Stopping OilfieldLightning Damage

You can not stop lightning!

True. But you can stop the damage it does!

An Engineering Approach

Oil Production Priorities

• Tank Batteries, does NFPA 780 really apply?

• Disposal pump motors and controls• Electric Submersible Pumps, ESP,

does API RP11S really apply?• ESP Variable Frequency Drives• Pumping unit motors and controls

Tank Battery Protection

• Strike Collection – with Franklin rods (Also called lightning rods, air terminals, etc.), catenary wires, early streamer emitters

• National Fire Protection Association (NFPA) and Lightning Protection Institute

• Strike Avoidance – Charge Transfer Systems

Electrical Equipment Protection

• 4-wire Transient Voltage Surge Suppressors (TVSS)

• Wellhead Grounding• Junction box TVSS mounting• Ungrounded transformer windings• Separate Ground Wires• Power distribution with an overhead

neutral, OHN, or shield wire

Tank Battery Protection

CL VSD

125 HP SWD Motor

Oil Storage300 Barrel12' dia, 15'-5" highSteel Each

catw

alk

Knockouts, steel10' dia x 20' long &10' dia x 15' long

Disposal Well150' East

Nort

h

500 HP SWD Motor

catwalk

Rolling Sphere Calculation

74 foot diameter

Scale 1" = 20'

Each, 1000 Barrels15'-5" dia, 30' highFiber glass, gun barrel, water sep.

Vertical Gas Separator3' dia x 12' high

Problems

• Presence of explosive gases• Fluids that develop an electrical charge• Attracting lightning and getting it safely

into the ground without igniting gases• Does NFPA 780 really apply?

Solution

• Prevent lightning from striking tank batteries

• Charge Transfer Systems - -Explanation Demonstration

• Details !! The devil is in the…………….. MIL TFP 41

Leader Delayed by Space Charge

Competing Leaders Continue toward

Earth

+

+

++

+

+

+++ ++

+

++

++

++ +

++ + + + +

++

++

++

__ ______ _ _

_ _

Winning the Competition

__ ______ _ _

_ _

+

+

++

+

+++

++

+

+

++

+ +

+

+

+

+

GroundingMaking Contact with Charge

beneath the tanks and in the tanks

• Ground rods, loops, grids• Chemical grounds• Thief hatch ground rods• Carbon C Veil• Bonding

ElectricalEquipmentProtection

Metal Oxide Varistors (MOV) TVSS (SPD) Basic Element

• Varistor = variable resistor• Resistance changes with voltage• Convert lightning energy into heat, if

properly installed• Analogous to Back Pressure Relief Valve

Current or Flow

Pres

sure

or

Vol

tage

Lim

it

Max

imum

Allo

wab

le W

orki

ng P

ress

ure

o

r In

sula

tion

Punc

ture

Vol

tage

Pressure or VoltsX

+Volts-

Current

MOV

TVSS Modes and Wires

deltaA B

C

G

A B

YThree Mode

G

A B

C

A

C G

Four Mode Six Mode

B

C

3-wire SPD (TVSS), No Ground

Effect of Long Ground Wire

Large pressure dropin long, small diameterdischarge pipe.

Pressure Relief Valve

MOV

Large voltagedrop alongground wireinductance

Voltage Impulse Pressure Impulse

Valve bypass into a small diameter discharge tube equivalent to a TVSS with long ground wire and high

ground resistance.

Wellhead Grounding

• Getting to Infinite Ground – water table?• A ground rod thousands of feet long• Ground resistance less than ONE ohm• Can the wellhead be damage by lightning?• National Electric Code (NEC) requirement

Opus 250, No. .-112M• Corrosion? AC – No, Cathodic protection

evaluation – CPET. Coexistence – Surge and Cathodic protection

Wellhead Electrical Connection

• Ground Clamps – loose, loose wire, paint and corrosion, few contact points, shock, workover crew removal and replacement?

• Cad Weld – Great connection, RR signal lights & substation ground grids, can not be removed to check wires, welding around natural gas?

• Service Post Grounding

Service Post Wellhead Grounding

Welded Bolt and Ground Lug

H1H2

H1 H1H2 H2

X1 X2 X1 X1X2 X2

Pole Butt Plate or Wrap

Transformers

Lightning Arresters

Additional groundrods as needed

Switchboard

Ground connection point

Junction orVent Box

Earth surface line

Power SystemGround

ESP Cable

Ground wire

armor ground wire

Wellhead

Wellheadgroundresistance

Inductance of pole ground wire

Inductance of pole towellhead ground wire

Butt wrapgroundresistance

0 V

10,000 V

+

Lightning atarrestercommon

Voltage at wellhead

Voltage at switchboard

Infinite Ground

Ground Wire and Wellhead Voltages

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

0.E+00 1.E-06 2.E-06 3.E-06 4.E-06 5.E-06 6.E-06 7.E-06

Time

Vo

lts

.5 Ohm5 Ohm10 Ohm20 Ohm a b c

g

gSwitchboard Mounted TVSS

a b c

Vent BoxMounted TVSS

MOV Volt Amp CharacteristicsCurrent

Volts+MOV volts

-MOV volts

Backwards

MOVvolts

G

A

B

C

MOVvolts

+ _

Lightning voltage on butt wrap

Separate Bonded Ground Wires

An Improperly Installed TVSS Can Cause ESP Damage

Indian Basin and Tatum, NM

H1H2

X1 X2 X1 X1X2 X2

Transformers

Lightning Arresters

Shield Wire(Overhead Neutral, OHN)

TVSS

H2 H2H1 H1

Reda

Cab

le

• Backward Through:

• Lightning Arresters• TVSS or Secondary Lightning

Arresters• Switchboard Mounted TVSS

H1H2

H1 H1H2 H2

X1 X2 X1 X1X2 X2

Wellhead

Switchboard

Pole Butt Plate or Wrap

Preferred Submersible Pump Grounding for Lightning Protection

Ground connection point

Junction orVent Box

a b c

g

1. Ground wires should be green THHN insulated, #2AWG stranded copper to minimizebreakage and corrosion. 2. For safety ESP cable armor must be connected to the ESP System Ground with

Transformers

Lightning Arresters#8 AWG solid copper wire as shown. Between the switchboard and poles it should beisolated from the Power System Ground. 3. Power System and ESP System ground wires should be run no closer than 6" apartto avoid sideflash. Pole ground wire and wellhead are the only permissible connectionson the Power System ground wire.

Pro-MoDr TVSS

6. A service post (Burndy K2C23B1 or Penn-Union SCS-4A1) screwed into a tapped hole between bolts in the lower flange is the recommended wellhead grounding method. A "hot work" permit will be required if natural gas is present. Connection at the lower flange should eliminate the need for groundwire removal during a workover.

Earth surface lineESP Cable

Additional groundrods as needed

4. ESP System Ground wires should connect to the ground lug on the TVSS at the junction box. The small green TVSS wire should ground the junction box internally. 5. At the junction box armors should not come in contact with each other or the metalbox to minimize ground loop interference.

ESP SystemGround, BlueTape

Power SystemGround, WhiteTape

H1H2

H1 H1H2 H2

X1 X2 X1 X1X2 X2

Wellhead

Switchboard

Pole Butt Plate or Wrap

Ground connection point

Junction orVent Box

a b c

g

Lightning Arresters

Pro-MoDr TVSS

Earth surface lineESP Cable

Additional groundrods as needed

Cable armor grounds

Armorground

Simplified Submersible Pump Grounding for Lightning Protection

1. Transformer windings to the ESP must be ungrounded.2. Power System Ground connects to the switchboard and cable armors as shown.3. Power System Ground goes directly to the wellhead without contacting the junction box.4. TVSS and Power System ground wires should be green THHN insulated, #2 AWG strandedcopper to minimize breakage and corrosion and isolated from each other to avoid sideflash.5. At the junction box armors should not come in contact with each other or the metal box.6. TVSS Ground wire should connect to the ground lug on the TVSS at the junction box.The small green TVSS wire grounds the junction box internally. 7. A service post (Burndy K2C23B1 or Penn-Union SCS-4A1) screwed into a tapped hole between bolts in the lower flange is the recommended wellhead grounding method. A "hot work" permit will be required if natural gas is present. Connection at the lower flange eliminates the need for groundwire removal during a workover.

Transformers(secondary windings ungrounded)

Power SystemGround - White& Red Tape

TVSS Ground Blue Tape

TVSS2

H1H2

H1 H1H2 H2

X1 X2 X1 X1X2 X2

Pole Butt Plate or Wrap

Transformers

Lightning Arresters

Additional groundrods as needed

Earth surface line

Power SystemGround

Disc

onne

ct

Variable Speed Drive

ESP Cable

Ground connection point

Wellhead

or

Step-Up Transformer

TVSS

1

Preferred Submersible PumpLightning Protection Grounding for Variable Speed Drives

1. Ground wires should be green THHN insulated, #2AWG stranded copper to minimizebreakage and corrosion. 2. Power system ground wire should not connect directly to the drive through conduitor the disconnect. It should go directly to the wellhead. This is critical to preventing TVSS1 from damaging the VSD and ESP when lightning strikes. Disconnect,VSD and step-up transformers are still bonded via the ESP system ground wire. 3. 480V power into VSD should be ungrounded. 4. For safety ESP cable armor must be connected to the ESP System Ground or TVSSGround with #8 AWG solid copper wire as shown. Between the switchboard and poles it should be isolated from the Power System Ground.

6. TVSS Ground wire should connect to the ground lug on the side of TVSS2 at the junction box. The small green TVSS wire should ground the junction box internally.

5. Power System, ESP System and TVSS ground wires should be isolated from each other to avoid sideflash

7. At the junction box armors should not come in contact with each other or the metalbox to minimize ground loop interference. 8. A service post (Burndy K2C23B1 or Penn-Union SCS-4A1) screwed into a tapped hole between bolts in the lower flange is the recommended wellhead grounding method. A "hot work" permit will be required if natural gas is

present. Connection at the lower flange should eliminatethe need for ground wire removal during a workover. 9. If drive is trailer mounted junction box shouldbe fiber glass for electrical isolation

Junction orVent Box

armor groundwire

Power system groundwhite tape

ESP system groundred tape

TVSS ground blue tapearmor ground wire

Ungrounded Transformer Windings

• The preferred way for 80 years• Continuous oil production through first

insulation fault• Grounding will damage cable or motor on

first fault so that ESP must be pulled• Improved lightning protection – Grounding

is to LA common• Perfectly Safe

Junction Box Mounting

• Shortest ground wire to the wellhead• On load side of switchboard contactor so

overload protection will be activated if TVSS fails

• Wellhead connects directly to the housing of the downhole ESP motor

Priority 2 – Protection of Disposal Pump Motor and Control

• A Wellhead ground is normally not available

• Connect to ground loop around tank battery

• If possible separate lightning arrester ground wire from motor and control ground wire

Ground rod (Optional)

Control box

Ground wires

TVSS

Motor Wellhead

480V, 3 phase

YEarth surface

XZ

Pow

er S

yste

m G

roun

d an

dLi

ghtn

ing

Arr

este

r Com

mon

Summary

• Charge Transfer Systems can provide improved tank battery protection. Reliability has been over 99% for 40,00 service years

• Properly designed and installed TVSS can prevent almost all equipment damage if: 4-wire TVSS are used grounded to wellhead junction box mounting ungrounded transformer windings separate ground wires

Lightning Damage can be Stopped!Science and Engineering will Ultimately Prevail

Equipment Repair and Replacement can be Reduced

Lost Production can be Minimized

A Bad Day in the Neighborhood