Gas wells are often described by a single benchmark number that stands for their raw deliverability: the absolute open flow potential. It represents what a well could theoretically flow if you could pull its flowing pressure all the way to zero. This guide defines AOF, explains how gas-well deliverability tests - the backpressure C-and-n method and the isochronal test - establish it, and describes why regulators and reserves teams so often cite absolute open flow potential as a headline measure of a gas well.
Absolute Open Flow Potential (AOF) in one line: Absolute open flow potential, or AOF, sometimes written AOFP, is the theoretical maximum rate a gas well could produce if its flowing bottomhole pressure were reduced to zero, or in some conventions to atmospheric pressure. It is not a rate the well is actually produced at but a benchmark of deliverability determined from a deliverability test. AOF is widely used by regulators and reserves teams as a standard measure of a gas well's productive capacity.
AOF answers a hypothetical question: if a gas well were opened up so completely that the flowing pressure at the bottom of the hole fell to zero, how much gas would it deliver? Nobody actually produces a well that way - flowing pressure is always some finite value set by the tubing, choke, and surface facilities - but the zero-pressure rate serves as a clean, single-number index of the well's raw capacity. Because it is defined at a fixed, extreme condition, AOF lets very different wells be compared on the same footing.
The value has to be extrapolated rather than measured directly, since you cannot literally run a well at zero flowing pressure. Deliverability testing measures the well's rate at several finite drawdowns, fits a relationship between rate and pressure, and extends that relationship to the zero-flowing-pressure condition to obtain the AOF. This extrapolation is why AOF is described as a theoretical or potential rate: it is the endpoint of a fitted deliverability curve, not an observed flow.
It is important to keep AOF distinct from the rate a well is actually allowed or intended to produce. Operating a well near its open flow potential would usually be damaging or impractical, and regulators historically limited production to a fraction of open flow rather than the full value. AOF is best understood as a capacity benchmark and a regulatory reference point, not a target rate - a way to characterize how strong a gas well is, from which sensible operating and allocation decisions can be made.
The traditional way to establish AOF is the backpressure, or flow-after-flow, deliverability test, in which the well is produced at several stabilized rates against different surface backpressures and the rate and flowing pressure are recorded at each. These data are fit to the classic gas deliverability equation, often written in the C-and-n form, where rate is related to the difference between the squares of reservoir and flowing pressures through a performance coefficient C and an exponent n. Once C and n are known, setting the flowing pressure to zero in the equation gives the AOF.
The exponent n and coefficient C carry meaning of their own. The exponent n reflects the flow regime and typically falls between one half and one, with values near one indicating laminar-dominated flow and lower values indicating stronger turbulent, non-Darcy effects near the wellbore. The coefficient C bundles the reservoir and fluid properties that set the overall level of deliverability. Together they define the deliverability curve, and extrapolating that curve to zero flowing pressure yields the open flow potential.
The flow-after-flow test assumes each rate stabilizes, which is impractical in low-permeability reservoirs that take a very long time to reach stable flow. For those wells the isochronal and modified isochronal tests were developed: they flow the well for equal, fixed time periods rather than to full stabilization, with pressure buildups between, and use a single extended stabilized point to fix the deliverability curve. These methods obtain a valid AOF from tight gas wells without waiting impractically long for stabilization at every rate, which is why they became standard for such reservoirs.
AOF became a standard citation because it condenses a gas well's deliverability into one comparable number that regulators, operators, and reserves teams can all reference. Regulatory bodies historically used deliverability tests and open flow potential to set production allowables - the maximum a well was permitted to produce - often as a fraction of AOF, to prevent over-production and reservoir damage while allocating market demand across wells. Even where allowables have relaxed, the AOF remains a recognized way to report and compare well capacity in regulatory filings.
For reserves and asset teams, AOF is a useful high-level indicator of how strong a well is and how it stacks up against offsets, feeding into deliverability planning and the sizing of gathering and compression. It is not a substitute for a full nodal analysis or a reserves forecast, but as a single deliverability index it helps rank wells and screen opportunities quickly. Because it is defined at a fixed condition and derived by a standardized test, it travels well between engineers and organizations.
Whichever test establishes an AOF, its credibility rests on accurate flow rates and pressures during the test, and on knowing how conditions held over the test's duration. A cloud SCADA platform such as Merobix records the flowing pressures and gas rates from field instrumentation over protocols such as Modbus and DNP3 with full history, which supports both the conduct of a deliverability test and the later check of whether a well's actual behavior still matches the deliverability curve behind its AOF. As reservoir pressure declines over time, a well's open flow potential falls, and continuous pressure and rate history is what lets an operator see when a previously quoted AOF no longer reflects the well.
No. AOF is a theoretical benchmark - the rate a well would deliver if flowing bottomhole pressure were reduced to zero - not a rate the well is produced at. Real wells always flow against some finite pressure set by tubing, chokes, and facilities, and producing near open flow would usually be damaging or impractical. AOF is used as a capacity benchmark and regulatory reference, not a target rate.
A flow-after-flow, or backpressure, test produces the well at several stabilized rates against different backpressures, which requires each rate to reach stable flow. In low-permeability wells that stabilize very slowly, isochronal and modified isochronal tests are used instead: they flow the well for equal fixed periods with buildups between and use one extended stabilized point to fix the deliverability curve, avoiding impractically long stabilization at every rate.
The C-and-n equation is the classic gas deliverability relationship, in which flow rate is related to the difference between the squares of reservoir and flowing pressures through a coefficient C and an exponent n. The exponent n reflects the flow regime, typically between one half and one, and C bundles reservoir and fluid properties. Fitting C and n to test data and setting flowing pressure to zero gives the absolute open flow potential.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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