Heat Remaining in Reservoir - Marx and Langenheim Formula
Heat Remaining in Reservoir - Marx and Langenheim calculates heat remaining in reservoir for waterflooding and eor workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (Q_i, M_r, h, G, alpha_s, M_s) are known and the assumptions behind the cited waterflooding and eor 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, Q equals 299,072,265.625 BTU.
1000000
35
50
0.5
0.8
40
Inputs
Q_i
BTUTotal heat injected
M_r
BTU/ft^3-FVolumetric heat capacity of reservoir
h
ftHeated reservoir thickness
G
dimensionlessDimensionless time constant
alpha_s
ft^2/daySteam diffusivity
M_s
BTU/ft^3-FVolumetric heat capacity of formations adjacent to heated zone
Outputs
Q
Heat remaining in reservoir
Q_i
Total heat injected
M_r
Volumetric heat capacity of reservoir
h
Heated reservoir thickness
G
Dimensionless time constant
alpha_s
Steam diffusivity
M_s
Volumetric heat capacity of formations adjacent to heated zone
Source and review
reviewedThermal Recovery, Prats, M. (1986)
Prats, M. 1986. Thermal Recovery. Society of Petroleum Engineers, New York, Chapter 5, Page 44.
Source