St o p p i n g O i l f i e l d Li g h t n i n g Da m a g e
You can not stop lightning!
True. But you can stop the damage it does! An Engineering Approach
You can not stop lightning!
True. But you can stop the damage it does! An Engineering Approach
Oil Production Priorities • Tank Tank Bat Batte teri ries, es, doe does s NFP NFPA A 780 780 reall really y apply? • Dis Dispos posal al pum pump p mot motors ors and co cont ntrol rols s • Ele Elect ctri ric c Sub Subme mers rsibl ible e Pum Pumps ps,, ESP ESP,, does API RP11S really apply? • ES ESP P Vari Variab able le Fre Frequ quen ency cy Dr Driv ives es • Pum Pumpin ping g uni unitt mo moto tors rs and co cont ntrol rols s
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
Each, 1000 Barrels 15'-5" dia, 30' high Fiber glass, gun barrel, water sep.
125 HP SWD Motor
500 HP SWD Motor Disposal Well 150' East
catwalk
Rolling Sphere Calculation 74 foot diameter
Knockouts, steel 10' dia x 20' long & 10' dia x 15' long
Vertical Gas Separator 3' dia x 12' high
Oil Storage 300 Barrel 12' dia, 15'-5" high Steel Each
k l a w t a c
h t r o N
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
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_ _ _ _ _ _ _ _ _ _ _ _ Winning the Competition
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Grounding Making Contact with Charge beneath the tanks and in the tanks • • • • •
Ground rods, loops, grids Chemical grounds Thief hatch ground rods Carbon C Veil Bonding
Electrical Equipment Protection
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
Current or Flow t i m i L e g a t l o V r o e r u s s e r P
+ Volts MOV Pressure or Volts X
e r u s s e r e g P t a g l o n V i k e r o r u t W e c l n b u a P w n o i l o l t A l a m u u s n I m i r x a o M
TVSS Modes and Wires A
B
B
A
delta
G
Y
Three Mode C
C B
A
A
B G
C
Four Mode
G
C
Six Mode
3-wire SPD (TVSS), No Ground
Effect of Long Ground Wire Voltage Impulse
MOV
Large voltage drop along ground wire inductance
PressureImpulse Pressure Relief Valve
Large pressuredrop in long, small diameter discharge pipe.
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
Lightning Arresters H1 H2
X1
X2
H1
H1
X1
H2
H2
X2
X1
X2
Transformers Power System Ground
Switchboard Wellhead
Junction or Vent Box
Ground wire Earth surface line ESP Cable armor ground wire
Pole Butt Plate or Wrap Additional ground rods as needed
Ground connection point
Inductance of pole ground wire
10,000 V
0V
Lightning at arrester common
+
Voltage at switchboard Butt wrap ground resistance
Infinite Ground
Inductance of pole to wellhead ground wire
Voltage at wellhead Wellhead ground resistance
Ground Wire and Wellhead Voltages 9000
8000
7000
g 6000
a b c 5000
s t l o V
Switchboard Mounted TVSS
4000
3000 .5 Ohm 5 Ohm
2000
10 Ohm
Vent Box a b c Mounted TVSS
20 Ohm
1000
g
0 0.E+00
1.E-06
2.E-06
3.E-06
4.E-06 Time
5.E-06
6.E-06
7.E-06
MOV Volt Amp Characteristics Current
-MOV volts
Backwards
Volts
+MOV volts
Lightning voltage on butt wrap
A
B
G MOV volts
C +
_ MOV volts
Separate Bonded Ground Wires An Improperly Installed TVSS Can Cause ESP Damage Indian Basin and Tatum, NM
Shield Wire (OverheadNeutral, OHN)
• Backward Through: • • •
Lightning Arresters H1 H2
X1 X2
H1
H2
H1
X1 X2
H2
X1 X2
TVSS
Transformers
e l b a C a d e R
Lightning Arresters TVSS or Secondary Lightning Arresters Switchboard Mounted TVSS
Preferred Submersible Pump Grounding for Lightning Protection 1. Ground wires should be green THHN insulated, #2AWG stranded copper to minimize breakage and corrosion. 2. For safety ESP cable armor must be connected to the ESP System Ground with #8 AWG solid copper wire as shown. Between the switchboard and poles it should be isolated from the Power System Ground. 3. Power System and ESP System ground wires should be run no closer than 6" apart to avoid sideflash. Pole ground wire and wellhead are the only permissible connections on the Power System ground wire. 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 metal box to minimize ground loop interference.
Lightning Arresters H1 H2
X1
X2
H1
H1
X1
X2
X1
Transformers
Switchboard Wellhead
ESP System Ground, Blue Tape Junction or Vent Box
a b c g
Pro-MoDr TVSS
Power System Ground, White Tape
Earth surface line ESP Cable
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 ground wire removal during a workover.
H2
H2
Pole Butt Plate or Wrap Additional ground rods as needed Ground connection point
X2
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 stranded copper 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 ground wire removal during a workover. Switchboard
Lightning Arresters H1
H1
H1
H2
X1
X2
X1
X2
X1
Transformers (secondary windings ungrounded)
Wellhead
Armor ground
TVSS Ground Blue Tape a b c
Junction or Vent Box
g
Pro-MoDr TVSS
H2
H2
Power System Ground - White & Red Tape
Cable armor grounds
Earth surface line ESP Cable
Pole Butt Plate or Wrap Additional ground rods as needed
X2
Preferred Submersible Pump Lightning Protection Grounding for Variable Speed Drives
Lightning Arresters H1 H2
X1
X2
H1
H1
H2
H2
X1 X2
X1
X2
Transformers Power System Ground
t c e n n o c s i D
1. Ground wires should be green THHN insulated, #2AWG stranded copper to minimize breakage and corrosion. 2. Power system ground wire should not connect directly to the drive through conduit or 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 TVSS Ground with #8 AWG solid copper wire as shown. Between the switchboard and poles it should be isolated from the Power System Ground. 5. Power System, ESP System and TVSS ground wires should be isolated from each other to avoid sideflash 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. 7. At the junction box armors should not come in contact with each other or the metal box 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 eliminate the need for ground wire removal during a workover. 1 9. If drive is trailer mounted junction box should S Wellhead S be fiber glass for electrical isolation V T
Variable Speed Drive
armor ground wire Step-UpTransformer
or
Junction or Vent Box ESP Cable
Earth surface line
TVSS groundblue tape Pole Butt Plate or Wrap Additional ground rods as needed
armorgroundwire
Ground connection point
Power systemground white tape
ESP systemground redtape
TVSS2
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
480V, 3 phase
n d o m n a m d o n C u r o e r t G s e r m r e t A s y g n S i r n e t h w g o i P L
Control box
TVSS
Motor
Wellhead
Earth surface Z
Ground wires Ground rod (Optional)
Y
X
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
