include natural fracture description that can divert fracture growth vertically LP MB TF

22. Geochemical Data - Stratigraphic intervals in the Bakken Petroleum System have unique geochemical fingerprints • Geochemical signature values can be sampled initially and over time • Fluctuation would be indicative of contribution from bounding layers Geochemical Signature

23. Individual Well Reserve Evaluations – Which b-factor?Decline analysis also suggests vertical communication is occuring • Full vertical communication • In this model, geologic units are connected vertically through fracture networks • Simulation indicates that b-factors would stabilize near 2. • Vertical barriers between layers • With no vertical communication between layers in the model • Simulation indicates that b-factors will stabilize at around 1.0 (isolated MB well) • This behavior is not being observed in areas studied Well performance observations are between these two cases indicating partial vertical communication

24. Example - Calibrated Single Well Conceptual Model Pressure depletion from a frac stage and through natural fractures Vertical Permeability resulting from fracture networks • Vertical communication is modeled to occur through structurally related fractures • Vertical contribution is calibrated with geochemical based production allocation • Propped hydraulic fractures are assumed to be contained in MB • EUR40 : 600 -850 MBOE History matching and geochem production allocation helps to understand how to constrain vertical communication in the static model

25. Challenge – How do we collaborate as developers of the Bakken to improve efficiency and oil recovery? 30 years depletion Pressure (Fracture Grid) TF MB TF MB Acreage positions are secure in many areas Sharing technical understanding and best practices will serve North Dakota and all of the Bakken stakeholders

26. Acknowledgments • Marathon Bakken Asset team • Doyle Adams • Faisal Rasdi • Ahmad Salman • Upstream Technology – Bakken Integrated Reservoir Characterization Team • Sebastian Bayer • Steve Buckner • Jason Chen • Phillipe Lozano