Comparison of the Recovery Behavior of Contrasting Reservoir Analogs in the Ferron Sandstone Using Outcrop Studies

RI0249. Comparison of the Recovery Behavior of Contrasting Reservoir Analogs in the Ferron Sandstone Using Outcrop Studies and Numerical Simulation, by C. D. White and M. D. Barton. 46 p., 40 figs., 4 tables, 1998. Print.

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ABSTRACT
Fluvial-deltaic reservoirs contain large volumes of oil and gas. These reservoirsandstones may have complex stacking patterns, and shales or very fine grained sandstone may form baffles or barriers to flow. As a result, significant compartmentalization or baffling may occur in fluvial-deltaic reservoirs. Because of their close analogy with reservoirs in the Gulf of Mexico region, outcrops of Ferron Sandstone in central Utah have been used to investigate the heterogeneity and possible recovery behavior of high-accommodation fluvial-deltaic reservoirs.

Two outcrop data sets were prepared for numerical reservoir simulation using new editing, ordering, and discretization methods. These simulation models use cornerpoint geometries and reproduce important aspects of bedding geometry, shale distribution, and facies patterns. Reservoir simulation was used to investigate the flow behavior of fluvial-deltaic reservoirs, using a commercial black oil simulator to simulate tracer displacements, gas depletion, and gas-water displacements.

This analysis shows that fluvial-deltaic reservoirs from different sequence stratigraphic settings may have significantly different production characteristics. The unswept zones within landward-stepping tongues tend to be less continuous than the unswept zones within the seaward-stepping tongues.

Keywords: Ferron Sandstone, fluvial-deltaic, reservoir characterization, reservoir simulation, Utah

CONTENTS
Abstract
Introduction
      Combining Interpretation, Characterization, Modeling, and Prediction
      Background
      Approach
      Goals
Geologic Setting of the Ferron Sandstone
     Approach
     Geologic Setting
Background for Numerical Reservoir Simulation
     Description of Numerical Reservoir Simulation Models and Methods
     Use of a Cornerpoint Geometry Grid
     Recovery Processes, Flow Modeling, and Reservoir Characterization
          Ideal Tracer Displacement
          Pure Depletion Drive
          Gas-Water Displacements
     Transforming Outcrop Data into Gridded Simulation Models
     The Importance of Structure
     Preserving Geometry
     Reservoir Simulation
     Computational Issues
          Computing Block Properties
          Grid Orthogonality
          Numerical Constraints and Artifacts
Description and Flow Modeling of the Ferron Sandstone Outcrops
     Picture Flats, a Landward-Stepping Tongue
          Geological Background for the Picture Flats Outcrop
          Model Description for the Picture Flats Outcrop
          Simulation Results for the Picture Flats Outcrop
                Ideal Tracer Displacement
                Pure Depletion Drive
                Gas-Water Displacements
      Interstate 70, a Seaward-Stepping Tongue
           Geological Background for the Interstate 70 Outcrop
           Model Description for the Interstate 70 Outcrop
           Simulation Results for the Interstate 70 Outcrop
                 Ideal Tracer Displacement
                 Pure Depletion Drive
Comparison of Flow Behavior
Geological Recapitulation
Tracer Flow and Sweep Efficiency
Gas Recovery
Interpreting Two-Dimensional Results
Conclusions and Recommendations
     Conclusions
     Recommendations
Acknowledgments
References
Nomenclature

Figures

1. Cross section of Cretaceous strata in central Utah
2. Schematic cross section of Ferron Sandstone in central Utah
3. Line diagram showing the bedding geometry within the valley fill at the Interstate 70 outcrop of the Ferron Sandstone
4. Regular Cartesian ordering for a two-dimensional simulation grid
5. A two-dimensional, Cartesian-ordered cornerpoint geometry simulation grid
6. Flow chart of the data conversion process
7. Diagram showing order relations to be corrected by a surface editing program
8. Sketch of the surface-ordering algorithm
9. Hierarchical data structure at Picture Flats outcrop
10. Hierarchical data structure at Interstate 70 outcrop
11. Model of pinch-outs
12. Map of Ferron Sandstone outcrop in central Utah showing location of study area and detailed case studies
13. Index map showing location of vertical transects from Picture Flats case study site, cycle 5
14. Cross section depicting facies architecture and permeability profiles, cycle 5, Picture Flats, a landward-stepping unit
15. Photograph of outcrop between sections 5 and 6 of the Ferron Sandstone
16. Box plot of permeability versus grain size, Picture Flats, cycle 5, Ferron Sandstone
17. Facies map displaying horizontal permeability assigned to the simulation grid for the Picture Flats outcrop
18. Gridded image of the permeability of the Picture Flats outcrop using a flat style of refinement
19. Model of shales using transmissibility multipliers
20. Grid of the Picture Flats outcrop showing departure from orthogonality
21. Tracer distribution for the Picture Flats model
22. Tracer breakthrough for the Picture Flats model
23. Tracer sweep for the Picture Flats model
24. Pressure distribution for the Picture Flats model
25. Gas recovery for the Picture Flats model
26. Water displacing gas in the Picture Flats model
27. Index map showing location of vertical transects from lnterstate 70 case study site, cycle 2
28. Facies architecture and permeability profiles, lnterstate 70, Ferron Sandstone, cycle 2
29. Photograph of Interstate 70 outcrop near section 1
30. Photograph of Interstate 70 outcrop between sections 9 and 12
31. Box plot of permeability versus facies, Interstate 70, cycle 2, Ferron Sandstone
32. Permeability grid of the Interstate 70 outcrop
33. Permeability grid for the Interstate 70 outcrop using no refinement
34. Grid of the Interstate 70 outcrop showing departure from orthogonality
35. Vertical transmissibility multipliers for the Interstate 70 model
36. Tracer distribution for the Interstate 70 model
37. Tracer breakthrough for the Interstate 70 model
38. Tracer sweeps for the Interstate 70 model
39. Pressure distribution for the Interstate 70 model
40. Gas recovery for the Interstate 70 model

Tables

1. Facies properties for the Picture Flats outcrops

2. Properties of simulation grids for the Picture Flats and Interstate 70 outcrops

3. Simulation results summary for Picture Flats and Interstate 70 outcrops

4. Facies properties for the Interstate 70 outcrop


Citation
White, C. D., and Barton, M. D., 1998, Comparison of the Recovery Behavior of Contrasting Reservoir Analogs in the Ferron Sandstone Using Outcrop Studies and Numerical Simulation: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 249, 46 p.