Analysis
Petrobras’s 30 September Codajás release describes preventive logistics for falling river levels, including extended storage at Coari and dedicated vessels supporting deliveries and the movement of Urucu production. It supplies context for inventory planning, not the numerical inputs below. Neither those arrangements nor a vessel’s storage capacity reveal actual contemporaneous throughput or autonomy. A published capacity cannot simply be inserted as an observed daily arrival rate.
Consider an independent, hypothetical equivalent-liquid system using one consistently defined cubic-metre basis. Initial physical inventory I0 is 5,000 m³; a protected safety reserve R is 1,000 m³. Only 4,000 m³ is usable before that threshold is reached. Assume demand d of 1,000 m³/day and net arrivals a of 800, 600 or 400 m³/day. The balance is I(t)=I0+(a−d)t, with time measured in days and losses assumed zero.
For arrivals below demand, time to the safety-reserve threshold is (I0−R)/(d−a). The three cases give 20, 10 and approximately 6.67 days. These are times until physical stock reaches 1,000 m³, not times until the tank is empty. If the same rates continued and the protected reserve were consumed, total stockout would instead occur after 25, 12.5 and approximately 8.33 days. Spending the reserve changes the operating policy; it does not make the original buffer larger.
Arrival and withdrawal rates must describe the same system, product basis and observation period. This example combines neither LPG tonnes with crude-oil cubic metres nor liquids with gas volumes; it assumes no density or conversion factor and represents no Codajás cargo. Constant demand and arrivals ignore stochastic deliveries, navigation delays and discrete ship unloading. If a is at least d, this loss-free model has no finite drawdown time to the lower reserve threshold. Actual data would require aligned flows, starting stock and uncertainty before estimating an operating margin.
Preserving a buffer may protect service continuity, but the model contains no evidence about the economic value of avoiding disruption. Holding inventory can tie up capital and incur handling, storage or product-loss costs; their size depends on actual prices, financing, facilities and product characteristics, all unknown here. It would therefore be unjustified to assign profit or project NPV to these days. Autonomy is a conditional stock-to-flow calculation, not a forecast, and resilient transport does not itself establish growth in well production. The illustrative horizon is a planning label, not a validated future operating schedule.