Transcript Wertz Field: Core and Fluid Analysis

Wertz Field:
Core and Fluid Analysis
GROUP 8:
MOHAMMAD S.M.S.H. ALAJEEL
SAMUEL ANTRIM
SAMUEL DIELWART
GUIHE LI
THADDIUS ZEMPEL
Objectives
 Core and fluid analysis of the Tensleep formation in
the Wertz field
 Analyze WAG flood fluid interactions
 Determine increase in oil production due to WAG
flood
Ethics in the Workplace
 Asset Protection
 Productivity and Teamwork
 Public Image
 Decision-Making
What is the Code of Conduct?
 Basic rules, standards and behaviors necessary to
achieve those objectives.
 It provides requirements and guidance, expressed
clearly as is possible
 Is a common reference point for anyone who is
unclear about what is expected of them in a specific
situation
Why does a company need a Code of Conduct?
 Leading companies set the standards of performance
and behavior that others aspire to.
 Honesty, integrity and respect for people
How can the Code help you?
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 It provides requirements and guidance about how
you should relate to colleagues, customers,
shareholders, communities and governments.
 It can help you resolve difficult questions about
business conduct, and it explains how to get
confidential advice.
Code of Ethics for this Project
Canons
 II “Perform services only in areas of their
competence”
 IV “Act for each employer or client as faithful agents
or trustees”
Professional Obligations
 “Engineers shall avoid the use of statements
containing a material misrepresentation of fact or
omitting a material fact”
Ethical Issues
 Relationships with Clients.
 Conflict of Interest.
 Treatment of Confidential proprietary information.
 Outside Employment (Activates).
Coring Economics
 Wertz Field zone of interest

Approximately 470 ft
 Conventional coring



Conventional coring techniques with roller cone bits
$424/ft
Approximate cost: $199,000
 Diamond coring



Conventional coring techniques with polycrystalline diamond
compact (PDC) bits
$244/ft
Approximate cost: $115,000
Core Information
 Core used in analysis
 Operator: Amoco Production Company

Date: December 6, 1985

Well name: Wertz 133

Depth interval: 6660’-7041’
Wertz Field Tensleep Formation
Reservoir & Fluid Characteristics
Average Depth
Average Gross Thickness
Net Thickness
Gas-Oil Ratio @ Pb
Reservoir Temperature
Specific Gravity
API Gravity
6200 ft (1900m)
471 ft (144m)
263 ft (72m)
210 scf/stb
165oF (74oC)
0.85 g/cm3
35o
Permeability Vs. Porosity
1000.00
Horizontal Permeability
Vertical Permeability
Permeability (md)
100.00
10.00
1.00
0.10
0.01
0.00
2.00
4.00
6.00
8.00
10.00
Porosity (%)
12.00
14.00
16.00
18.00
10
1
4
7
10
13
16
19
22
25
28
31
34
37
40
43
46
49
52
55
58
61
64
67
70
73
76
79
82
85
88
91
94
97
100
103
106
Water Saturation (%)
Pre-WAG Flood Water Saturation
70
max=62
60
50
40
30
avg=30.15
20
min=10.2
0
Pre-WAG Gas Composition
Component
Per Cent by Volume
Oxygen
0
Nitrogen
4.09
Carbon dioxide
52.00
Hydrogen Sulphide
1.11
Methane
26.80
Ethane
6.35
Propane
5.35
i-Butane
0.79
n-Butane
2.05
i-Pentane
0.49
n-Pentane
0.54
Hexane plus
0.43
Bubble Point Pressure
𝑅𝑠𝑏
 𝑃𝑏 =
𝐶1 𝑒
𝐶3 𝐴𝑃𝐼⁰
𝑇+460
1
𝐶2
 Where:
 C1=0.0178
 C2=1.187
 C3=23.9310

For oils where the API gravity is greater than 30⁰
 Pb=870.9 psia
Oil Compressibility
 Above Pb: 𝐶𝑜 =
1 𝜕𝐵𝑜
−
𝐵𝑜 𝜕𝑝 𝑇
 Bellow Pb: 𝐶𝑜 =
1 𝜕𝐵𝑜
−
𝐵𝑜 𝜕𝑝 𝑇
+
𝐵𝑔 𝜕𝑅𝑠𝑐
𝐵𝑜 𝜕𝑝 𝑇
0.0018
0.0016
0.0014
Co (pis-1)
0.0012
0.001
0.0008
0.0006
0.0004
0.0002
0
0
200
400
600
800
1000
Pressure (psia)
1200
1400
1600
1800
2000
Solution Gas Oil Ratio
 Above Pb: 𝑅𝑠 =

1.204
𝑝
γg
18 10 𝑦𝑔
Where: 𝑦𝑔 = 0.00091𝑇 − 0.0125 𝐴𝑃𝐼0
 Bellow Pb: 𝑅𝑠 = 𝑝𝐶2 𝐶1 γ𝑔 𝑒
𝐶3 𝐴𝑃𝐼⁰
𝑇𝑅𝑒𝑠+460
250
 Where:


C1=0.0178
C2=1.187
C3=23.9310
For oils where the API
gravity is greater than 30⁰

200
Rs (scf/STB)

150
100
50
0
0
500
1000
Pressure (psia)
1500
2000
Formation Volume Factors
 Oil Formation Volume Factors
1.1756
 Bellow Pb: 𝐵𝑜 = 0.972 + 0.000147𝐹


Where: 𝐹 = 𝑅𝑠𝑐
γ𝑔 0.5
γ𝑜
Above Pb: 𝐵𝑜 = 1 +
+ 1.275𝑇𝑅
γ𝑔 0.25
0.0005𝑅𝑠𝑏
γ𝑜
+
0.0004 𝑇𝑅−60
γ𝑜 γ𝑔
Bg = 0.0282793
Bg (RCF/SCF)

𝑧𝑇
𝑃
0.2
1.16
0.16
1.14
1.12
0.12
1.1
0.08
Bg
Bo
0.04
1.08
1.06
0
0
500
1000
Pressure (pisa)
1500
1.04
2000
Bo (RB/STB)
 Gas Formation Volume Factor
Fluid Viscosities
 Dead Oil Viscosity
2.6
2.4
 μ𝑜𝑑 = 10 − 1

Where: 𝑥 = 𝑇 −1.163 𝑒
6.9824−0.04658 𝐴𝑃𝐼⁰


1.6
1
0
𝑝 𝑚
μ𝑜𝑑
𝑝𝑏
Where: 𝑚 = 2.6𝑝1.187 𝑒
1.8
1.2
Where: 𝑎 = 10.715 𝑅𝑠 + 100
Above Pb: μ𝑜 =
2
1.4
 Live Oil Viscosities
𝑏
 Bellow Pb: μ𝑜 = 𝑎μ𝑜𝑑

Viscosity (cP)
2.2
𝑥
−0.515
500
𝑏 = 5.44 𝑅𝑠 + 150
−11.513−8.98 𝑝 10−5
1000
1500
Pressure (psia)
−0.388
2000
Flood Fluid Analysis
DEFINING THE WERTZ FLOOD
•
•
•
1941: Single injection well drilled
primarily to recycle hydrocarbon
gasses
1954: Peripheral water flood implemented
early in the life of the reservoir
1986: Water alternating gas (WAG) CO2
flood implemented
Mobility
𝑘𝑟𝑤
𝑀=
μ𝑤
 Function of Kr and μ




𝐾𝑟 = 𝑓 𝑆𝑤
𝑆𝑤 = 𝑓 𝐵 𝑜
𝐵𝑜 = 𝑓 𝑦𝐶𝑂2
𝑦𝐶𝑂2 = 𝑓 𝑥

Where: x is the distance from the CO2 injection site.
 Simplifications

𝑦𝐶𝑂2 = Constant


Therefore: 𝐵o = Constant for each scenario
𝑆w = Variable

Therefore: varying 𝐾𝑟
μ𝑜
𝑘𝑟𝑜
Relative Permeability Comparisons

𝑘𝑟𝑤 =
𝐾𝑟𝑤 0 𝑆𝑤 𝐿𝑤
𝑆𝑤 𝐿𝑤 +𝐸𝑤 1−𝑆𝑤 𝑇𝑤
1−𝑆𝑤 𝐿𝑜

𝑘𝑟𝑜 =

Corey Parameters: 𝐿𝑤 , 𝐿𝑜 , 𝑇𝑤 and 𝑇𝑜 .
1−𝑆𝑤 𝐿𝑜 +𝐸𝑜 𝑆𝑤 𝑇𝑜
Swelling Effects on Mobility Ratio
 Swelling effects due to increased concentration of dissolved gas
 𝑆𝑤𝑊𝐴𝐺 =

𝑆𝑊𝑖
𝑆𝑊𝑖 + 𝐵𝑜 1−𝑆𝑊𝑖
Where:

𝑆𝑊𝑖 = 𝑃𝑟𝑒 − 𝐹𝑙𝑜𝑜𝑑 𝑊𝑎𝑡𝑒𝑟 𝑆𝑎𝑡𝑢𝑟𝑎𝑡𝑖𝑜𝑛

𝐵𝑜 = 𝑃𝑜𝑠𝑡 − 𝐹𝑙𝑜𝑜𝑑 𝐹𝑜𝑟𝑚𝑎𝑡𝑖𝑜𝑛 𝑉𝑜𝑙𝑢𝑚𝑒 𝐹𝑎𝑐𝑡𝑜𝑟
Viscosity Differences in WAG Flood
 Modified Beggs and Robinson Empirical Relation Equation
 𝑙𝑜𝑔10 𝑙𝑜𝑔10 μ𝑂 + 1 ≅ 𝐴1 + 𝐴2 𝑇𝑘 +𝐴3 γ𝑂 +𝐴4
 WAG flood reduced fluid viscosity by 25%
𝑃𝐶𝑂2
𝑇𝑘
+𝐴5
𝑇𝑃𝑏
γ𝑂
+𝐴6 𝐴𝑃𝐼⁰
Relative Permeability
Buckley Leverett Evaluation
 CO2 effects on the flood quantified macro scale analysis
 Tensleep formation in the Wertz field
 Fractional flow curve was constructed for comparison of floods
 Velocity and displacement calculated for Δtime of expected WAG effects
1
𝑓𝑤 = 1+μ𝑤 𝑘𝑜 ,
μ𝑜 𝑘𝑤
𝜕𝑥
𝜕𝑡 𝑆𝑤
=
𝑞𝑡 𝜕𝑓𝑤
,
𝐴Φ 𝜕𝑆𝑤 𝑡
𝑥=
𝑄𝑖 𝑑𝑓𝑤
𝐴Φ 𝑑𝑆𝑤
Fractional Flow Curves
Frontal Velocity and Flood Displacement
Dependent on Structure Characteristics






𝜕𝑥
𝜕𝑡
=
𝑆𝑤
Porosity
Formation Height
Distance between Injectors to Producers
Relative Permeability
Fractional Flow
Initial Water Saturation
𝑞𝑡 𝜕𝑓𝑤
𝐴Φ 𝜕𝑆𝑤
𝑥=
𝑡
𝑄𝑖 𝑑𝑓𝑤
𝐴Φ 𝑑𝑆𝑤
Reservoir Properties

Cores in Wertz field indicated segmentation/compartmentalization of the field

Led to 5-spot pattern flood

Therefore frontal displacement is a function of radial displacement

AreaΦ=2πx[Φh] where x is the distance from the injector to the fluid front and the Φh
operator is a value quantified by the Petra software for porosity-ft

The slope of the anticline was ignored because the gravitational effects facilitated flow
just as much as they hindered it

Reservoir properties are important to realize so the calculations can be accurately applied
Tensleep Floodplain
Log Correlation for ΦH operator
Tensleep Formation Distribution
Frontal Velocity
Frontal Flood Locations
Fractional Flow/Production Change
 There was an expected change in the oil flow rate with the introduction of the
CO2 into the oil which causes swelling and a drop in viscosity of the oil.
 This change in flow rate can be calculated by calculating the fractional flow of
water in the field before and after CO2 injection.
 These findings can be compared to the fractional flow curves to help determine
the expected change in oil production after the introduction of CO2 into the
reservoir fluid.
Calculations
 First we used the production graph of our wells to determine the water and
oil production before the WAG flood was implemented.


qw = 3.00 x 106 bbl/month
qo = 1.00 x 105 bbl/month
 Using these values we can then determine the fractional flow of the water
Before the WAG flood.
𝑞𝑤
3.00𝑥106
𝑓𝑤 =
=
𝑞𝑤 + 𝑞𝑜 3.00𝑥106 + 1.00𝑥105
𝒇𝒘 = 𝟎. 𝟗𝟔𝟕
 From this we can then find our initial water saturation from the fractional
flow curve.
𝒇𝒘 ⇒ 𝑺𝒘𝒊 = 𝟎. 𝟕𝟒
Production History
Swi
𝑆𝑤𝑊𝐴𝐺
 Using the initial water saturation we can then
calculate the water saturation at the start of the WAG
flood.
𝑆𝑤𝑊𝐴𝐺
𝑆𝑤𝑖
0.74
=
=
𝑆𝑤𝑖 + (1.15 1 − 𝑆𝑤𝑖 ) 0.74 + (1.15 1 − 0.74 )
𝑺𝒘𝑾𝑨𝑮 = 𝟎. 𝟕𝟏𝟐
𝑆𝑤𝑊𝐴𝐺
𝑓𝑤𝑊𝐴𝐺
 Using the fractional flow curve we can determine the
new fractional flow of the water after the flood was
implemented.
𝒇𝒘𝑾𝑨𝑮 = 𝟎. 𝟗𝟏
𝑓𝑤𝑊𝐴𝐺
Production After Flood
 Using 𝑓𝑤𝑊𝐴𝐺 value we can then determine the oil
production after the flood.
𝑓𝑤𝑊𝐴𝐺
𝑞𝑤
=
; 𝑤ℎ𝑒𝑟𝑒 𝑥 = 𝑞𝑜
𝑞𝑤 + 𝑥
3.00𝑥106
0.91 =
3.00𝑥106 + 𝑥
𝒒𝒐 = 𝟐. 𝟗𝟕𝒙𝟏𝟎𝟓 𝒃𝒃𝒍/𝒎𝒐𝒏𝒕𝒉
Change in Production
Future Recommendations
 Calculate the NPV of incremental WAG production.
 Continue to search for Wertz Tensleep relative
permeability and capillary pressure data to increase
the accuracy of the model.
References
 Holbert, D.R. Short Flow Period Pressure Buildup Test in a





Geologically Complex Area. SPE 5841. September, 1975, 1-11.
Kleinstelber, Stanley W. The Wertz Tensleep CO2 Flood: Design and
Initial Performance. Journal of Petroleum Technology. May 1990, 630636.
Kulkarni, Madhav M. et al. CO2 IOR Evaluation for the U.S. Rockey
Mountain Assests, Wyoming. SPE 113297, Tulsa, Oklahoma (2008) 113.
Swedenborg, E.A. Production of Oil Under Unitization in Wertz Dome
Field, Wyoming. Petroleum Transaction, AIME. June, 1949, 163-170,
258
Towler, Brian F.: Fundamentals Principles of Reservoir Engineering,
Society of Petroleum Engineers, Richardson (2002) 1-32.
Christensen, C. J. (1948, December 1). Diamond Coring in the Rangely
Field, Colorado. Society of Petroleum Engineers.
Questions?