Efficiency of Block and Tackle System Formula
Efficiency of Block and Tackle System calculates block and tackle efficiency for drillstring and rig mechanics workflows in drilling engineering.
How engineers use this formula
Use this formula when the listed inputs (F_h, v_t, F_f, v_f) are known and the assumptions behind the cited drillstring and rig mechanics 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_bt equals 0.909091 fraction.
400000
60
55000
480
Inputs
F_h
lbLoad Hoisted
v_t
ft/minTraveling Block Velocity
F_f
lbLoad in Fast Line
v_f
ft/minFast Line Speed
Outputs
E_bt
Block and Tackle Efficiency
F_h
Load Hoisted
v_t
Traveling Block Velocity
F_f
Load in Fast Line
v_f
Fast Line Speed
Source and review
reviewed501 Solved Problems and Calculations for Drilling Operations, Robello, S.E. (2015)
Robello, S.E. 2015. 501 Solved Problems and Calculations for Drilling Operations, Sigma Quadrant, Houston, Texas, Page 10.
Source