Oil and gas production loss waterfall
Every barrel of potential that was not produced should have a cause and an owner. This interactive demonstration shows how Inerra Impact accounts for deferred production, from budget to exported barrels and down to the trip, well or setting behind each loss, using four fictional assets in the UK North Sea, Oman and the UAE through 2025.
At a glance:
Against budget
Metered export against the budget at actual weather, of expected energy. Weather moved the budget by .
How much is explained
of the shortfall is explained by counted losses. The other , , is unexplained.
of unexplained losses, more than the whole shortfall. The counted losses are net better than budget, so the gap is a data question first.
of unexplained losses, even though this view is ahead of budget.
of unexplained losses, inside the model and meter tolerance on complete data, so this view is on budget.
How much is actionable
worse than allowance across in planned shutdowns, unplanned plant losses, well losses and optimisation: the losses operations, contractors and OEM agreements can act on. of it has no contractual owner.
Every controllable category is at or better than its allowance in this view.
Largest variance and next step
at , Main cause: , carried by , and , carried by .
Every category is at or better than its budget allowance in this view, counting paid curtailment as recovered.
Net budget (P50)
Metered against it
Budget at actual weather
Weather
Metered export
against budget at actual weather
Total losses
Expected energy less metered
Unexplained
Not accounted for by any loss
Data completeness
Weighted by expected energy
Battery round trip
against guarantee;
CHP heat delivered
against heat budget at actual demand
From budget to exported productionFrom production potential to exported productionCHP heat, from budget to heat deliveredWhere the CHP gas wentBattery round tripWhere the gas went
Each loss bar shows the result against the allowance in the budget. Up is better than budget, down is worse. Click a bar to see what is inside it.Every barrel between production potential and the fiscal meters. Click a loss bar to see what is inside it and who owns it.CHP heat in MWhth, measured inside the energy centre at the CHP heat meters after the dump radiators, so boiler heat and the network beyond the energy centre are outside it. Heat dumped through the radiators is not a bar here, because the network did not need that heat. It burned gas for no heat sale, so it is in the Fuel tab.Every MWh of gas burned, on gross calorific value, split into what came back as electricity and useful heat and what was lost, beside the engine maker's full-load figures converted to gross. A real assessment corrects them to the actual load, ambient conditions and gas quality, and applies the contract tolerance.Every MWh imported to charge the battery and run the site, split into what was exported and what was lost on the way, beside a reference split built from the round-trip efficiency guarantee and the design loss budget.Every MMscf of gas produced, split into what was exported or sold, used as fuel, reinjected, flared, vented or removed as acid gas, against the plan. Gas lift is an internal recycle, so it is not a use here. At the UK assets, gas flared above the plan is gas that was not exported, and it is a bar in the waterfall. Wadi Nur sells no gas: it burns some for power and reinjects the rest. Its north cluster gas line, which the plan had in service from January, is not yet built, so that gas is flared instead of reinjected. Reinjection compressor outages added another 15 MMscf. At Ras Sabkha, the gas flared in plant trips and restarts is traced from those events; the plant was not exporting then, so that production is already inside the trip bars.
- Totals
- Weather (degree days), not controllable
- Heat lost
- Unexplained
- Totals
- Weather and design, not controllable
- Better than budget
- Worse than budgetLoss
- Unexplained
- Largest shortfall
Low dataData completeness is here, below . Bars that look better than budget may simply be under-recorded, with the missing losses sitting in unexplained, so read them with care.
The value axis starts above zero so the loss bars stay readable; total bars carry a break mark where they are cut. Source: fictional sample portfolio, full year 2025.
Inside
Allowed ·Actual ·Against allowance
Items and owners
Click an item to see the events or measurements behind it.
Unexplained has no items, and the budget allows nothing for it. It is what is left once every counted loss and exported production are taken away from potential, so it grows when allocation and fiscal metering disagree. Compare it with data completeness in the site table.
By site
Bars show the actual loss and ticks show what the budget allowed. Click a site to drill into it. In % view each site is measured against its own expected energy.
Source: fictional sample portfolio, full year 2025.
Who owns the loss
Each loss item mapped to the party that carries it. Third-party, tanker and buyer losses can carry compensation under the transportation agreement, the charter or the sales agreement, so a real assessment records the contract position as well as the owner. Weather carries its own losses: no contract pays for them.
- Owned by a party or contract
- No contractual owner
- Unknown (unexplained)
Source: fictional sample portfolio, full year 2025.
When they happened
Each dot is one event, sized by what it lost. Click a dot or a row to open it.
Events, largest first
| Start | Site | Asset | Root cause | Duration | Lost | Status |
|---|
By asset
By month
Click a month to set the period.
How it is measured.
Times are site local time. Source: fictional sample portfolio, full year 2025.
Losses by month
Every loss category, month by month, with the total the budget allowed marked on each bar. Click a month to set the period, and click it again to go back to the whole period. Click a category in the key to open it.
Source: fictional sample portfolio, full year 2025.
Sites
Sorted by result against budget at actual potential, worst first. Click a row to drill into the asset. Production efficiency is exported production against potential.
| Site | Asset | Potential (kboe/d) | Budget at actual potential (kboe) | Exported (kboe) | Against budget | Losses | Unexplained | Data completeness | Production efficiency |
|---|
Source: fictional sample portfolio, full year 2025.
Method, definitions and sample data
- Net budget
- Production the 2025 business plan expected each asset to export, after the losses it allows for in each category.
- Reservoir and new wells
- The change in budget because the reservoir and new wells delivered more or less potential than the plan: decline, water breakthrough and new wells coming on late. At Halsay FPSO a new tieback well came on in mid-June against an April plan, and at Wadi Nur infill wells were late in the first four months. It is a reservoir and well delivery result rather than an operating loss, so it is shown in grey.
- Production potential
- What the asset could have exported with every well, train and export route available. It starts from well tests at optimum conditions, converted to export conditions with the allocation shrinkage factors, less the fuel gas, planned flare, reinjection and acid gas that rate needs. Gas flared above the plan is then a loss bar at the UK assets, so every boe from the wells is accounted for.
- Production efficiency
- Exported production against this potential. On the NSTA basis, which takes designed-in facility limits out of potential and counts fuel, flare and vent as production, Corran Alpha reads 80.8% against 79.2% here (0.9 points from facility limits, 0.7 from own use), and Halsay FPSO 86.4% against 85.3% (0.6 points from facility limits, 0.5 from own use). The UK offshore average on the NSTA basis was 76% in 2025, so the 1990s Corran Alpha sits 4.8 points above it and the newer Halsay FPSO 10.4 points above it. In 2021 only 31% of UK hubs reached 80%.
- Allocation
- Each loss is booked to the cause behind it. Where a shutdown was aligned with the export system's, it stays a planned shutdown. A full stop of the whole site takes all of its potential while it lasts, so continuous losses count only the hours the site was producing, and an event on one machine or well leaves out the hours its whole site was already down. Partial events that overlap are each counted at their own rate; in this sample that overlap comes to about 0.16% of potential. Whatever remains is unexplained, usually allocation and metering differences.
- Allowances
- Each category's allowance is a share of potential. Planned turnarounds and planned maintenance sit in the month the plan has them, at their planned duration, so a month carries the allowance for the work planned in it. Planned shutdowns then read worse than allowance only when work overran. A turnaround overrun counts as planned shutdown, as the NSTA books it, against no allowance of its own.
- Gas view
- Gas produced split into gas exported or sold, fuel gas, reinjected, flared, vented and acid gas removed, against the plan. Fuel gas is largely fixed, so it runs per producing day whatever the rate, and diesel replaces it in a full shutdown. Gas lift is an internal recycle and comes back with the well stream, so it is not counted as a use. Ras Sabkha's routine flare is sweet pilot and purge gas, about 0.25% of gas produced; raw sour gas reaches the flare only when a trip depressurises, and is never cold-vented, so it vents no hydrocarbons. Acid gas, sulphur and process CO2 are worked out on the gas the plant processed, and the SO2 from sour gas flared is shown. The CO2 removed from its gas is counted separately as process CO2, and acid gas flared while a sulphur recovery unit is down comes off the sulphur recovered. Flaring above plan is traced from the trips and restarts at the UK assets and Ras Sabkha; only trips that depressurise (gas detection, leaks, loss of instrument air or main power) add a blowdown. Emissions use fixed factors of 60 t CO2e per MMscf of fuel gas and 75 per MMscf flared (98% combustion, 2% methane slip) for the rich associated gas burned on site; at Ras Sabkha 55 for the sweet gas it burns and flares routinely and 66 for raw sour gas flared in trips; 430 per MMscf vented (80 mol% methane), 52.6 t per MMscf of CO2 removed and 2.7 t per m3 of diesel, with methane at a GWP of 28 (IPCC AR5, as the NSTA uses). Gas is priced at a sales gas heating value of 1,035 Btu/scf. UK flaring also pays for UK ETS allowances on its CO2 (66.4 t per MMscf), at £49.41 a tonne, the average over the 12 months to November 2025. A real assessment uses gas composition and measured flare efficiency.
- Netback view
- Each boe at the asset's 2025 netback after transport, tariffs and quality differentials: Brent averaged $69 a barrel and Murban $69.76, Oman's average realised price was $72, and NBP gas was about 88p a therm, at $1.32 to the pound. Ras Sabkha's gas sells at a contract price of $2.50 per MMBtu, so its blend of gas and condensate earns about £30 per boe against £49 at Corran Alpha, and the same volume weighs less there.
- Events
- Trips, outages, failed pumps and shut-in wells are listed one at a time with the equipment or well, dates, root cause, owner and evidence. They add up exactly to the item above them. An outage that runs into the next month is carried into it under the same id, with each month's share of the loss in that month. Event volumes are shown in barrels of oil equivalent.
- Response target
- Trips the operations crew can clear are restarted with no call-out. When a part or a specialist is needed, the target is 48 hours offshore and 24 hours onshore for an OEM field service engineer, and 7 days for a workover hoist on a failed ESP, in this sample. A failed ESP is two events: the well waiting for the hoist, which is the operator's, then the change. The ESP vendor carries the change for motor and cable failures and while the teardown is pending; sand, scale and restarts against the operating instructions are the operator's. The change takes 2 to 4 days once the hoist is rigged up, and longer from June to August, when Oman's midday outdoor work ban stops work from 12:30 to 15:30.
- Data completeness
- The share of allocation intervals with valid fiscal meter and well test data, weighted by potential.
Sample data. The four assets, their names, allowances, events and every number on this page are fictional, generated to show how the waterfall behaves. The UK production efficiency average is from the North Sea Transition Authority. Oil prices and NBP are 2025 market averages; Ras Sabkha's gas price is assumed; everything else is invented.