Gauge sheets

A gauge sheet in this platform is a record of one observation of one tank at one time, plus everything needed to turn that observation into a defensible volume.

Innage and outage

Both are first class. Neither is converted into the other for storage.

• Innage is liquid depth measured up from the tank’s datum plate.
• Outage (also called ullage) is the distance measured down from the tank’s reference gauge point to the liquid surface.

Different crews and different tanks are gauged different ways. Forcing one convention is how you get bad data, because someone ends up converting in their head at the tank.

Outage converts through the tank’s recorded reference height:

innage = referenceHeight − outage

A tank with no recorded reference height cannot accept outage entry. The app says so rather than guessing a height.

The raw observation is retained exactly as recorded, along with which method produced it.

Units

Readings are entered in the units the crew actually gauges in — feet, inches and eighths, or decimal inches. Both are stored: the raw entry as typed, and the normalized value derived from it.

Nobody converts in their head. That class of arithmetic error is precisely what this feature exists to remove.

Observation time

The capture time is the pumper’s observation time, recorded on the device when the reading is taken. The time the record reached the server is stored separately.

Offline entry makes these diverge by hours. Conflating them corrupts every interval calculation downstream, so the platform keeps them apart and always uses observation time for interval maths.

Strapping tables

A strapping table maps gauge height to volume in barrels for exactly one tank, produced from a physical strapping survey of that vessel.

Operators supply their own tables. A strapping table describes one specific physical tank; no library can know the geometry of yours.

Rules the platform applies:

• Values between table entries are linearly interpolated, and the resulting volume is marked as interpolated. An exact table hit and an interpolated value stay distinguishable.
• A reading outside the table’s bounds is rejected with an explanation, never extrapolated.
• Tables are versioned with an effective date. Re-strapping a tank creates a new version; it never edits the old one. A gauge is always evaluated against the table version in effect at its observation time, so recomputing history does not silently restate it under a newer table.
• Table provenance records who supplied it and when.

A tank with no table is visible in the app as unmeasurable, not absent. Gauges can still be recorded against it, and volumes compute as soon as a table is loaded.

Hauled loads

Production since the last gauge is the volume change plus what left on a truck:

produced = (V_current − V_prior) + Σ hauledVolume(interval)

Without haul accounting, a tank that got trucked produces a negative volume change and the interval reads as negative production.

What a haul record requires

Volume is the only required field. A crew that wants to move fast enters one number.

Full ticket detail is optional and captured at the operator’s discretion: ticket or manifest number, carrier, destination, and load time. Both paths produce the same corrected production figure. One simply carries more history with it.

How hauls are attributed

A haul belongs to the interval containing its load time, not the interval it happened to be entered in. A haul entered late reopens and recomputes the affected interval under the correction rules below.

For oil and condensate, a run ticket usually carries both gross and net volumes. Record both where available; the net volume is used for the production calculation.

Negative production

A haul that would drive computed production negative is flagged, not clamped and not hidden. It usually means a missing gauge, a mis-keyed volume, or a load attributed to the wrong tank. Surfacing it is more useful than absorbing it.

Corrections

A pumper can amend an earlier gauge, haul or measurement input from the field.

• The original record is retained. A correction is a new record referencing the original, capturing author, time and reason. Nothing is overwritten and nothing is deleted.
• The current value of any reading is its latest accepted correction, and history stays reconstructible as of any point in time.
• Amending a record recomputes every derived volume that depended on it, including intervals that were already closed.
• Recomputed figures that changed are flagged as restated, not silently replaced. A production number someone already acted on does not get rewritten behind their back.

What a gauge does and does not tell you

A gauge measures a tank. A tank sits on a battery. A battery commonly serves several wells.

Derived volumes are reported at the tank and battery level. The platform does not split a battery volume across the wells it serves, because that is an allocation decision with real consequences for how defensible the resulting number is.

Next: volume correction for how a strapped volume becomes a net standard volume, and measurement sources for where temperature, gravity and BS&W come from.