Gas-Oil Ratio Calculator

Producing GOR is a direct measurement — gas production divided by oil production, in scf/bbl — reflecting exactly what's coming out of the wellhead right now. Solution GOR is a theoretical estimate from Standing's correlation of how much gas the oil could hold dissolved in solution at the current reservoir pressure and temperature. They can diverge significantly, especially below the bubble point where free gas has already come out of solution and the producing GOR climbs above the solution GOR.

The calculator buckets GOR into five standard reservoir-engineering categories — heavy oil below 200 scf/bbl, black oil from 200–3,000, volatile oil from 3,000–15,000, gas condensate from 15,000–100,000, and dry gas above that — because GOR is a widely used first-pass indicator of what kind of hydrocarbon system you're dealing with. It's a simple, single-variable classification, so a reservoir near a boundary or with unusual fluid properties should be confirmed with full PVT analysis rather than relying on GOR alone.

Standing's correlation for solution GOR requires a gas specific gravity term, but since gas composition isn't collected as an input to this calculator, it substitutes a typical value of 0.7 for associated gas. If your actual produced gas is notably richer or leaner than that, the solution GOR and formation volume factor outputs will be less accurate — a real PVT report with your measured gas gravity would refine both.

The calculator flags 'above bubble point' whenever your entered reservoir pressure exceeds the bubble point pressure you supplied, meaning the reservoir fluid is still undersaturated — all the gas remains dissolved in the oil and no free gas phase has formed yet. Once reservoir pressure drops below the bubble point during production, gas begins breaking out of solution, which is typically when producing GOR starts rising above the solution GOR.