Oil in place by the volumetric method (in tonnes)
Initial oil in place by the volumetric formula of Russian and Kazakh reserves reports (GKZ): oil-bearing area, net oil pay, porosity and oil saturation, shrinkage factor and oil density. The result is in thousand tonnes and thousand cubic metres of stock-tank oil, with the dissolved gas in place.
Q = F · h · K_п · K_н · θ · ρθ = 1 / bV = F · h · K_п · K_н · θ, G = V · R_sThe tonnes come from the stock-tank oil density; the shrinkage factor θ = 1/b accounts for the oil shrinking as its gas comes out. Area and pay must belong to the same reserves category and the same zone (oil zone, water-oil zone): reserves are calculated zone by zone and added up.
Source: Guidelines for volumetric estimation of oil and gas in place (VNIGNI, 2003); Dake, Fundamentals of Reservoir Engineering (1978)
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
Within the outer oil-water contour, from the structure map; 1 km² = 1 000 × 10³ m².
Area-weighted, from the net oil pay map.
Typically 0.12–0.25 in sandstones, 0.06–0.15 in carbonates.
S_o = 1 − S_wc (connate water); usually 0.6–0.85.
From the PVT study of bottomhole samples; the shrinkage factor θ = 1/b. Usually 1.05–1.5.
1 g/cm³ = 1 t/m³; usually 0.80–0.92 (45–22 °API).
Standard m³ of gas per m³ of stock-tank oil, from the liberation test of a bottomhole sample.
Unit converter for this formulaArea · Length · Oil formation volume factor · Density and °API · Gas-oil ratio · Mass · Liquid volume · Gas volume · Fraction and percent
- m²1
- km²1·10⁻⁶
- ha0.0001
- 10³ m²0.001
- mm²1,000,000
- cm²10,000
- in²1,550
- ft²10.7639
- acre0.000247105
- V — Stock-tank oil initially in place (volume)–
- G — Dissolved gas initially in place–
More in Reserves and recovery
Stock tank volume of oil initially in place by the volumetric method, in million barrels.
Free gas initially in place by the volumetric method, in million standard cubic feet.
Gas dissolved in oil initially in place by the volumetric method, in million standard cubic feet.
The recovery factor as the product of the displacement, sweep and flooding efficiencies; the displacement efficiency comes from the initial and residual oil saturations of core floods. Recoverable reserves are that share of the oil in place.
Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.