Tight Gas Pore Volume from Squared-Pressure Decline Calculator
Enter the required inputs, confirm the units, and run the calculator to solve PV. Review the formula source and assumptions before using the result in engineering work.
Calculation context and source notes
Tight Gas Pore Volume from Squared-Pressure Decline calculates pore volume for unconventional reservoirs workflows in reservoir engineering. The page keeps the declared variables, units, source relationship, and output definition visible for technical review.
Use this formula when the listed inputs (T, mu_g_avg, z_avg, q_i, mu_gi, c_ti, P_i, P_wf, D_i) are known and the assumptions behind the cited unconventional reservoirs relationship match the engineering case being checked.
Solves for
PV (reservoir volume units)
Best next page
Formula, variables, and sourceFormula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns PV = 29,212,333.333333 reservoir volume units. Defaults demonstrate the implementation; they are not recommended field values.
620
0.02
0.9
500
0.018
0.00001
4000
1000
0.002
Input definitions
T
degRReservoir Temperature
mu_g_avg
cPAverage Gas Viscosity
z_avg
dimensionlessAverage Gas Compressibility Factor
q_i
MSCF/dayInitial Gas Rate
mu_gi
cPInitial Gas Viscosity
c_ti
1/psiInitial Total Compressibility
P_i
psiInitial Reservoir Pressure
P_wf
psiBottom-Hole Flowing Pressure
D_i
1/dayInitial Decline Rate
Output definitions
PV
Pore Volume
q_i
Initial Gas Rate
D_i
Initial Decline Rate
Engineering use, assumptions, and limits
Use this formula when the listed inputs (T, mu_g_avg, z_avg, q_i, mu_gi, c_ti, P_i, P_wf, D_i) are known and the assumptions behind the cited unconventional reservoirs 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.
Frequently asked questions
What inputs does the Tight Gas Pore Volume from Squared-Pressure Decline calculator need?
The calculation uses Reservoir Temperature (T), Average Gas Viscosity (mu_g_avg), Average Gas Compressibility Factor (z_avg), Initial Gas Rate (q_i), Initial Gas Viscosity (mu_gi), Initial Total Compressibility (c_ti), Initial Reservoir Pressure (P_i), Bottom-Hole Flowing Pressure (P_wf), Initial Decline Rate (D_i). Enter values on the units shown beside each field.
What result does this calculator return?
The primary result is pore volume in reservoir volume units. The formula section shows the declared relationship, variables, and a reproducible default calculation.
What should I check before using the result?
Confirm the unit basis, source applicability, and input quality. The calculation does not replace a full engineering model or operating procedure. Mixing unit systems without converting the inputs.
Source and record status
Source metadata identifies the relationship implemented by the calculator. Check the cited edition, unit basis, and scope against the engineering case before operational use.
Advanced Reservoir Engineering, Ahmed, T., McKinney, P. D. (2005)
Ahmed, T. and McKinney, P. D. 2005. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 3, Page 252.
Open source reference