Gas-Oil Ratio (GOR)
Compute the gas-oil ratio (GOR) by dividing the produced gas volume by the oil volume, in scf/STB (standard cubic feet per barrel). It is a central petroleum-production parameter: it indicates how much gas accompanies the oil, characterizes the reservoir fluid type (black oil, volatile, gas-condensate) and sizes the surface separation equipment. A rising GOR can signal gas-cap breakthrough at the well. Enter the gas and oil volumes.
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Gas-oil ratio (GOR)
The gas-oil ratio (GOR) — standard cubic feet of gas per barrel of oil — ranks among the first things measured in an oil well, and it says a great deal about the fluid down below. A low GOR (<500 scf/STB) indicates 'black' oil, heavy and with little dissolved gas; as the value rises, the fluid grades into volatile oil, and a very high GOR characterizes gas-condensate or gas. GOR drives the design of surface separation (how many separator stages, compressor sizing) and the economics of the field, since gas and oil carry different values. Over the life of the well, a GOR that climbs unexpectedly works as a warning sign: it may mean the pressure has fallen below the bubble point, releasing gas that had been dissolved, or that the gas cap of the reservoir is coning toward the well — and action is needed. Enter the gas and oil volumes.
Related Tools
Oil in Place (OOIP)
Compute a reservoir's original oil in place (OOIP) by the volumetric method, OOIP = 7758·A·h·φ·(1−Sw)/Boi, in stock-tank barrels (STB). It combines the reservoir area (acres), the porous thickness (ft), the porosity (φ), the water saturation (Sw) and the oil formation volume factor (Boi). The constant 7758 converts acre-feet into barrels. It is the basis of any oil-field evaluation. Enter the area, thickness, porosity, water saturation and Boi.
Oil Formation Volume Factor (Bo)
Compute the oil formation volume factor (Bo) by dividing the volume the oil occupies at reservoir conditions by the volume it occupies at the surface (stock-tank barrels). Bo is always greater than 1 because, in the reservoir, the oil is hot and has dissolved gas, occupying more space; as it rises and loses gas and heat, it shrinks. It is essential to convert reservoir volumes into surface production. Enter the volumes at reservoir and surface conditions.
Reservoir Net Pay
Compute a reservoir's net pay (net productive thickness) by multiplying the gross interval thickness by the net-to-gross ratio (N/G), the fraction of rock with enough porosity and permeability to produce. Shale layers, tight rock or water zones are discounted. The net pay, not the total thickness, is what enters the oil and gas volume calculations. Enter the gross thickness and the net-to-gross ratio.
Reservoir Recovery Factor
Compute a reservoir's recovery factor, RF = (Np/N)·100%, the fraction of the original oil (N, or OOIP) that will actually be produced (Np). It is one of the most important — and uncertain — numbers in the industry: primary recovery (natural energy) is usually 5–15%; with secondary recovery (water/gas injection) it rises to 30–50%; and advanced methods (EOR) can go further. It defines the field's economic value. Enter the cumulative production and the original oil in place.
Back Work Ratio (BWR)
Calculate the back work ratio (BWR) of a power cycle, BWR = w_compressor ÷ w_turbine, dividing the work consumed by the compressor (or pump) by the gross work produced by the turbine. The dimensionless result shows what fraction of turbine work is reinvested to compress the fluid. In gas turbines (Brayton cycle) the BWR is high (0.4–0.6), since compressing gas is costly; in steam Rankine cycles it is tiny (~0.01), since pumping liquid is cheap. A high BWR makes the cycle sensitive to component efficiencies. Enter the compressor work and the turbine work.
Recoverable Oil Reserves
Compute the recoverable oil reserves by multiplying the original oil in place (OOIP) by the recovery factor (%). While the OOIP is the total volume present in the rock, only a fraction is technically and economically extractable — those are the reserves that actually have value and enter oil companies' books. It is the number behind asset valuations and investment decisions. Enter the OOIP and the recovery factor.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.