Reservoir EngineeringReservoir Volumetrics
Net Reservoir Rock Volume from Net-to-Gross Formula
Net Reservoir Rock Volume from Net-to-Gross calculates net reservoir rock volume for reservoir volumetrics workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (A, h_g, NTG) are known and the assumptions behind the cited reservoir volumetrics relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, V_nrv equals 313,632,000 ft³.
Aacres
160
h_gft
60
NTGfraction
0.75
Inputs
A
acresMapped Reservoir Area
h_g
ftAverage Gross Reservoir Thickness
NTG
fractionNet-to-Gross Thickness Ratio
Outputs
V_nrv
ft³
Net Reservoir Rock Volume
A
acres
Mapped Reservoir Area
h_g
ft
Average Gross Reservoir Thickness
NTG
fraction
Net-to-Gross Thickness Ratio
Source and review
reviewedPenn State PNG 301. Estimation of STOOIP Using the Volumetric Method, Equation 4.02 net-to-gross definition and Equation 4.03 gross rock volume.
Source