3. DATA SOURCE.pdf
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Transcript of 3. DATA SOURCE.pdf
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Data source
Section 3
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Outline
1. Pressure data source
2. Fluid gradient
3. Vertical stress/overburden stress4. Minimum horizontal stress (fracture pressure)
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1. Pressure data source
Data source Hierarchy
Repeat formation tester (RFT, FMT, MDT)
Formation interval test (FIT)
Drill stem test (DST)Well or pressure kick
Connection gas
Measurement whilst drilling (MWD/LWD)
Mudweight
Drilling exponent
Swarbrick, 1999
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MDT tool
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RFT/MDT
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RFT data chart
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Analog recording
Pressure build-up: formation permeability/mobility
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Accuracy of MDT/RFT
Quartz gauge:
error about 15 psi (Ireland et al., 1992)
New generation of quartz gauge
(combinable quartz gauge/CQG)
error about 2.5 psi
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Remarks on pressure data
TVDSS
(ft)TOOL GAUGE
FP
(psi)
EMW
(gr/cm3)
MOB
(mD/cp)FA
FLUID
LOGMARKER REMARK DATE
7449.37 RFT QG 3292 1.01 HC G 1a-a GOOD 6/2/1991
7449.37 RFT QG 3293 1.01 61 N/A G 1a-a GOOD 6/2/1991
8003.04 RFT QG 3610 1.04 14 N/A G 1d GOOD 6/2/1991
8608.20 RFT QG 3906 1.04 4.3 N/A G 1g GOOD 6/2/19918646.74 RFT QG 3854 1.02 876 N/A G 1h GOOD 6/2/1991
8670.52 RFT QG 3853 1.02 273 N/A G 1h GOOD 6/2/1991
8682.00 RFT QG 3854 1.02 974 N/A G 1h GOOD 6/2/1991
8695.12 RFT QG 3855 1.02 938 N/A G 1h GOOD 6/2/1991
8708.24 RFT QG 3856 1.02 45 N/A G 1h GOOD 6/2/1991
9898.81 RFT QG 4430 1.03 N/A G 2g N.S 6/2/199110907.74 RFT QG 5291 1.12 N/A G 4a S.C 6/2/1991
10950.05 RFT QG 5384 1.13 1.4 N/A G 4b GOOD 6/2/1991
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Remarks
Good: reliable pressure data
NS: not stabilised (not enough time to
directly determine pressure value)
SC: supercharged unreliable pressure
data due to mud invasion
Tight: unreliable pressure data due to tightreservoir
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3000 4000 5000 6000 7000
7000
8000
9000
10000
11000
12000
13000
Pressure (psi)
Depth(ft)
Supercharged
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2. Fluid gradients
g
dz
dPw
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Specific
gravity
API gravity Normal
hydrostatic
grad. (psi/ft)
Total
Dissolved
solids (ppm)
1.14 (brines) -7.50 0.494 210,000
1.12 -5.20 0.485 175,800
1.10 -2.70 0.476 143,500
1.05 30 0.455 69,500
1.00
(fresh water)
100 0.433 zero
0.95 170 0.411
0.9 250 0.390
0.85 (light oil) 350 0.3680.8 450 0.346
0.7 600 0.303
0.4 (gas) 0.130
Simplified from Dahlberg, 1982
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Water grad. : salinity measurement
HC grad. : API measurement
Water & HC: could be inferred from
pressure
depth plot, if the pressuremeasurement close enough
Fluid gradients
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0 2000 4000 6000 8000 10000
0
2000
4000
6000
8000
10000
12000
14000
Example: Kutai BasinPressure (psi)
Depth
(ft)
0.433 psi/ft
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Some examples of hydrostatic gradient
Region Hydrostatic gradient
(psi/ft)Anadarko 0.433
California 0.439
Gulf of Mexico 0.465
Mackenzie Delta 0.442
Malaysia 0.422
North Sea 0.452
Rocky Mountains 0.436
Santa Barbara Channel 0.452
West Africa 0.442
West Texas 0.433
Kutai Basin 0.433
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HC gradientPressure (psi)
Depth(ft)
Water: 0.433 psi/ft
HC: 0.1 psi/ft
HC RFT point
Water RFT point
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HC gradientPressure (psi)
Depth(ft)
HC RFT point
Water RFT point
Variable HC-water contact?
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Indication of hydrodynamic trap:
will be discussed later
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3. Vertical stress/overburden stress
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Fluid
Overburden
()
Rock matrix
=p
(pore pressure)
+ (effective stress)
b
gzb g
dz
db
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Average density down to 3 4 km:
2.3 g/cm3
g
dz
db
pa/m23000smkg23000102300 22
dz
d
psi/ft1KPa/m23 dz
d
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1 psi/ft
Vertical stress/overburden stress
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Example: Shelf, Kutai Basin
1 psi/ft only at depth
Ramdhan & Goulty, 2010
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Example:
Baram Delta
Variation of
vertical stress
due to uplift and
undercompaction
Tingay et al., 2003
W ld id l
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World wide example
Mouchet and Mitchel l , 1989
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Vertical stress from wireline logs
The most reliable: density log
Sonic, resistivity, etc.
Density (g/cm3)
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Example of reasonably
good density log
- Oil-based mud
- Measurement every 0.5 ft- No density data in the
shallow section
Density (g/cm3)
Depth(ft)
Trend 1
Trend 2
Caving?
D it ( / 3) D th (ft)
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1.50
1.87
2.02
2.13
2.22
2.29
2.35
2.40
2.44
2.49
2.52
2.56
2.60
2.62
Density (g/cm3) Depth (ft)
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
12000
13000
14000
0
n
ib
zg1
Exercise
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1.50
1.87
2.02
Density (g/cm3) Depth (ft)
1000
2000
3000
0 1
2
3
@2000@3000
@1000 = 1
@2000 = 1 + 2
@3000 = 1 + 2 + 3
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1.50
1.87
2.02
Density (g/cm3) Depth (ft)
1000
2000
3000
0
Depth (ft) n = bgz (Pa) n (Pa) n (psi)
1000 1500 x 9.8 x 1000 x 0.3048
= 44805604480560
650
2000 1870 x 9.8 x 1000 x 0.3048= 5376672
9857232
1429
3000 2020 x 9.8 x 1000 x 0.3048
= 603382115891053
2304
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0 2000 4000 6000 8000 10000 12000 14000
0
2000
4000
6000
8000
10000
12000
14000
Pressure (psi)
Depth
(ft)
1 psi /ft
The realoverburden gradient
1 psi/ft is only
at depth
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0 2000 4000 6000 8000 10000 12000 14000
0
2000
4000
6000
8000
10000
12000
14000
Pressure (psi)
Depth(ft)
1 psi /ft
Shelf overburden
Deep water overburden
Mud line
Deep water overburden profile
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4. Minimum horizontal stress (fracture pressure)
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Leak-off test
White et al., 2002
E l K t i B i
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Example: Kutai Basin
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Example: world-wide
Breckels and Eekelen, 1982
Power law: bH
az
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Some notes on minimum horizontal stress
(fracture pressure)
The deeper, the greater the gradient
following power law
Couple pore pressure fracture pressure
Overpressure-induced
increase fracture pressure Production-induced
reduce fracture pressure
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Review
1. Pressure data source
Direct: RFT/MDT, FIT, DST
Indirect: drilling parameters
2. Hydrostatic fluid and hydrocarbon
gradients
Fluid density Pressure data
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Review
Vertical stress gradient: density
Minimum horizontal stress/fracturegradient: LOT
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Question?