Reservoir EngineeringMaterial Balance
Rock Expansion Term in Abnormally Pressured Gas Reservoirs Formula
Rock Expansion Term in Abnormally Pressured Gas Reservoirs calculates rock expansion term for material balance workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (c_f, c_w, S_wi) are known and the assumptions behind the cited material balance 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, E_R equals 0.000006 1/psi.
c_f1/psi
0.000004
c_w1/psi
0.000003
S_wifraction
0.25
Inputs
c_f
1/psiFormation Compressibility
c_w
1/psiWater Compressibility
S_wi
fractionInitial Water Saturation
Outputs
E_R
1/psi
Rock Expansion Term
c_f
1/psi
Formation Compressibility
c_w
1/psi
Water Compressibility
S_wi
fraction
Initial Water Saturation
Source and review
reviewedAdvanced 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 213.
Source