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IPM DPT

Schlumberger Private

Perforating

Objectives Perforating Session Objectives: • At the end of the session, you will be able to: Explain the purpose of perforating; Describe the different methods of perforating; Understand the key factors that affect gun selection; Explain the safety considerations of perforating; and Use SPAN* to perform perforating simulation.

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• • • • •

Outline Perforating • Purpose & history of perforating • Explosives and charges • Perforating techniques • Perforating damage • Perforating for productivity • Safety considerations • Introduction to SPAN*

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• Gun types & selection

Perforating Process Reservoir Description Completion Design Simulators Nodal, SPAN*.. Monobore Multiple..

Performance Data Base Field Specific Job Design

Execution (Optimize)

Perforating Parameters

Hardware

Treatment

Gun Deployment

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Seismic Logs...

Purpose of Perforating

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• Perforating connects the wellbore with the pay zone of the reservoir. • Provides the flow path for reservoir fluids to enter the wellbore. • Successful stimulation and sand control operations are strongly dependent on perforation parameters • A key factor in well productivity. • NOTE: Dangerous operation that requires careful planning and execution.

Perforating History

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• Early perforating methods used a gun that fired a steel bullet. • Research found that these ‘guns’ were ineffective and that most bullets never made it past the casing into the reservoir. • Engineers later developed explosive charges to blow small holes in the casing and connect the reservoir. • Modern day methods have evolved utilising military antiarmour weapon technology with ‘shaped’ charges.

Explosives & Charges • Components: Outer Case; Primer Explosive; Main Explosive; Liner

Effect of shaped charges and liner:

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• • • •

Shaped Charge Case

Primer Main Explosive

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Conical Liner

Shaped Charge Perforation • The outer case is a containment vessel designed to charge jet to formation. • The main explosive charge is normally chosen based on the desired temperature rating of the shaped charge. • The primer provides the link between the detonating cord and the main explosive.

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hold the detonation force long enough for the shaped-

Shaped Charge Detonation • Detonation Mechanics: Schlumberger Private

• 1. Detonation Cord - Primer Explosive - Main Explosive • 2. Liner collapses - perforating jet 4 µ sec

Shaped Charge Detonation (2) • Detonation Mechanics:

9.4 µ sec

16.6 µ sec

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• 3. Jet impacts casing surface (100 GPA ) • 4. Jet passes through casing wall, cement and formation

Classification of Perforating Gun Systems • Through-Tubing • Casing

• Larger guns with big charges • Usually shot overbalance

• High Shot Density • Larger gun with more shots per foot • Used for tubing conveyed applications

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• Small guns to get through the tubing string • Can be shot underbalance

Another Classification of Gun Systems •Capsule Charge

•Hollow Carrier • • • •

Scallop Guns (1 11/ 16 & 2 1/ 8-in.) HEGS (3 1/8 & 4-in.) Port Plug Guns (4-in.) HSD (1.56 to 7-in.)

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• Enerjet (1 11/16, 2 1/ 8 , 2 1/2 -in. ) • Pivot Gun (1 11/16 -in.)

Types of Perforating Guns • Hollow steel carrier gun

• Pivot gun • Tubing conveyed

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• Expandable strip gun

Hollow Steel Carrier Gun Schlumberger Private

Expendable Strip Gun

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Expendable Enerjet

Pivot Gun

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OD running in 1 11/16-in

OD deployed 3.79-in

Tubing Conveyed Perf Gun Schlumberger Private

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Perforating Gun Selection

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Perforating Gun Selection (3)

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• Clearance & Stand-off • Casing Strength • Effective Formation Strength • Wellbore Fluid • Temperature

Temperature Effects on Explosives

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Perforating Techniques • Through-Tubing Perforating

• Casing Gun/ High Shot Density Guns • • • •

Port Plug Guns, HEGS* and HSD guns Gun size limited by casing size Wireline conveyed in overbalance: larger interval (60 ft) Low Debris Guns

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• HyperDome*, Enerjet* or Pivot* - Carrier Guns • Completion tested, Underbalance, Rigless • Limited Interval - 30 ft

Perforating Techniques (2) • Wireline:

• Tubing Conveyed Perforation (TCP): • • • • •

Long and multizone intervals Through tubing and casing/ HSD advantages Underbalance Perforation Wide variety of firing systems Expendable guns can be drop allowing through tubing operations

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• Faster and Economic • Limited Intervals - Deviated Wells

Perforating TCP Assembly

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Perforating Techniques (3) • Guns Enerjet* Pivot* HSD* Big Shot

• Release Mechanisms • WAXR* • SXAR* • MAXR*

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• • • •

Perforated Casing

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Perforating Damage • At perforation impact: • Reduces to small fragments the adjacent rock. • Fractures sand grains. • Debonds clay particles.

• Generate additional effects : • Injection of explosive products • Injection of wellbore fluids.

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• Fails inter-grain cementation.

Perforating Damage (2) • The primary perforation damage observed in laboratory experiments results from the grain fragmentation creating permeability. • The extent of damage is a function of rock strength (porosity), lithology, pore fluid compressibility, clay content, grain size and charge characteristics.

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small particles that reduce pore throat size thus

Perforating Damage (3)

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Damaged Zone

Skin • Divided in • Mechanical Skin:

• Pseudo Skin: • • • •

Completion improper diameter Shot density Turbulence Perforation plugging

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• Drilling, Completion fluids • Perforation damage

Perforating Parameters

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• Geometry factors • Importance related to completion type and formation conditions • Shot density more important than shot penetration

Removal of Perforation Damage • Underbalance perforating • Perforation washing • Acidizing (remove damage) • Fracture (bypass damage)

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• Back surge of perforations

Well Completions Types: •Cased hole

•Wireline

•Gravel Pack Well Conditions:

•Underbalance •Overbalance

•Tubing •Coiled Tubing

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•Open Hole

Conveyance:

Cased Hole Completion •Usually, unconsolidated rock needs a casing and cement to keep well stability. Schlumberger Private

• Well is then perforated (casing-cementformation) in order to produce hydrocarbons

Open Hole Completion “Bare Foot” Completion limestone and dolomite, the hydrocarbon pay zone may not need casing and can be left to produce from the open hole

•Normally used in fractured reservoirs

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•In very consolidated rocks such as

Gravel Pack Completion Gravel Packed Liner •Used as a screen to keep unconsolidated

•Fluids can flow through the GRAVEL and SCREEN

•Most commonly used in unconsolidated sandstones

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formation out of the wellbore

Wellbore Conditions While Perforating

• Underbalanced • Extreme Overbalanced

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• Overbalanced

Overbalanced Perforating Completion fluid in wellbore Casing Schlumberger Private

Cement

Perforating gun Oil or gas reservoir

Phyd

Pres

Overbalanced perforating Phyd > Pres

Wireline Through-Tubing - Underbalanced •Wellbore pressure is less than Formation pressure

•Optimum perforation. Maximize productivity

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•Pressure equipment required

Underbalanced Perforating Completion fluid in wellbore Casing Schlumberger Private

Cement

Perforating gun Oil or gas reservoir

Phyd

Pres

Underbalanced perforating Phyd < Pres

Tubing Conveyed - Underbalanced

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Underbalance Perforating • If the stress caused by differential pressure and drag exceeds the rock failure, a progressive moving / erosion will occur in the permeability damaged region, cleaning perforation tunnel walls.

• The process may leave substantial sand debris in the perforation tunnel (secondary damage). This may be compromise production and gravel placement. • Post shot flow does not produce any substantial additional cleanup of primary damage. However the flow can help secondary damage.

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• The rock failure removes the permeability damaged zone. This is may eliminate skin.

Tubing Conveyed - Extreme Overbalance Nitrogen Pumping

Wellhead

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Tubing Packer

Production Zone Large Shapedcharge Gun Mud, Oil, and Salt Water Extreme Overbalance Completion Pw >> Pf

Extreme Overbalanced Perforating Pressurized gas Completion fluid in wellbore Casing Schlumberger Private

Cement

Perforating gun Oil or gas reservoir

Phyd

Pres

Extreme overbalanced perforating Phyd >>> Pres

Perforating Debris

• All perforating guns expel debris into the wellbore • Attempts have been made to contain the debris in the gun, collect it after perforating or minimize the quantity expelled • All perforating generates debris from casing, formation and guns

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• Perforating debris can create problems in highly deviated or horizontal wellbores and with completion hardware.

Sources of Perforating Debris • Case and liner debris from the shaped charge – Contribute >90% of total debris

• Small steel debris from the exit hole of the gun and the entrance hole of the casing • Formation and cement material This debris has not been a big issue until the advent of highly deviated and horizontal wellbores.

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• Charge jacket and tube debris from the charge retention system

Shaped Charge Case Debris Two strategies: Schlumberger Private

• Zinc case (CleanSHOT* or CleanPack*) – Reduces size of debris

• Steel case

– Pack charges in such a way that the case breaks into large pieces – Debris is too big to exit gun – Case debris stays in gun – Patented by Schlumberger

Bigshot guns use 2nd strategy

* Mark of Schlumberger

Perforating System Considerations? Deep Penetrators

Big-Hole Charges

High Shot Density Exotic Techniques

Slim Guns Orientation

Kill

Low Debris Charges Deployment

High Temperature Hard-Rock Charges

Phasing Carrier Guns High Pressure

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Underbalance

Capsule Guns

Perforating for Productivity • Formation Damage • Deep Penetrating Charges

• Anisotropy

• Perforation Skin • • • • •

Underbalance TCP Through-Tubing FIV, X-Tools CIRP, Stackable

• TCP, CT • FIV, X-Tools • CIRP, Stackable

• Deep/Hot Wells

• HPHT, HNS/HTX • Wireline • Through-Tubing

• Hard Formations

• Hard-Rock Charges

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• High Shot Density • Phasing

• Long Intervals

Perforating for Productivity (2) Perforation Parameter

Sand Control

Sand Prevention

Fracture Stimulation

Remedial Damage

Effective Shot Density

1

1

1

3

2

Perforation Diameter

4

1

3

2

4

Perforating Phasing

2*

2*

1

1

3*

Perforation Length

1

4

4

4

1

* Once the phasing is greater than 0° then phasing importance drops to a 4.

1= HIGHEST PRIORITY, 4= LOWEST PRIORITY

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Natural

Perforating for Sand Control • Gravel Placement & Skin Reduction Area-Open-to-Flow (AOF) Shot Density and Big-Hole Charges Phasing Reduction of Perforation Skin (Underbalance/Clean-up)

• Efficiency • PERFPAC • IRDV, SXAR, HSD Guns, Quantum Packer

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• • • •

Perforating for Sand Prevention • Retain Structural Integrity Deep Penetrating Charges High Shot Density Optimum Phasing (Maximize Perf-to-Perf Spacing) Limit Drawdown Oriented perforating

• Custom Gun Designs • 7-in. 27 spf HSD Gun • 3 3/8-in. 4 spf 99°

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• • • • •

Perforating for Fracturing • Pressure Drop

• Tortuosity & Leakoff • • • •

Phasing (180°, 60° , 120°) Orientation Micro Annulus or Multiple Fractures Deviation

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• Perforation Hole Size • Interval Length • Number of Shots

Perforating Deviated / Horizontal Wells • Debris

• CleanSHOT*, CleanPACK* Charges • Bigshot 21* • Gun Orientation • Special Guns (Top-side Shooting)

• Efficiency

• Coiled Tubing Perforating • FIV*, LTIV*

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• Skin

Perforating Operations • Safety Considerations • Explosives Handling • Safety First!

• Perforating Depth Control (PDC) • Well Control • Pressure control lubricator, ratigan bop, surface equipment

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• Standard Operating Procedures

Standard Operating Procedures Why Care About SOPs? Schlumberger Private

If precautions are not taken, the danger of surface detonation may occur!

SOP? Who Cares?

.....and you should too

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I Do !

Arrival At The Wellsite 1. Consult with Client

2. Check For Hazards • inspect site • check for transmission towers, etc.

3. Hold SPOT Safety Meeting • include client and all other effected personnel

4. Designate No Smoking Area

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• establish presence • verify job • confirm procedures

RF Concerns - Put out signs. - Deactivate all radio transmitters within 1000 ft (300 m). Schlumberger Private

WARNING Do Not Proceed if: you are within 5 miles, 8 km of a large transmitter (radio or TV) or within 200’ of High Voltage lines (>10Kv) or if wellsite transmitters cannot be deactivated.

Arming or disarming a gun must not be attempted during a thunder storm. (dust storms, sand storms, helicopters/boats approaching)

Return To Surface Procedure WARNING Do not retrieve the gun above 200 ft (70 m) downhole during storms or their imminent arrival.

Relieve any trapped pressure immediately upon removal from well.

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If the gun(s) did not fire, disarm the lowermost gun(s) first BEFORE disconnecting the head.

After The Job Police the site for any remnants and pack them in

sive o l p Ex nts a n Rem

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an Explosives Remnants box for return to the district

Perforating DEPTH Control This section covers: • Depth Positioning Devices • Perforation Depth Control • State the most likely reason for off-depth perforating and how to prevent it. • List the possible results when perforating off depth.

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Training Objectives for this section are:

1. Depth Positioning Devices • GR

• CCL • Allows correlation with CH logs (eg. CBL )

• Based on formation GR (to match peaks / shape)

• Based on Casing collar detection (or other completion markers)

• Gamma ray may change from OH reference (scale, etc) • Tools: PGGT-C or D, GPT (powered tool)

• It could be affected by noise in the casing (eg. corrosion, old perfs.) • Tools: CAL-B, CCL-L/N, CCL-AG

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• Allows correlation with any OH or CH log

2. Perforation Depth Control (PDC) PDC - Outline a. Job Preparation

c. Proper Tie-in d. Perforating & Pulling out of hole e. Off Depth Perforation problems

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b. Running in hole

Results of Off Depth Perforating (ODP) • Safety • Costs: Direct / Indirect • Damage to Reputation

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• Loss of Revenue : Direct / Indirect

Depth Positioning CCL Zone 3 2007

3 ft.

2010 Zone 2 2013

Zone 3

15 ft.

2020 CCL Depth For Shooting

27 ft. 2028 Zone 2

Zone 2 6 ft.

2034

2044 Zone 1 2052

Zone 1 8 ft.

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Zone 1 2017

Zone 3 10 ft.

Matching Reference & Correlation Log Correlation Log

Reference Log

C = Depth offset

C

GR

Nuclear Measure Point

CBL

Move collars up on the correlation log

GR

OH

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CCL

Correlation Log is “C” too Deep

CCL

Well Control Considerations • Safety • Lubricator • Ratigan BOPs • Pressure testing equipment • Procedures in event of well control incident

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• Fluid overbalance (> 200 psi)?

SPAN* - Perforating Analysis Software • SPAN*, Schlumberger’s Perforation Analysis Program.

• Estimates the combined influence of perforations, damage skin, partial penetration, and well deviation on the productivity of the well under natural depletion. • Estimates optimum underbalance perforating pressure based on theoretical / empirical solutions.

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• Predicts the size of the entrance hole and the penetration length of the shaped charge jet into the formation,