One of the first lessons learned in wireline services oil and gas is that safety isn’t just a guideline—it’s a lifeline. In the field, even the smallest stray voltage can turn a routine job into a dangerous situation, especially when dealing with wireline perforating, logging cables, or pressure control equipment.
A job once required setting up for a cased hole wireline operation to perform perforation services. Everything seemed normal—until a last-minute check revealed unexpected voltage between the wireline cable and the wellhead.
Had this gone unnoticed, it could have caused an electrical discharge near explosive-loaded perforating guns—a risk no wireline provider should ever take.
Why Stray Voltage Checks Matter in Wireline Logging
Cased hole logging, pump down perforating, and well perforation operations involve sensitive wireline tools that must be properly grounded. A stray voltage left unchecked can:
- Trigger unintentional detonations in perforating operations
- Damage wireline control systems and logging cables
- Pose electrocution hazards to personnel handling wireline equipment
- Compromise well integrity and cause operational delays
To ensure safety in wireline well logging and perforating services, a stray voltage testing procedure is always required before explosive operations.
How to Perform a Stray Voltage Check in Wireline Operations
To comply with API RP-67 standards, every wireline service company should follow a systematic approach to checking for stray voltage before beginning cased hole solutions, perforation well operations, or production logging services.
Equipment Needed:
- Digital Multimeter to detect AC/DC voltage readings between different points
- File and Emory Cloth to ensure clean contact points for accurate readings
- Ground Clamps to be tested for proper continuity
Method for Stray Voltage Checks:
- Verify that ground clamps are properly connected by measuring resistance from the clamp to the cable connection
- Ensure an acceptable reading of less than 0.5 ohms to confirm proper grounding
- Check for stray voltage between the wireline cable and the ground clamp
- Check for stray voltage between the wireline cable and the crane or rig
- Check for stray voltage between the wireline cable and the wellhead
- Ensure clean contact points by using a file or emory cloth to remove rust, dirt, or paint before taking measurements
- Ensure all voltage readings are below 0.25 volts
- Identify and eliminate any source of voltage exceeding 0.25 volts before proceeding with operations
- Perform stray voltage checks at least once per shift for 24-hour wellsite operations
Real-World Application in Wireline and Perforating Services
On the job where stray voltage was detected, immediate actions were taken:
- Double-checked grounding clamps and found that one had been improperly attached to a painted surface instead of bare metal
- Cleaned the contact points and rechecked the readings—this time, they were within the safe range
- Verified wireline control systems before resuming the perforation services operation
If this had been skipped, it could have resulted in wireline perforating gun malfunctions, damage to the wireline truck, or worse—an uncontrolled ignition of perforating charges.
Lessons Learned in Wireline Well Logging and Cased Hole Wireline
Since adopting a strict stray voltage testing procedure, results have shown:
- No electrical-related misfires in perforating operations
- Improved wireline equipment lifespan due to reduced electrical stress
- Enhanced safety compliance with wireline service market regulations
For any wireline service provider, staying ahead of potential hazards is what separates a good job from a catastrophic failure. If working with perforating systems, pressure control equipment, or wireline logging tools, always remember:
- Test your ground
- Check for stray voltage
- Never assume everything is safe until verified
Because in the wireline oilfield, the step that is skipped could be the one that costs everything.