Crude storage tank

If the tank and the meters disagree, one of them is wrong. The twin tells you which.

Every barrel that comes in should either still be in the tank or have gone out through a meter. The level, the temperature, the water bottom and the roof all change how many barrels the tank really holds. The twin does that sum every day and says which reading has started to drift.

100,000 bbl external floating roof, 120 ft diameter, radar level, average temperature

Built and run to API 650, API MPMS Chapter 3, API MPMS Chapter 11.1, API MPMS Chapter 12.1

Start with one station or field See how we prove results

Capacity: 100,522 bbl
One inch of level: 168 bbl
VCF at 95 °F: 0.9834
Roof adjustment: 1,025 bbl

Anatomy and nameplate

1Primary level. Radar on a still pipe. Read against the strapping table.
2Secondary level. An independent gauge. The two should agree.
3Average temperature. Several points up the tank, averaged over the liquid.
4Water bottom. Free water is taken out before the oil is counted.
5Roof position. The roof displaces crude while it floats. A tilt points to a stuck seal or a pontoon leak.
6Inlet meter. Barrels received from the field.
7Outlet meter. Barrels delivered to the pipeline.

Crude storage tank nameplate
Tank
Type	External floating roof, welded steel, pontoon roof
Size	120 ft diameter, 7 courses of 8 ft
Capacity at safe fill	100,522 bbl at 50 ft
Barrels per inch	167.4 in the bottom course, 167.7 at the top
Roof	300,000 lb, lands on its legs at 6 ft
Instruments	Radar level on a still pipe, second level gauge, multi-point average temperature, water interface
Crude
Gravity	35° API, relative density 0.8498 at 60 °F
Density at 60 °F	849.0 kg/m³
Expansion coefficient α₆₀	4.732 × 10⁻⁴ per °F
Sediment and water	0.3%
Worked gauge, 46 ft at 95 °F
Total observed volume	92,471 bbl
Free water	997 bbl at 0.5 ft
Shell correction CTSh	1.00040
Floating roof adjustment	−1,025 bbl
Gross observed volume	90,486 bbl
Volume correction factor	0.98336
Net standard volume	88,713 bbl at 60 °F

From the well to market

Wells lift the fluid. The separator splits it. Oil goes to the tank battery and gas to the compressor station, and both leave by pipeline for processing.

Well fluid
Crude oil
Gas
Has its own twin page

The physics

The equations behind every curve on this page.

Gross volume

GOV = (TOV − FW)·CTSh − FRA

Strapping table at the gauged level, less water, corrected for shell temperature and the roof.

Volume correction

VCF = exp[−α₆₀·ΔT·(1 + 0.8·α₆₀·ΔT)]

Brings warm crude back to 60 °F. α₆₀ = 341.0957 / ρ₆₀² for crude.

Net standard volume

NSV = GOV·VCF·(1 − S&W)

The barrels that get counted.

Daily balance

receipts − deliveries − ΔInventory

Should wander around zero. A trend means a reading is wrong.

Balance and gauges

The balance shows that something is wrong. The pattern shows which reading it is.

Daily balance, with a receipts meter drifting

40,000 bbl/d through the tank, net standard barrels

Receipts − deliveries − ΔInventory
Running total (right axis)

Drift at full: 0.25%, 100 bbl/d
Gap over 60 days: 2,449 bbl

A healthy balance wanders around zero. A meter that drifts adds a gap that grows with the barrels it measures. A leak takes barrels whether oil is moving or not. A gauge that drifts moves the inventory, not the flows.

imbalance = receipts − deliveries − ΔNSV

Primary against secondary level gauge

Radar against a second independent gauge on the same tank

Gauge difference
In barrels (right axis)

One inch at this level: 168 bbl
A quarter inch: 42 bbl

Two gauges that read the same level should agree. When one walks away from the other, the balance starts to drift with it. A quarter inch on a tank this wide is a truckload of crude.

ΔV = (π/4)·D²·Δh

Temperature

Crude grows as it warms. The same oil counts as fewer barrels once it is brought back to 60 °F.

Temperature effect on volume

35° API crude, 90,486 bbl gross observed

VCF
Net barrels at 60 °F (right axis)

α₆₀: 4.732 × 10⁻⁴ per °F
2 °F error, this tank: 86 bbl

Warm crude takes more room. The same oil is fewer barrels at 60 °F than it looks in the tank, so the average temperature element matters as much as the level.

VCF = exp[−α₆₀·ΔT·(1 + 0.8·α₆₀·ΔT)] α₆₀ = 341.0957 / ρ₆₀²

Failure modes

What breaks, what it looks like, what the twin does about it.

Failure mode	The physics	Signals that show it	How the twin catches it
Level gauge drift	A radar loses its reference or a float tape slips, so the level reads off by a fixed or growing amount.	Primary and secondary gauges split. Balance shifts when the tank is still.	Compares both gauges every reading and the balance on days with no flow.
Meter drift	Wear or a changed fluid moves the meter factor away from its last proving.	Balance gap that grows with the barrels through that meter.	Splits the gap by receipts and deliveries to say which meter it follows.
Leak	Oil leaves through the floor, a valve or a drain without passing a meter.	Negative balance whether or not oil is moving. Level falls while the tank is shut in.	Holds the level against the model while the tank is idle and flags any loss above gauge noise.
Roof tilt or seal issues	A stuck seal or a pontoon taking on liquid tilts the roof.	Roof position sensors disagree. Level jumps as the roof frees itself.	Watches roof readings against level and flags a roof that is not floating level.
Water build-up	Water settles out of the crude and collects at the bottom.	Interface level rising. Net volume falls while gross volume stays.	Tracks free water against draws and tells you when the bottom needs draining.

What the twin does not do

The twin flags a balance gap. Custody transfer stays with certified meters and your measurement team.
We are not your overfill protection. High-level alarms and shutdowns stay independent. TwinEdge is never in the safety loop.
We do not change meter factors or tank tickets.

How we catch it early

A physics twin and a PINN, working on one crude storage tank.

The twin is a set of equations for this machine, tuned to its nameplate. Give it the flow, speed and conditions and it returns what every reading should be. It always gives the same answer for the same inputs.

A physics-informed neural network, or PINN, sits on top. It is trained on the plant’s own data and it is penalized whenever it breaks a physics rule. So it can only learn what the equations leave out: wear, fouling, friction. It cannot invent an answer that the machine could never produce.

Step 1
Measure
Flow, pressure, current, temperature, vibration. Whatever the asset already has.
Step 2
Physics twin
The equations of this machine, set to its nameplate. It says what the readings should be right now.
Step 3
Residual
Measured minus expected. Demand, weather and speed are already taken out.
Step 4
PINN
A small neural network that learns the cause of the gap, under the physics rules.
Step 5
Finding
A named cause, a date, and the kWh or hours at stake. An engineer reviews it.

loss = (measured − predicted)² + λ · (physics residual)²

The second term is the rulebook. It is zero when the network obeys the equations.

Why this beats black-box AI

A black-box model learns patterns from history. It needs examples of each failure, and it goes quiet when the pump runs at a point it has not seen. The twin starts from physics, so it works on day one. The PINN adds what physics cannot know about this particular machine.

That is also what makes the savings countable. The baseline is a calculation, not a guess, so the gap between baseline and meter is a number a customer can check.

What the twin checks on this asset

Daily balance in net standard barrels
Primary against secondary level
Gap split by receipts, deliveries and idle time
Water bottom and roof position against level

	Fixed alarm	Black-box AI	Twin + PINN
Needs failure history to learn	No	Yes, lots	No
Says what is wrong	No	Rarely	Yes, by name
Works at a flow it has never seen	No	Often fails	Yes, the equations still hold
Puts a number on the saving	No	No	Yes, in kWh and dollars
Lead time on slow wear	Late	Varies	Weeks to months
Every number can be traced	Yes	No	Yes, to an equation

What the twin puts a number on

Energy and cost, from the equations.

One inch of level

168 bbl

A quarter inch is 42 bbl

Temperature 2 °F off

86 bbl

$6,053 at $70 per bbl, on one full tank

Meter reading 0.25% high

100 bbl/d

$7,000 a day of barrels nobody has

Found by the twin

Day 35

5 days after the meter starts to drift

What we do for you

We watch it. We catch it. We prove it.

Our reliability engineers run the twin on your crude storage tank, review every finding, and help your crew fix it. After the repair we compare the meter to the baseline and write the result in the ledger.

Start with one station or field See the 90-day pilot

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