Drilling EngineeringMud and Cementing
API Water Loss from Seven-and-a-Half Minute Filtrate Formula
API Water Loss from Seven-and-a-Half Minute Filtrate calculates api water loss at 30 minutes for mud and cementing workflows in drilling engineering.
How engineers use this formula
Use this formula when the listed inputs (V_a, V_sp) are known and the assumptions behind the cited mud and cementing 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_30 equals 30 cm^3.
V_acm^3
16
V_spcm^3
2
Inputs
V_a
cm^3Water loss in 7.5 minutes
V_sp
cm^3Spurt loss
Outputs
V_30
cm^3
API water loss at 30 minutes
V_a
cm^3
Water loss in 7.5 minutes
V_sp
cm^3
Spurt loss
Source and review
reviewed501 Solved Problems and Calculations for Drilling Operations, Robello, S.E. (2015)
Samuel, E. Robello. 501 Solved Problems and Calculations for Drilling Operations, Sigma Quadrant, Houston, Texas, 2015, Page 199.
Source