romania upstream conference - bucharest

Date: 24th March 2011

Alun Whittaker

Romania Upstream Conference - Bucharest24th March 2011

Selective Stimulation results in well productivity increase of 50%

© 2006 Weatherford. All rights reserved. 1

1. Stimulation Technique Discussion

2. System Components

3. Jet Frac Animation

4. Ekofisk Case Histories

5. Inflatable Jet Pack Straddle System

6. Future Developments

7. Questions

Presentation Outline

Presenter

Presentation Notes

General Outline Format of Presentation


Traditional Stimulation Techniques

• Bullheading acid down the production tubing or using diverter balls to direct the acid to the correct part of the formation.

– Sections of the formation in most need of stimulation does not receive treatment.

– Stimulation fluid travels through the path of least resistance (high permeability – low pressure)

– Difficult to treat reservoirs with different zone pressures


Challenges with Bull-heading

• HCl has a spontaneous reaction rate which is believed to cause cavities behind the liner

• Cavities are being linked to liner deformation due to point loading = reduces well accessibility

• Too much acid will eventually damage the well stability and integrity

• Ineffective stimulation of all zones in a well due to pressure and perm. variations along wellbore

• Re-stimulations mostly treats the best zones that are not in need of it


Challenges with Bull-heading

• Fluid tends to take the path of least resistance.

• Uniform distribution or proper diversion is a major factor in the success or failure of a treatment.


Benefits of Zonal Isolation

• Controlled placement of acid where required

• Effective stimulation of new zones in a well

• The identified zones in a well in need of a re-stimulation can be targeted specifically

• Treatment designs / mixes can be further optimized for selective stimulation

• Downhole pressure and temperature acquisition at the zone for reservoir modelling



• Ensuring uniform distribution of the stimulation fluid across the treatment interval. Essential characteristics include:

– Uniform treatment across varying permeability / pressured zones

– Non-damaging to formation (temporary plugging)

– Rapid and complete clean-up

– Compatible with treatment fluids and techniques

• General techniques include:

– Mechanical diversion

– Chemical diversion

– Foam diversion

Jet Frac™ Tool



Layer 1

Layer 2

Layer 3

k1 = 50 mds1 = 10k2 = 300 mds2 = 5k3 = 200 mds3 = 2

Damaged Zone

B

Layer 1

Layer 2

Layer 3

8%

33%

59%

Injected Fluid


System Components

Straddle Packers

• Designed for coiled tubing conveyed selective treatments

• No pipe movement required for setting

• No slips

• Multi set capabilities

• Sets at low flow rate <1bpm

• Rated to 7500 psi differential


System Components

Set Down Unloader

• Equalizes pressure between packers for easy release

• Pressure and Volume Balanced to open in blank pipe testing even with Back Pressure Valves in BHA


System Components

Acid Frac Valve

• Designed for multiple opening and closing cycles

• Large flow area

• Designed for flow rates up to 20 bpm

• Debris can not enter the hydraulic area


System Components

Memory Gauges

• Installed above, below and in between straddle packers

• Either Quartz or Piezo available

• Records treating pressure & temperature at the zone

• Provides diagnostics on system


Straddle Operation Animation


Ekofisk Field Information -

• Area 9 x 4,5 kilometers • Lithology: Naturally Fractured Chalk• Vertical Thickness 300 meters• Datum depth 10,500 ft TVD• Producing From Two Horizons• Waterflood and Subsidence drive mechanisms• High Porosity Matrix Rock (30-50%)• Low Productivity Matrix Rock (0.1 – 1 mD)• Effective permeability increases 10X w/ fractures• Perforated in 1-10 ft clusters w/ ~200 ft spacing• Perforation clusters have ~8 holes & sizes ~0.3”

Case History


• Stimulation vessel on location for pumping the treatment design through coil

• Designed tapered 2 7/8” Coiled Tubing to withhold high treating pressures and rates

• Depth correlation run on coil using a pulsation tool / CCL

• Zonal Isolation tool consisting of two packer elements, a spring-loaded valve to increase pump-thru area, memory P&T gauges below and between packers

Operation Overview


Case History - Equipment Rig Up


20 Tons2500 ft

Pipe Deck

CT Reel

CT Split Reel

Foundation

CT Reel

CT Split Reel

Foundation

CT Connection Jig4.5 Tons

Pipe Deck

32,5 Tons11500 ft

CT rig-up Operation


Equipment Preparation


Ekofisk Case Histories

• Case History 1

– Ekofisk Field

– 6 5/8” Liner set at 90 Deviation

– Setting Depth –4,809m – 3,810m

– 15 sets in Single Run

– > 8000 Bbl fluid pumped in total @ 17.1 BPM (2,930 Bbl of 28% Hcl)

– 3000 BPD greater than anticipated production rate from flank of the field.


Recent Operations

North Sea – Danish Sector – March 2008

• Major Operator

• First well – 6 sets – 1 ¾” OD Coiled Tubing

• Second well – 25 sets – 1 ¾” OD Coiled tubing

• Awaiting production results


Inflatable Jet Pack Straddle System

Offshore California

Selective Straddle Acidizing• A major operator’s well offshore California

required acid stimulation to increase production.

• A 2 ½” IJSP system was run and set six times inside the 5”. liner’s perforated interval between 2,749m - 2,785 m.

• 15% HCl was pumped at rates ranging from 1 to 1.5 Bbl/min at a maximum pressure of 4,000 PSI at each of the setting intervals.


IJPS Animation


Thank You & Questions

Thanks

• Romania Upstream

•Conoco Phillips Norway

• Audience

romania upstream conference - bucharest

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