1. Exploitation and Optimization of Reservoir
Performance in Hunton Formation, OK
Review of Budget Period I
DE-FC26-00BC15125 By
Mohan Kelkar

2. Partners in Project The University of Tulsa The Department of Energy
Marjo Operating Company
The University of Houston
Jim Derby and Associates
Joe Podpechan and Jason Andrews

3. Outline Objectives of the project Progress so far Conclusions BP I
Future work

4. Objectives
To understand the primary production mechanism by which oil is being produced from the West Carney field
To develop procedures for extrapolating the production methods to other wells and other reservoirs exhibiting similar characteristics
To extend the life of the field beyond primary production

5. Tools Used Geological Description Log Analysis Flow Simulation
Rate-Time Analysis
Laboratory Data Collection and Analysis

6. Location of West Carney Hunton field

7. Lease Map of the West Carney Hunton field

8. Characteristic Behavior
Water oil ratio decreases over time
Gas oil ratio first increases and then decreases with time
Increase in GOR when the well is reopened after workover
Some wells exhibit pressure drawdown when the well is shut-in
Association between oil and water production

9. GOR after shut in

10. Presence of Fractures
Core photographs indicate the presence of fractures

11. Presence of Fractures
High permeability, in excess of 1000 mD has been observed at some locations
High water rates also indicate the presence of fractures
Communication between wells has been observed
Well test data also indicates fractures

12. Presence of Fractures

13. Relation Between Oil and Gas Production
Wells that produce oil also produce gas
Oil and gas exhibit the same production trend

14. Relation Between Oil and Gas Production
Plot of oil rate vs gas rate for all the wells
suggest the same behavior

15. Limited Aquifer
Reservoir pressure has been declining in the field

16. Limited Aquifer
Water rate is also declining in the field

17. Bulk of the Hydrocarbon Production is Through Water Zone
Some wells have shown good fluorescence but are bad producers
These wells also produce less water

18. Bulk of the Hydrocarbon Production is Through Water Zone

19. Core Descriptions and Analysis
Twenty seven wells have been cored, data from twenty two wells was available for this study
Cores have been analyzed at Stim Lab
Fourteen cores have been described in detail
Three lithologies; limestone, dolomite and partly dolomitized limestone have been identified
Fourteen facies types have been recognized
Four pore types; vug, coarse matrix, fine matrix and fracture have been recognized in each of the three litho types.
Results from Conodont studies have been used to demarcate the cochrane and clarita formations

20. Generalized lithofacies distribution

21. Location of the cored wells

26. Correlation of Core data to Log data
Comparison of core derived porosity to log derived porosity
Making of core-log plots
Reduction of pore types
Use the  vs Ln K relation to generate K values at un-cored wells

27. Core  Vs Log 

29. Log Evaluation Determination of Sw Determination of BVW
Sw = Water Saturation
 = {(D2+N2)/2}1/2
m = 1.77
a = 1
n = 2
Rw= 0.035
Determination of BVW
BVW = Bulk volume water

30. Log Evaluation (contd)
Determination of oil in place
BAF = barrels per acre foot
Sw = water Saturation
Ht = hunton thickness of each well
h = thickness of each data point
 = porosity

31. Buckles Plot Approach

33. Invaded zone
Oil zone

34. Electrofacies Analysis
Electrofacies is a term used to describe litho units that show similar response on electric logs
Principal component analysis
Cluster analysis
Discriminant analysis

35. Principal Component analysis
Reduction of data to lower dimensions
Minimal loss of information
First few principal components explain maximum variance

37. Cluster Analysis Method of clustering data into groups
Partitioning algorithms that use a pure mathematical criteria
Number of clusters to be provided can be determined from the clusplot

39. Discriminant Analysis
Used for extending the cluster analysis to the raw data
Creates a discriminant function based on groups
Applies this function to group the raw data

45. Correlation of static data to dynamic data
Production data for competitor wells was collected from public domain
Wells were declined at a rate of 50% per year and cumulative production for a six year time period was calculated
Pickett plots for each well were compared to the production data.

54. Recovery Factor calculations
Rfoil =
Boi = Initial oil volume factor
Np = Oil produced
N = oil in place
Rfgas =
Rsi = Initial solution gas oil ratio
Gp = Gas produced

59. Single Well Numerical Model
Production characteristics to be reproduced from numerical model
Initial decline in GOR
Association of oil production with that of water production
Decreasing water-oil ratio
Increase in GOR after the well was shut-in

60. Single Well Numerical Model
Gas
Oil
Water

61. Single Well Numerical Model

62. Results

63. Results

64. Results

65. Results

66. Results

67. Results

68. Rate-Time Analysis
Estimate permeability and skin factor for wells using available production data
Improve understanding of West Carney Field which exhibits complex production characteristics
Develop procedures for estimating in place reserves in the field.

69. Reservoir Model Description
Three layer-no cross flow
Analysis should give:
3 external radius values
3 permeability values
3 skin factor values

70. CR #2-15 Water: qDdL vs. QDdL

71. CR #2-15 Water: q vs. t

72. CR #2-15 Water Results

73. CR #2-15 Oil: qDdL vs. QDdL

74. CR #2-15 Oil: q vs. t

75. CR #2-15 Oil Results

76. CR #2-15 Gas: qDdG vs. QDdG

77. CR #2-15 Gas: q vs. t

78. CR #2-15 Gas Results

79. Summary of Field Cases

80. Results Generally, consistent with field observations
Wells acid fractured, so negative skin expected
Wells drain more than 160 acres
Oil and Gas layers have much lower permeability than the Water layer

81. Lab Work Methodology CT Scan
Wettability using standard Amott wettability test
Unsteady state relative permeabilities
Dean Stark analysis
Correlation between wettability and relative permeabilities
Wettability alteration tests

82. Experimental Procedure1. 2. 3 4 5 Pc
Water Saturation, Sw

83. Mary Marie#4968.6/4968.7 Porosity=9.7% Absolute Perm =1.32 md
Water index = 0.15
Oil index = 0.11
Amott Wettability index=0.04

84. Imbibition Relative Permeability

85. Mercury Capillary Pressure
1: Carter , 2: Wilkerson , 3: Mary Marie

86. Correlations As porosity and absolute permeability increase
rock becomes more oil-wet.

87. Correlations As rock becomes more oil-wet end point
relative permeability increases.

88. Conclusions
Reservoir is highly heterogeneous; karst and fractures affect well performance
Dual permeability system seems to exist
Fine matrix rock seems to be better connected to the high permeability component
Low recoveries from the coarse matrix and vuggy rock suggests that these are isolated pores
Decrease in reservoir pressure and water production confirms a limited aquifer

89. Conclusions (contd) Oil and gas co-exist in the field
Electrofacies analysis successfully differentiate between the oil zones and the invaded zones
Wells with high proportions of electrofacies # 4 & 5 are good producers
Wells calculating high oil in place from log data are not necessarily good producers

90. Conclusions (Contd.)
Study confirms that the field is highly heterogeneous and wells are in communication with each other through fractures
It is possible to determine drainage radius from material balance and use automatic type-curve matching to determine permeability and skin.
Skin factor results provide a useful tool to determine completion effectiveness

91. Conclusions (Contd.)
Hunton rocks are found to be neutral wet to oil-wet.
In rocks studied ,oil wettability increases as absolute permeability and porosity increase.
The end point water relative permeability increases as oil wettability of rocks increase.

92. Future Work
Improve reservoir and fluid description for history matching
Improve logging analysis
Include multi-phase flow in rate-time Analysis
Investigate tertiary recovery mechanisms to improve the recovery
Conduct technical workshops