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Life of Field RS Problem
Reservoir Surveillance Fundamentals
Ref. P. 6–71
Depositional Environment (Model)
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
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Log Section, Depositional Environment (DE), and BottomHole Pressures
In the following stratigraphic cross section, the depositional environment is interpreted to be a fluvial sequence. Indications are that the reservoirs are compartmentalized.
Additional data: • Well #1 – dry hole• Well #2 – gas producer (1990 BHP 1594 psi [10,990 kPa])• Well #3 – gas producer (1988 BHP 2810 psi [19,374 kPa])• Well #4 – gas producer (1988 BHP 2856 psi [19,691 kPa])• Well #5 – dry hole
Case Study RS Through the Life of a Field
Depositional Model, Against Five Wells
0
500
1000
Spill Point
Crevasse
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
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Uncertainties in Reservoir Driving RS
Φ
Faults?
Properties of Gas - Bg
Volume in Place
Remaining Gas in Place
Are wells connected?
Are wells deviated?
What facilities are nearby?
Capacity
Type? Oil, gas
The RS budget?
k and Sw
Sorting and bedform
Depositional environment details
Volumetrics Mapped Dimensions – Static Model
43,560 ∗ ∗ ∗ ∗ 1
Original-Gas-in-Place (OGIP, scf) =
Where:
A = area (acres)
Hgross = gross thickness (ft)
Bgi = gas volume factor (rcf/scf)
Channel Crevasse
h 25 8
w 3,000 2,800
por 0.2 0.15
Sg 0.75 0.6
L 14,500 14,500
Bg 200 200
BCF 32.6 5.8
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
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0
850
1700
2550
3400
4250
0. 12.5 25. 37.5 50.
Gp (Bscf)
P/z(psi)[lPa]
Channel = 32.6 BCF
Crevasse= 5.8 BCF
P/z for Gas Pool
[29,303]
[23,442]
[17,582]
[11,721]
[5,861]
Let’s Look at a Nearby Area…
P. 9–36
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
© PetroSkills, LLC. All rights reserved._____________________________________________________________________________________________
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Seismic Section Over Zone of Interest
Background noise and the magnitude of the features
How to Separate the Two Similar Features, Both FluvialChannels that Are Only 4 Milli-seconds Apart ?
How and where to separate resolved from unresolved domains?
Much distance to separate two anticlines to make it clear that there are two?
Far apart must two faults be to recognize that there are two faults?
Resolution considerations are clearly important in all geologic reservoir surveillance, some of these are:
Other factors include:
“Resolution is the ability to separate two features that are very close together; the minimum separation of two bodies before their individual identities are lost” (Sheriff, 1991).
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
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Done at the time that Industry was trying to adopt VSPs, where source is placed near a well and geo-phones placed in well.
Walk Away VSP
VSP Surveys can also be done, during drilling and can also be integrated to give a much clearer view of the reservoir.
Integrated VSP Surveys
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
© PetroSkills, LLC. All rights reserved._____________________________________________________________________________________________
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VSP and 3D Seismic Line – Now Let’s Compare to Seismic
Magnified View of Seismic Cube Over Our Wells
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
© PetroSkills, LLC. All rights reserved._____________________________________________________________________________________________
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What Other Collaboration Data Might We Obtain? – PTA
Depositional Model of the King Field Upper Reservoir Figure 4 SPE 84380 Using Multiple Reservoir Measurements to Improve Subsurface Description in Deepwater Gulf of Mexico: King FieldSammy Haddad, SPE, Schlumberger Oilfield Services, Gerard Simms, SPE, BP, and Colin Clerk, BP
History Match of Pressure Build-up
Be
gin
bo
un
dary
eff
ect
s
1600[11032]
1400[9653]
1200[8274]
1000[6895]
800[5516]
0.001 0.01 0.1 1 10 100
Bot
tom
hole
pres
sure
(ps
i) [k
Pa
]
Actual buildup
Modeled reservoir dimensions
16x1 rectangle
Actual
Simulated
Test date: 4/23-26/93
Test interval: Middle Jasper Creek
Shut-in time (hr)
k = 28 mdh = 17 ft
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
© PetroSkills, LLC. All rights reserved._____________________________________________________________________________________________
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Ref. P. 6–72
Learnings from Gas Pool Exercise
Use all the available technology you can economically justify
Corroborate and confirm with other disciplines, notable G & G
Reservoir Surveillance Fundamentals ═════════════════════════════════════════════════════════════════════════
Life of Field RS Problem
© PetroSkills, LLC. All rights reserved._____________________________________________________________________________________________
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