Oil in place is the total quantity of crude oil that is originally found in a subsurface reservoir. It encompasses all the oil contained in the rock formations within a specific reservoir, regardless of whether it can be technically or economically recovered.
Saturated oil reservoir is one where the oil is at its bubble point pressure. At this pressure, the oil contains the maximum amount of dissolved gas that it can hold under the given temperature conditions. Any reduction in pressure (during production) will cause gas to start coming out of solution, forming a separate gas phase. This distinguishes it from an undersaturated oil reservoir, where the pressure is above the bubble point, and no free gas exists.
Oil in Place in Saturated Oil Reservoirs Formula |
||
| \( N \;=\; \dfrac{ N_p \cdot B_o + ( G_p - N_p \cdot R_s ) \cdot B_g }{ B_o - B_{oi} + ( R_{si} - R_s ) \cdot B_g }\) | ||
| Symbol | English | Metric |
| \( N \) = Oil in Place | \(bbl\) | - |
| \( N_p \) = Cumulative Oil Production | \(STB\) | - |
| \( B_o \) = Oil Formation Volume Factor | \(bbl\;/\;STB\) | - |
| \( G_p \) = Cumulative Gas Production | \(MSCF\) | - |
| \( R_s \) = Gas Solubility | \(SCF\;/\;STB\) | - |
| \( B_g \) = Gas Formation Volume Factor | \(bbl\;/\;SCF\) | - |
| \( B_{oi} \) = Initial Oil Formation Volume Factor | \(bbl\;/\;STB\) | - |
| \( R_{si} \) = Initial Gas Solubility | \(SCF\;/\;STB\) | - |
