Radius of Investigation Calculator
Enter the required inputs, confirm the units, and run the calculator to solve r_i. Review the formula source and assumptions before using the result in engineering work.
Calculation context and source notes
Radius of Investigation calculates radius of investigation for pressure transient analysis 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 (k, t, phi, mu, c_t) are known and the assumptions behind the cited pressure transient analysis relationship match the engineering case being checked.
Solves for
r_i (ft)
Best next page
Formula, variables, and sourceFormula, variables, and default calculation
Reproducible default result
With the default values shown below, the calculation returns r_i = 846.171115 ft. Defaults demonstrate the implementation; they are not recommended field values.
50
24
0.18
1.2
0.00001
Input definitions
k
mDPermeability
t
hElapsed Investigation Time
phi
fractionPorosity
mu
cPFluid Viscosity
c_t
1/psiTotal Compressibility
Output definitions
r_i
Radius of Investigation
k
Permeability
t
Elapsed Investigation Time
phi
Porosity
mu
Fluid Viscosity
c_t
Total Compressibility
Engineering use, assumptions, and limits
Use this formula when the listed inputs (k, t, phi, mu, c_t) are known and the assumptions behind the cited pressure transient analysis 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 Radius of Investigation calculator need?
The calculation uses Permeability (k), Elapsed Investigation Time (t), Porosity (phi), Fluid Viscosity (mu), Total Compressibility (c_t). Enter values on the units shown beside each field.
What result does this calculator return?
The primary result is radius of investigation in ft. 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.
Ahmed, T. and McKinney, P. D. Advanced Reservoir Engineering, Gulf Publishing of Elsevier, Chapter 1, Page 134.
Open source reference