You previously learn about hydrostatic pressure lose due to pulling out of hole . This article will use the same concept but we will determine how many feet of drill pipe pulled to lose certain amount of hydrostatic pressure in well bore.

**Oilfield Unit**

Pipe pulled, ft = (hydrostatic pressure loss in psi × (casing cap in bbl/ft – pipe displacement in bbl/ft)) ÷ (mud weight in ppg × 0.052 × pipe displacement in bbl/ft)

**Example: **Determine the FEET of drill pipe that must be pulled to lose 200 psi overbalance using the following data:

Hydrostatic pressure loss = 200 psi

Casing capacity = 0.0873 bbl/ft

Pipe displacement = 0.01876 bbl/ft

Mud weight = 12.0 ppg

Pipe pulled = 200 psi × (0.0873 – 0.01876) ÷ (12.0 ppg × 0.052 × 0.01876)

Pipe pulled = 1171 ft

You need to pull 1171 ft of dry pipe to lose 200 psi hydrostatic pressure.

**Metric Unit**

Pipe pulled, m = (hydrostatic pressure loss in KPa× (casing cap in m^{3}/m- pipe displacement in m^{3}/m-)) ÷ (mud weight in kg/m^{3}× 0.00981× pipe displacement in m^{3}/m)

**Example: **Determine how many meters of drill pipe that must be pulled to lose 1400 KPa overbalance using the following data:

Hydrostatic pressure loss = 1400 KPa

Casing capacity = 0.04554 m^{3}/m

Pipe displacement = 0.00979 m^{3}/m

Mud weight = 1440 kg/m^{3}

Pipe pulled = 1400× (0.04554 – 0.00979 ) ÷ (1440 × 0.00981 × 0.00979 )

Pipe pulled = 362 m

You need to pull 362 m of dry pipe to lose 1400 KPa hydrostatic pressure.

**Please find the Excel Spreadsheet to calculate **how many feet or meter of drill pipe pulled to lose certain amount of hydrostatic pressure in well bore.

**Ref books:**

Lapeyrouse, N.J., 2002. Formulas and calculations for drilling, production and workover, Boston: Gulf Professional publishing.

Bourgoyne, A.J.T., Chenevert , M.E. & Millheim, K.K., 1986. SPE Textbook Series, Volume 2: Applied Drilling Engineering, Society of Petroleum Engineers.

Mitchell, R.F., Miska, S. & Aadny, B.S., 2011. Fundamentals of drilling engineering, Richardson, TX: Society of Petroleum Engineers.