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Exploitation and Optimization of Reservoir

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Presentation on theme: "Exploitation and Optimization of Reservoir"— Presentation transcript:

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 Procedure
1. 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

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