How to Automate a Tank Battery
Key Takeaway
Automating a tank battery involves installing level transmitters on stock and water tanks, flow meters on sales and disposal lines, motorized test valves for automated well testing, a PLC or RTU for local control, and communication equipment for remote monitoring. A fully automated tank battery eliminates manual gauging, automates well test scheduling, and provides real-time production data for every connected well.
Why Automate a Tank Battery?
The tank battery is the nerve center of a lease. It's where production from multiple wells is gathered, separated, measured, stored, and transferred. Manual tank battery operations require daily gauge readings, hand-written run sheets, and periodic well tests that take pumpers hours to set up and monitor. Automation transforms this into a continuous, real-time data stream.
Key Benefits
- Eliminate manual tank gauging (2-3 hours/day per battery saved)
- Automated well testing on a programmed schedule (no setup, no waiting)
- Real-time tank levels prevent overflows and truck scheduling surprises
- Instant leak detection via level rate-of-change monitoring
- Accurate production allocation by well without manual calculation
- LACT unit data transmitted automatically for run ticket reconciliation
Step 1: Instrumentation
Tank Level Measurement
Install level transmitters on every tank:
- Stock tanks (oil): Radar (guided wave or FMCW) level transmitters are preferred for oil service. They handle foam, vapor, and interface detection. Typical models: Endress+Hauser Levelflex, Emerson Rosemount 5300.
- Water tanks: Ultrasonic or hydrostatic pressure transmitters work well for water. Less expensive than radar. Typical models: Siemens Sitrans LU, Endress+Hauser Prosonic.
- Gun barrel / treater: Interface level detection (oil/water/emulsion) using guided wave radar with dual-probe capability or capacitance probes.
Flow Measurement
- Test separator: Gas orifice meter, oil Coriolis or turbine meter, water turbine meter on the test side of the separator
- Sales oil: LACT unit Coriolis meter (custody transfer grade, typically ±0.05% accuracy)
- Water disposal: Magnetic or turbine flow meter on the water disposal line
- Gas sales: Orifice or ultrasonic meter on the sales gas line with pressure and temperature compensation
Pressure and Temperature
- Separator operating pressure
- Header pressure (upstream of test valve manifold)
- Treater temperature
- LACT unit pressure and temperature for volume correction
Step 2: Test Valve Manifold
The test valve manifold is what enables automated well testing. Each well's flowline connects to a motorized valve that routes flow either to the production side (normal) or the test side of the separator.
- Valve type: Electric or pneumatic motorized ball valves (typically 2" or 3" depending on flow rates)
- Position feedback: Each valve needs open/closed limit switches wired to the PLC for confirmation
- Test sequence: PLC cycles through wells automatically — opens test valve for Well 1, waits for stabilization (30-60 min), records test data, closes valve, moves to Well 2
- Scheduling: Configurable test frequency per well (daily, every 3 days, weekly) with priority scheduling for problem wells
Step 3: PLC/RTU and Control Panel
The local controller handles all tank battery logic:
- Hardware: Allen-Bradley CompactLogix 5380, Emerson ROC800, or ABB RTU560 depending on complexity and existing infrastructure
- I/O count: Typical automated tank battery requires 20-40 analog inputs, 10-20 digital inputs, and 8-15 digital outputs
- Control functions: Well test sequencing, pump control (level-based start/stop), high-level shutdown, LACT proving, and alarm generation
- Panel: NEMA 4X rated enclosure with climate control (heater/cooler) for electronics protection in field environments
Step 4: Communication
Connect the tank battery to your SCADA system:
- Primary: Cellular modem (LTE) or licensed radio to SCADA host
- Protocol: Modbus TCP, DNP3, or OPC UA depending on your SCADA platform
- Polling rate: 10-60 second scan rate for real-time monitoring
- Local wells: Wellsite RTUs can communicate to the tank battery PLC via radio, then the tank battery PLC communicates to the SCADA host — reducing the number of cellular connections needed
Step 5: SCADA Integration
Configure your SCADA platform with:
- Tank battery overview screen (tank levels, flow rates, pressures at a glance)
- Well test results display (last test date, rates, cumulative totals)
- Alarm configuration (high level, low level, pump failure, test valve fault)
- Historical trending (tank level over time, production rates, water cut)
- Report generation (daily production report, well test report, truck loading report)
Typical Costs
| Component | Estimated Cost |
|---|---|
| Level transmitters (4-6 tanks) | $8,000 - $15,000 |
| Flow meters (test + sales) | $15,000 - $30,000 |
| Motorized test valves (6-10 wells) | $12,000 - $25,000 |
| PLC, I/O, and control panel | $15,000 - $25,000 |
| Communication equipment | $3,000 - $8,000 |
| Installation and commissioning | $20,000 - $35,000 |
| Total | $73,000 - $138,000 |
ROI is typically achieved within 8-14 months through labor savings, improved production allocation, and reduced truck scheduling inefficiencies.
Frequently Asked Questions
A typical automated tank battery handles 4-12 wells, limited by the separator capacity and the number of test valve positions in the manifold. Larger batteries with multiple separators can handle 20+ wells. The automation system scales easily by adding more I/O modules and test valves.
A LACT (Lease Automatic Custody Transfer) unit is required for automated custody transfer oil sales to a pipeline. If you sell oil by truck loading, you can use a simpler metering system. However, LACT units provide the highest accuracy (±0.05%) and are required by most pipeline purchasers for continuous delivery. The LACT unit integrates with the tank battery automation system for seamless reporting.
Yes. Automated well testing (motorized test valves + separator metering + PLC) can be installed as a standalone project. This gives you accurate per-well production data without fully automating tank levels and LACT operations. Many operators start here and expand automation later. Cost for test-only automation: $30,000-$60,000 depending on well count.