SPE166420 Case History—Combining Extreme Overbalance and
Dynamic Underbalance Perforating Techniques in Ecuador
Halliburton
Authors: Patricia Poveda, Alvaro Izurieta, Petroamazonas, Julio Lozada, SPE, Federico Rios, SPE, and Martin Schoener Scott, SPE, Halliburton
Presenter:
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INTRODUCTION
• The results of combined extreme dynamic overbalance (propellant) and
dynamic underbalance (surge chambers) applied to two oil wells with
very low production potential (Block 15, Ecuador) are examined.
• This technique has a much better outcome than expected.
SUMMARY
• Wells with drilling problems and dry wells lead to the introduction of new
technology to increase productivity and maximize the return on
investment (ROI).
• Application of dynamic underbalance and propellant-induced dynamic
overbalance in several wells provide excellent results and indicate this
technique has great potential.
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FORMATION DAMAGE AND OIL PRODUCTION ESTIMATION • Damage by completions and perforating Karakas and Tariq
• Damage by partial penetration Papatzacos
• Damage by deviation Bensson
After early well evaluations, it is seen that development of completion fluids, and
using perforating techniques with anchored guns and dynamic and static
underbalance conditions the, S = 0 ± 0.25 compared to production estimates
obtained with S = 0.
S = 0 ± 0.25 Spseudo = ?
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DYNAMIC OVERBALANCE
• Overbalance (EOB) (propellants) improves productivity, creates microfractures.
• Dynamic underbalance cleans the perforation tunnel and reduces crushed zone.
Crushed zone Removed crushed
zone
OVERBALANCE (EOB) vs DYNAMIC UNDERBALANCE
Perforating tunnel
ΔPob > Pfrac > Pres ΔPub < Pres
ΔPob + ΔPob = Balance?
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1. Previous design 2. Correlation 3. Perforate and ignite propellant 4. Time delay 5. Opening of vacuum chambers 6. Pressure equalization 7. Retrieve gun assembly
OPERATING PROCEDURE
RIH FIRE
GUN
IGNITE
PROPELLANT
PROPELLANT
BURN END
OPEN SURGE
CHAMBER
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STRING CONFIGURATION
4 6
2
1
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• Perforating with dynamic overbalance + dynamic underbalance • Combination of two techniques in a single-trip event
COMBINING BOTH TECHNIQUES
1 2 3 4 5
1.- Hydrostatic pressure
2.- Shoot and propellant burning, EOB
3.- Time delay ±5.33 min
4.- Surge chamber opened, dynamic underbalance
5.- Pressure equalizing
Reservoir Pressure
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• CASE 1
Interval:
10974 to 10978 ft (4 ft)
10982 to 10985 ft (3 ft)
Charges: 4 5/8 in., MaxForce 390 DP
Date: November 2012
Design: PULSEFRAC (DOB/DUB)
Casing gun: single trip
Expected:
Qf = 200 STB/day
J = 0.16 STB/day/psia
• CASE 2
Interval:
10303 to 10308 ft (5 ft)
Charges 4 5/8 in., MaxForce 390 DP
Date: December 2012
Design: PULSEFRAC (DOB/DUB)
Casing gun: single trip
Expected:
Qf = 308 STB/day
J = 0.102 STB/day/psia
CASE HISTORIES
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CASE 1
Parámetro Valor Unidad
Porosidad 17 fracción
Permeabilidad 70 md
Presión Reservorio 3498 psi
Radio Zona dañada 10 ft
Permeabildad Zona dañana 25 md
Módulo de Young 2.40E+06 psi
Módulo de Poison 0.25 psi
Gradiente vertical 0.68 psi/ft
Máximo gradiente horizontal 0.63 psi/ft
Mínimo gradiente horizontal 0.58 psi/ft
Viscosidad 0.8 cp
Esfuerzo Efectivo 6060 psi
Esfuerzo Compresivo 9343 psi
• Low-potential sand stone • h = 7 ft, low k • Microfracture length, Lf = 2.77 ft
RESULTS:
Pwf = 1581 psi
Qf = 369 STB/day
J =0.19 STB/day/psi
EXPECTED:
Pwf = 1581 psi
Qf = 260 STB/day
J =0.16 STB/day/psi
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CASE 2 • Low-potential sand stone, in only two wells in this field • Thickness, h = 5 ft, low k • Microfracture length, Lf = 3.71 ft
Parámetro Valor Unidad
Porosidad 14 fracción
Permeabilidad 76 md
Presión Reservorio 3233 psi
Radio Zona dañada 8 ft
Permeabildad Zona dañana 25 md
Módulo de Young 2.70E+06 psi
Módulo de Poison 0.24 psi
Gradiente vertical 0.7 psi/ft
Máximo gradiente horizontal 0.68 psi/ft
Mínimo gradiente horizontal 0.58 psi/ft
Viscosidad 1.08 cp
Esfuerzo Efectivo 6256 psi
Esfuerzo Compresivo 9797 psi
EXPECTED:
Pwf = 200 psi
Qf = 308 STB/day
J =0.102 STB/day/psi
Well test data IPR curve
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
3200
0 100 200 300 400 500
Pro
ducin
g B
ottom
hole
Flo
win
g P
ressure
, psig
Total Liquid Flow Rate (stb/d)
RESULTS:
Inicial:
Pwf = 1270 psi
Qf = 482 STB/day
J =0.245 STB/day/psi
Actual:
Pwf = 691 psi
Qf = 484 STB/day
J =0.19 STB/day/psi
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• Conventional perforating with wireline and the combination of dynamic
overbalance and underbalance improves connectivity within the reservoir.
• The delay between dynamic events is crucial to the performance of
combining these techniques.
• It is recommended that high-speed pressure recorders be used with this
technique for the first wells to validated the models and results.
• Dynamic overbalance and underbalanced techniques are recommended for
reservoirs with poor quality rock properties and no water-oil contact.
• Using the above technique is also applicable in older wells (WO). A detailed
analysis of the well bore (quality of cement, rock properties) is
recommended.
CONCLUSIONS AND RECOMMENDATIONS
Thank you!
Questions?
Halliburton. SPE166420
Case History—Combining Extreme Overbalance and Dynamic Underbalance Perforating Techniques in Ecuador
