Free Point Formula |
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\( L \;=\; \dfrac{ E \cdot S \cdot A_c }{ P \cdot 12 }\) (Free Point) \( E \;=\; \dfrac{ L \cdot P \cdot 12 }{ S \cdot A_c }\) \( S \;=\; \dfrac{ L \cdot P \cdot 12 }{ E \cdot A_c }\) \( A_c \;=\; \dfrac{ L \cdot P \cdot 12 }{ E \cdot S }\) \( P \;=\; \dfrac{ E \cdot S \cdot A_c }{ L \cdot 12 }\) |
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| Symbol | English | Metric |
| \( L \) = Length of Free Pipe | \(ft\) | - |
| \( E \) = Modulus of Elasticity of Steel (psi) | \(lbf\;/\;in^2\) | - |
| \( S \) = Stretch in Drill Pipe (Elongation) | \(in\) | - |
| \( A_c \) = Pipe Wall Area Cross-section | \(in^2\) | - |
| \( P \) = Overpull Difference Metween Max. and Min. Pull of Pipe | \(lbf\) | - |
Free point is the location in the wellbore where the drillstring is not stuck and can move freely. Determining the free point is crucial when a portion of the drillstring becomes stuck, as it helps in planning the recovery and freeing operations. In other words, it is the highest point above which the pipe is not stuck and can move freely. Determining the free point is crucial when a section of the pipe becomes stuck, as it allows operators to identify the precise location where the pipe can still be manipulated and where it is immobilized.
Determining the free point is a critical step in managing stuck pipe incidents in drilling operations. It enables operators to localize the problem and apply appropriate techniques to recover the drillstring efficiently and safely. By using tools like the free point indicator and measuring stretch and torque, operators can accurately identify the free point and minimize downtime and operational risks.
Importance of Determining the Free Point
Stuck Pipe Recovery - Identifying the free point allows operators to understand where the drillstring is free and where it is stuck, which is essential for deploying tools and techniques to free the stuck section.
Minimize Damage - Accurate determination of the free point helps in avoiding unnecessary force on the free sections of the drillstring, minimizing the risk of additional damage or breaking the string.
Operational Efficiency - Knowing the exact location of the stuck point can significantly reduce non-productive time (NPT) by streamlining the recovery operations.
