LACT Unit PLC and Meter Proving Integration for Producers
Key Takeaway
LACT PLC integration ties custody-transfer meters, BS&W, temperature, proving sequences, and battery permissives into reliable sales. Producers lose money on bad cutovers, stuck provers, and SCADA tags that do not match ticket volumes.
Quick Answer
Lease Automatic Custody Transfer (LACT) automation is where production becomes money. The PLC (or flow computer + PLC) must coordinate meter pulses, BS&W probes, densitometer and temperature inputs, charge pump permissives, and proving — then publish trustworthy totals to SCADA and accounting.
PLC responsibilities vs flow computer
- Flow computer / Coriolis transmitter: Often owns custody math and API MPMS volume correction for liquid sales (gas measurement uses AGA methods where applicable).
- Pad/facility PLC: Owns battery ready, tank selection, pump start/stop, ESD permissives, and SCADA packaging.
- Hybrid sites: Clear handshake bits so neither side assumes the other is “watching.”
Proving sequence pitfalls
- Prover valves without confirmed feedback.
- Timeouts too short for cold oil or long piping.
- SCADA writes that interrupt a prove mid-cycle.
- Missing audit trail of prove factors and who accepted them.
Coordinate with tank battery PLC programming and LACT unit automation so LACT enable cannot fire into a full or offline battery path.
Field work that protects tickets
I&E scope includes meter pulse wiring integrity, grounding that does not inject noise into turbine/Coriolis signals, temperature element placement, and BS&W sample system health. Controls scope includes sequence logic and historian tags finance trusts. Producers hire teams that own both — NFM oil and gas automation plus I&E commissioning — because ticket disputes are expensive.
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Frequently Asked Questions
Many skids ship with a flow computer that handles custody math. A facility PLC is still common for pump control, battery permissives, ESD, and SCADA integration. Define ownership so proving and sales enable are not split ambiguously.
Gross and net rates/totals, BS&W, temperature, prove status/factor, charge pump run, valve positions, and inhibit reasons. Operators also need a clear not-ready cause — not a single red fault bit.
Verify permissives with the battery offline path blocked, dry-run valve sequences, confirm meter pulse scaling against a known prove or simulated input, and document fail positions before first sales oil.
Still have questions about your setup? Talk to an engineer or call (210) 405-4248.