Geologic and Engineering Characterization of Turbidite Reservoirs, Ford Geraldine Unit, Bell Canyon Formation

RI0255. Geologic and Engineering Characterization of Turbidite Reservoirs, Ford Geraldine Unit, Bell Canyon Formation, West Texas, by S. P. Dutton, M. D. Barton, G. B. Asquith, M. A. Malik, A. G. Cole, John Gogas, J. I. Guzman, and S. J. Clift. 88 p., 74 figs., 7 tables, 1999. Print.

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About This Publication
This report summarizes results of an integrated geological, geophysical, petrophysical, and engineering study of a representative Delaware Mountain Group field to identify constraints on producibility in the deep-water sandstone reservoir exhibiting low primary recovery efficiency. The Ramsey sandstone interval of the Bell Canyon Formation was characterized in the Ford Geraldine unit, Culberson and Reeves Counties, Texas, using data from outcrops, subsurface logs and cores, and a 3-D seismic survey. Facies relationships determined from depositional processes interpreted from outcrop analogs exposed in Culberson County suggest that the sandstones were deposited by turbidites in a basin-floor system of channels and levees having attached lobes. The depositional model developed from outcrop can be widely applied by operators to other reservoirs that produce from Delaware sandstone. The study was funded primarily by the U.S. Department of Energy and the State of Texas.

ABSTRACT
Because reservoirs in deep-water sandstones of the Delaware Mountain Group in West Texas and New Mexico are characterized by low primary recovery efficiency (<14 percent), an integrated geological, geophysical, petrophysical, and engineering study of a representative Delaware Mountain Group field was performed to identify constraints on producibility. Characterization of the Ramsey sandstone interval of the Bell Canyon Formation was conducted in the Ford Geraldine unit, Culberson and Reeves Counties, Texas, using data from outcrops, subsurface logs and cores, and a 3-D seismic survey.

Outcrop analogs exposed in Culberson County, Texas, were studied to interpret the depositional processes that formed the reservoirs at the Ford Geraldine unit better and to determine the dimensions of reservoir sandstone bodies. Facies relationships suggest that the sandstones were deposited by turbidites in a basin-floor system of channels and levees having attached lobes that initially prograded basinward, aggraded, and then turned around and stepped back toward the shelf.

The 0- to 60-ft-thick Ramsey sandstone interval in the Ford Geraldine unit is interpreted as a channel-levee and lobe system similar to the one described in outcrop. Lobe deposits consist of massive and convoluted sandstones having load and dewatering structures, suggesting that the sandstones were deposited rapidly from high-density turbidity currents. Channel facies, approximately 1,200 ft wide and 15 to 35 ft thick, overlie and locally incise the lobe deposits. They consist of massive and crossbedded sandstones interpreted to have been deposited from high-density turbidity currents. Channel margins, characterized by rippled and convoluted sandstones interbedded with siltstones, are interpreted as channel levees formed by overbanking of low-density turbidity currents. Ramsey sandstones are bounded by laterally continuous, organic-rich siltstones deposited by settling from suspension. Siltstone beds and extensively calcite cemented sandstones are the most important causes of reservoir complexity.

Petrophysical characterization of the Ford Geraldine unit was accomplished by integrating core and log data and quantifying petrophysical properties from wireline logs. Net-pay cutoffs of 215 percent porosity (for permeability of 1 md), 160 percent water saturation, and 515 percent volume of clay were established. Water saturations were calculated by the following modified Archie equation: S, = [(I/0) x (Rw/R,)]l'l.90. The petrophysical data were used to map porosity, permeability, net pay, water saturation, mobile oil saturation, and other reservoir properties. Interpretation of the 3-D seismic volume indicates that Ramsey sandstone thickness in the Ford Geraldine unit is one-fourth of a wavelength of the seismic data or less and is therefore considered a thin bed. The coherency cube was effective in delineating the field outline but failed to detect reservoir compartmentalization. A residual map of the seismic horizon corresponding to the top of the Lamar limestone identified a residual high that is associated with Ramsey sandstone thickness.

An area in the north part of the unit that has not undergone tertiary development was chosen for reservoir modeling/simulation. Flow simulations were performed for a CO₂ flood to estimate the tertiary recovery potential of the area. Results indicate that 10 to 30 percent (1 to 3 million barrels [MMbbl]) of the remaining oil in the area can be produced by CO₂ injection.

Keywords: Bell Canyon Formation, deep-water sandstones, Delaware Basin, reservoir characterization, turbidites

CONTENTS

ABSTRACT

INTRODUCTION

GEOLOGIC SETTING

             Stratigraphic Framework

             Delaware Sandstone Oil Play

 OUTCROP CHARACTERIZATION OF BELL CANYON SANDSTONE RESERVOIR ANALOGS

             Introduction

             Models of Basinal Sandstone Deposition

             Facies

             Depositional Elements  

             Willow Mountain Case Study     

             Depositional Interpretation        

             Conclusions     

 RESERVOIR CHARACTERIZATION OF FORD GERALDINE UNIT

             Ramsey Sandstone Facies

                         Mapping of Genetic Units

                         Upper Ford Siltstone

                         Ramsey 1 Sandstone

                         SH1 Siltstone

                         Ramsey 2 Sandstone

                         Lower Trap Siltstone

Distribution of Facies

                         Channel Facies

                         Levee Facies

                         Lobe Facies

                         Laminated Siltstone Facies

                         Lutite Facies

 Proposed Depositional Model for Ford Geraldine Unit   

 Ramsey Sandstone Diagenesis

                         Methods          

                         Petrography of Ramsey Sandstones     

                         Diagenetic Controls on Reservoir Quality           

 PETROPHYSICS OF THE RAMSEY SANDSTONE

             Porosity Transforms

             Calculation of Water Saturation

                         True Formation Resistivity

                         Archie Parameters m and n

             Net-Pay Cutoffs

             Porosity Distribution

             Permeability Distribution

             Saturation Distribution

             Net Pay

 GEOPHYSICAL INTERPRETATION OF THE RAMSEY SANDSTONE
            Design and Processing

             Synthetic Seismograms and Wavelet Extraction

             Structure, Amplitude, and Coherency Maps

             Correlation Coefficients and Cross Plots

             Conclusions

FIELD DEVELOPMENT HISTORY

             Primary Recovery

             Secondary Recovery

             Tertiary Recovery

             Reservoir Heterogeneity and Production Constraints

 ESTIMATE OF TERTIARY RECOVERY POTENTIAL

             Estimate of Tertiary Recovery from Production Data

             Simulations of Tertiary Recovery

                         Simulation Results

                         Sensitivity Study

                         Improving Tertiary Recovery in the Stage 5 Area

CONCLUSIONS

ACKNOWLEDGMENTS

REFERENCES

Figures

1. Map showing location of the Ford Geraldine unit and outcrop study area in the Delaware Basin and paleogeographic setting during the Late Permian

2. Stratigraphic nomenclature of the Delaware Mountain Group in the Delaware Basin subsurface and outcrop areas and time-equivalent formations on the surrounding shelves

3. Production from the Geraldine Ford and other upper Bell Canyon fields in the Delaware Basin from the distal (southwest) ends of east-dipping, northeast-oriented linear trends of thick Ramsey sandstone deposits

4. Structure contours on the top of the Lamar limestone dip to the east and northeast

5. Typical log from the Ford Geraldine unit well no. 108

6. Map showing location of study area and outcrop exposure of Bell Canyon Formation

7. Sandstone-body architecture for turbidity-current model and saline-density-current model

8. Photograph of laminated siltstone, facies 3

9. Photograph of thin-bedded sandstones and siltstones, facies 4

10. Photograph of structureless sandstones, facies 5

11. Photograph showing deformed bedding contemporaneous with deposition, facies 5

12. Photograph of large-scale cross-lamination, facies 6

13. Photograph of climbing dunes, facies 6

14. Topographic map of Willow Mountain study area showing location of measured logs and cross sections

15. Cross section A-A' showing distribution of facies and traces of key surfaces within a single high-order cycle, Bell Canyon Formation

16. Cross section B-B' showing distribution of facies and traces of key surfaces within a single high-order cycle, Bell Canyon Formation

17. Cross section C-C' showing distribution of facies and traces of key surfaces within a single high-order cycle, Bell Canyon Formation

18. Photograph of channel-levee deposits and the same photograph with facies and surfaces labeled

19. Diagram illustrating depositional facies model for high-order cycle examined at Willow Mountain

20. Status of wells in the Ford Geraldine unit and distribution of core control

21. Laminated siltstone fining upward into organic-rich siltstone

22. Photograph of graded sandstone having floating clasts and overlying lutite

23. Photograph of sandstone having convoluted beds interpreted as loading and dewatering features at the base and massive sandstone above

24. Photograph of sandstone having flame structure, which is interpreted as a loading and dewatering feature

25. Photograph of climbing ripples in sandstone from well FGU-14, 2,728.2 to 2,729.1 ft

26. Photograph of cross-laminated sandstone from well FGU-130, 2,670.0 to 2,670.4 ft

27. Dip cross section D-D' down the length of the Ford Geraldine unit

28. Core description and porosity and permeability data from the Continental Oil Company G. E. Ramsey 18 No. 7 well

29. lsopach map of the upper Ford laminated siltstone, measured from the Ford condensed section to the top of the Ford

30. lsopach map of the Ramsey 1 sandstone, the main reservoir interval at Geraldine Ford field

31. lsopach map of the SHI laminated siltstone, which was deposited during a break in sandstone deposition

32. lsopach map of the Ramsey 2 sandstone

33. lsopach map of the lower Trap laminated siltstone, measured from the top of the Ramsey sandstone

34. Cross section E-E' through the north end of Ford Geraldine unit, where the SHI laminated siltstone separates the reservoir into Ramsey 1 and 2 sandstones

35. Cross section F-F' through the south part of Ford Geraldine unit, where only the Ramsey 1 sandstone is present

36. Cross section G-G' through the south part of Ford Geraldine unit, where only the Ramsey 1 sandstone is present

37. Distribution of porosity and permeability in channel, levee, and lobe facies

38. The main controls on porosity and permeability in the Ramsey sandstones are authigenic cements, particularly calcite, and, to a lesser extent, chlorite

39. Map of percentage of the Ramsey sandstone that is cemented by calcite

40. Vertical permeability profiles from core-analysis data for five wells in the Ford Geraldine unit

41. No significant difference exists in the porosity-versus-permeability relationship in channel, levee, and lobe facies

42. Capillary-pressure curves and calculated radii of pore throats for Ramsey sandstones

43. Flow chart of petrophysical analysis

44. Prewaterflood isosalinity map with formation water resistivities at 75°F for the Ford Geraldine unit

45. Cross plot of core porosity versus core permeability for the Ramsey sandstone in the Ford Geraldine unit, Reeves and Culberson Counties, Texas

46. Normalized relative permeability curves for the five curves measured in the FGU-156 well

47. Distribution of porosity in Ramsey sandstone from 4,900 core analyses

48. Map of average porosity for the Ramsey sandstone in the Ford Geraldine unit

49. Distribution of permeability in Ramsey sandstone from 4,900 core analyses

50. Map of geometric mean permeability for the Ramsey sandstone interval, calculated from porosity data from geophysical logs and the core-porosity-versus-core-permeability transform

51. Map of permeability x thickness for the Ramsey sandstone in the Ford Geraldine unit

52. Distribution of water saturation in Ramsey sandstone from 4,900 core analyses

53. Map of mobile oil saturation for the Ramsey sandstone in the Ford Geraldine unit

54. Map of net pay for the Ramsey sandstone in the Ford Geraldine unit

55. Outline of the area in which the 3-D seismic survey was acquired

56. Synthetic seismogram generated for the FGU-128 well to correlate the seismic reflection character with the formation tops interpreted from well logs

57. Representative seismic line showing the top of the Castile, Lamar, Ramsey, and Manzanita intervals

58. Residual map of the Lamar peak showing localized structural high and lows

59. Ramsey amplitude map on the Ramsey trough seismic marker

60. Coherence extraction on the top of the Lamar limestone, made by processing the seismic volume using the coherency-cube transform

61. Plots of total oil production in the Ford Geraldine unit and volumes of water and CO₂ injected

62. Map of primary oil recovery for the Ramsey sandstone in the Ford Geraldine unit, Reeves and Culberson Counties, Texas

63. Map of secondary oil production resulting from the waterflood conducted from 1969 through 1980

64. Map of tertiary oil production through 1995 resulting from the CO₂ flood that started in 1981

65. Map of total oil production from the Ford Geraldine unit through 1995

66. Map of the percentage of water produced during initial potential tests

67. Map of water cut at the end of primary production in 1969

68. Waterflooding of the Ford Geraldine unit, conducted in five stages, in the areas shown

69. Original oil in place in waterflood areas 1 through 5

70. Primary, secondary, primary + secondary, tertiary, and total recovery through December 1995 as a percentage of original oil in place in areas 1 through 5

71. Oil recovery as a fraction of remaining oil in place for stochastic and layered permeability cases

72. Surface oil rate in stock-tank barrels per day for stochastic and layered permeability cases

73. Surface water-oil ratio for stochastic and layered permeability cases

74. Surface gas-oil ratio for stochastic and layered permeability cases

Tables

1. Facies characteristics of Bell Canyon sandstones and siltstones

2. Characteristics of depositional elements in the Bell Canyon Formation 

3. Mean porosity and permeability of upper Bell Canyon sandstones and siltstones and range of values

4. Design parameters for 3-D seismic acquisition

5. Highest correlation coefficients calculated from the data set of seismic attributes cross plotted with various rock properties

6. Highest correlation coefficients calculated from the data set of petrophysical parameters cross plotted with total oil recovery from Ford Geraldine unit wells through 1995

7. Fluid characteristics of reservoir



Citation
Dutton, S. P., Barton, M. D., Asquith, G. B., Malik, M. A., Cole, A. G., Gogas, John, Guzman, J. I., and Clift, S. J., 1999, Geologic and Engineering Characterization of Turbidite Reservoirs, Ford Geraldine Unit, Bell Canyon Formation, West Texas: The University of Texas at Austin, Bureau of Economic Geology, Report of Investigations No. 255, 88 p.