Chato low gravity cryogenic liquid acquisition for space exploration 2014
SPE 106712
1. SPE 106712
Case Study from 12 Successful Years of High Temperature
Fracturing in Bach Ho Field Offshore Vietnam
S. Jain, A. Prestridge, P. Dellorusso, N. C. Nghi
Schlumberger
D.D. Lam, V.Q. Hung
Viestsovpetro
3. SPE 106712
IntroductionIntroduction
• Bach Ho field is located in the South China Sea, close to
Vung-Tau, Vietnam
• Field has 215 wells with an average seawater depth of 165 ft
• Production is from the Miocene, Oligocene and the Basement
formations
• Drilling practices and other damage mechanisms restrict
most wells from producing to their potential
4. SPE 106712
IntroductionIntroduction
• Propped fracturing is conducted in Oligocene whereas both
acidizing and fracturing have been tried in the Basement.
• High temperatures (>275oF), closure stress (>8,000 psi) and
operating from a vessel makes the execution of fracturing
treatments challenging.
5. SPE 106712
Reservoir DescriptionReservoir Description
• Average well depth - 12,500 ft
• Average porosity - 13 to 17%
• Permeability - 0.1 to 20 mD
• Water saturation - 10 to 15 %
• Presence of Migratory Clays
7. Equipment SetEquipment Set--upup
Rental for vessels
ranges from $10,000
to $30,000/day
Equipment tailored
to enable faster rig-
up/rig-down
Vessel put together
for fracturing o/p in
8 days and the
demobilization was
completed in only 2
days
Storage
tanks
Lab. &
Monitoring unit
Proppant
Silo’s
POD
Coflexip
hose
Pumps
8. SPE 106712
Design ConsiderationsDesign Considerations
• Fracturing Fluid - Zirconate C/S-Linked
Polymeric Fluid
• Rheology - 110 cP at 170 sec-1 and 300°F
• Proppant - High Strength Proppant
• Fluid loss - 0.003 to 0.007 ft/min1/2
• Polymer Clean-up - Combination of encapsulated
and live breaker
11. SPE 106712
Case Study (Well A)Case Study (Well A)
• Target zone - Oligocene
• Total Vertical Depth (TVD) - 12,100 ft
• Perforation interval - 160 ft
• Shot density - 6 spf
• Permeability - 6 mD
• Porosity - 14%.
12. SPE 106712
Well A - Production History
0
200
400
600
800
1000
1200
1400
1600
Nov-04 Feb-05 May-05 Sep-05 Dec-05 Mar-06 Jul-06
Time
OilProduction(BOPD)
1400 bopd
(naturally
producing)
130 bopd
(gas-lift)
Production History
20. SPE 106712
Well A - Production History
0
200
400
600
800
1000
1200
1400
1600
Nov-04 Feb-05 May-05 Sep-05 Dec-05 Mar-06 Jul-06 Oct-06 Jan-07
Time
OilProduction(BOPD)
Post Frac.
Production
460 bopd
Pre Frac.
Production
130 bopd
Production History
21. SPE 106712
Abnormal Treating Pressures
• Higher Surface pressure
at the start of the main
treatment
• Undesirable due to high
HHP and surface treating
pressure limitations
• Poroelasticity and stress
concentration expected as
possible reasons 7.0 47.0
0
2000.00
4000.00
6000.00
8000.00
10000.00
TreatingPressureBa
SlurryRate(JobData)
ProppantConc(JobD
TreatingPressure
Time(min)
Pressure(psi)
+
3500psi
22. SPE 106712
Abnormal Treating Pressures
• Increase in closure pressure as a
result of increasing reservoir
pressure
• Large relatively clean zones,
combined with the fact that the
treating pressures decreased
within few minutes of the start of
the treatment does not support
poroelasticity as a possible factor
• Alteration in magnitude and
orientation of the in-situ stress
field locally, can be about
twice the effective stress.
• Crosslinked gel filter cake seals
the fracture face in the near
well-bore region, hence
pressure must exceed the
stress concentration effect
before a fracture can be
initiated
ppVH αασ
υ
υ
σ +−
−
= )(
1
Poroelasticity Stress Concentration
24. SPE 106712
0
100
200
300
400
500
600
A1 A2 A3 A4 A5 A6 A7
Well Name
lb/ftofproppantpumped
0
10
20
30
40
50
60
RatioofPI
lbs of prop. pumped / Net Height
Ratio of PI increase (normalized)
Quantity of Proppant/ft vs. PI Increase
25. SPE 106712
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
B1 B2 B3 B4 B5 B6 B7 B8 B9 B10
Well Name
PI(bbl/day/psi)
Pre Treatment PI
Post Treatment PI
Acid & Propped Frac.
Acid Fracturing
Acidizing
Comparison of PI for treatments in Basement
26. SPE 106712
ConclusionsConclusions
• Fracturing successfully implemented in the White Tiger
field with over 60 treatments performed at a success
rate greater than 85%.
• Average increase in Productivity Index of 5 times
• Propped fracturing has been successfully implemented in
Oligocene whereas high leak-off in the basement limits
its application in the latter.
27. SPE 106712
ConclusionsConclusions
• Abnormally high surface pressures observed in the start
of the treatment can be attributed to stress
concentration effects
• Higher volume of proppant pumped / feet of net height
results in higher PI thus indicating that bigger jobs can
improve NPV
• Acidizing results in improved productivity in the
basement but successfully executing propped fracturing
jobs with reasonable proppant volumes will result in
improved Productivity Index.
29. SPE 106712
Case Study from 12 Successful Years of High Temperature
Fracturing in Bach Ho Field Offshore Vietnam
S. Jain, A. Prestridge, P. Dellorusso, N. C. Nghi
Schlumberger
D.D. Lam, V.Q. Hung
Viestsovpetro
