Geologic Analysis of Naturally Fractured Reservoirs 2nd Edition, R. A Geologic Analysis of Naturally Fractured Reservoirs 2nd Edition, R.A. Nelson (2001) Gulf Professional Publishing a subsidiary of Butterworth-Heinemann, Boston, MA

Geologic Analysis of Naturally Fractured Reservoirs 2nd Edition, R. A Geologic Analysis of Naturally Fractured Reservoirs 2nd Edition, R.A. Nelson (2001) The following contains renditions of the figures included within the book as well as additional figures used by the author to teach industry courses on the subject. Also included is Appendix D of the book.

Ronald A. Nelson Discipline Structural Geology & Rock Mechanics Location BP Amoco, Upstream Technology, Geology Team, Houston History 26 years with BP Amoco as Specialist & Manager Education BS (Northern Illinois), MS, PhD (Texas A&M) all in Geology Skills Fractured Reservoirs, Technology Management, Peer Assists, Recruiting, Structural Interpretation in Thrust Belts and Rifts Publications 75 citations; including a textbook “Geologic Analysis of Naturally Fractured Reservoirs” eds. 1&2.

Liesegang Banding in Aztec Ss, Nevada

Work Builds On: Nelson, R. A., 1985, Geological Analysis of Naturally Fractured Reservoirs: Contributions in Petroleum Geology & Engineering, Gulf Publishing Co., Houston, TX, 320 p. Material presented in the AAPG Fractured Reservoir Analysis School, 1984-1996.

Courtesy of Gulf Professional Publishing, Boston

General Outline Introduction Fracture Origin Fracture Morphology Fracture Porosity Fracture Permeability F/M Interaction Fracture Intensity Intensity Prediction 9. Orientations 10. Reservoir Types 11. Well Directions 12. Simulation 13. Fracture Reservoir Production 14. Reservoir Screening 15. Summary (Field Examples)

Reasons Why We Look at Natural Fractures Delineate Structure Determine Mode & Path of Deformation Define Mechanics of Fracture Determine Paleo-stress Directions Determine Velocity Anisotropy Determine Mechanical Anisotropy Predict Reservoir Properties & Potential

Total Integration Includes: Fracture system characterization Stratigraphic interpretation & modeling Structural geology Petrophysics Seismic mapping & attribute analysis Well testing, inc. production logs Production history matching Reservoir engineering, inc. dual porosity flow behavior Fracture scaling and reservoir simulation Drilling and completion technology

Modeling in Fractured Reservoirs SPE Forum, Sept. 2000 Static Conceptual Model Dynamic Conceptual Simulation Static Description Dynamic Description Upscaling Subsurface Outcrop Wellbore Geophysics Pressure Temperature Fluid Types Energy Full Static & Dynamic Simulation Sanction, Recovery Planning, Flood Design, etc. Statistical & Geomechanical Representation Well Test Data & Well Histories Modeling in Fractured Reservoirs SPE Forum, Sept. 2000 Oil Water Hansen Peng Rawnsley Derivative Experience & Analogs Discrete Model Continuous Model Nelson

Fundamental Approach after Nelson (1985) Determine fracture system origin(s) in 3-d Allows for predictability away from wellbore Tectonic, regional, cleat, diagenetic, sequence Determine reservoir properties & var. in 3-d Quantifies porosity, permeability, etc. Morphology, width, spacing/intensity, stress affects Fracture/matrix communication Linkage in dual porosity system Cross flow, connectivity, recovery

Fundamental Approach (cont.) Determine reservoir type Defines relative contribution of fractures and problems Simulation, production character, management Locate optimum drill locations & well paths Quantifies “sweet spots” & maximizes wellbore surface Intensity, azimuth, directional drilling, seismic attributes Develop reservoir management strategies Control the reservoir to efficiently balance rate & recovery and reduce well costs Fracture closure, well patterns, sweep

Recent Advancement Areas Log Characterization Spacing Estimates Fracture Zone Identification Reservoir Simulation Azimuth Predictions Reservoir Analogs Effects of Fracture and Diagenetic History

Impacts on Fractured Reservoir Studies

Fracture A macroscopic planar discontinuity in rock which is interpreted to be due to deformation or physical diagenesis It may be due to compactive or dilatent processes, thus having either a positive or negative effect on fluid flow Its characteristics may have been modified by subsequent deformation or diagenesis

Fractured Reservoir Any reservoir in which naturally occurring fractures have, or are predicted to have, a significant effect of flow rates, anisotropy, recovery, or storage.

Avoid “Fracture Denial”

“Fracture Denial” Keeps Us From: Gathering important static data early Optimizing our well locations & paths Designing our secondary recovery patterns correctly Accurately predicting field rates & recovery Economically depleting our field