Swabbing And Surging

Swabbing is when bottom hole pressure is reduced below formation pressure due to the effects of pulling the drill string, which allows an influx of formation fluids into the wellbore.

When pulling the string there will always be some variation to bottom hole pressure. A pressure loss is caused by friction, the friction between the mud and the drill string being pulled. Swabbing can also be caused by the full gauge down hole tools (bits, stabilisers, reamers, core barrels, etc.) being balled up. This can create a piston like effect when they are pulled through mud. This type of swabbing can have drastic effects on bottom hole pressure.


The factors affecting swabbing and surging are:

  • Pulling speed of pipe.
  • Mud properties.
  • Viscosity.
  • Hole geometry. Surging

Surging is when the bottom hole pressure is increased due to the effects of running the drill string too fast in the hole. Down hole mud losses may occur if care is not taken and fracture pressure is exceeded while RIH. Proper monitoring of the displacement volume with the trip tank is required at all times.

Figure 2.6



Swabbing is a recognised hazard whether it is "low" volume swabbing or "high" volume swabbing. A small influx volume may be swabbed into the open hole section. The net decrease in hydrostatics due to this low density fluid will also be small. If the influx fluid is gas it can of course migrate and expand. The expansion may occur when there is little or no pipe left in the hole. The consequences of running pipe into the hole and into swabbed gas must also be considered.

Pulling Speeds

Tripping speeds must be controlled to reduce the possibility of swabbing. It is normal practice for the Mud Logger to run a swab and surge programme and to make this information available to the Driller. This will provide ample information to reduce the possibility of unforeseen influx occurring.


Mud Properties

Controlling the rheology of mud is important. Controlling water-loss to avoid thick wall cake will also help.

Trip Margin

A safety factor to provide an overbalance to compensate for swab pressure can be: Trip Margin Factor APL psi

APL = Annulus Pressure Loss

If swabbing has been detected and the well is not flowing a non return valve should be installed and the bit returned to bottom. Flow check each stand. Once back on bottom the well should be circulated and the bottoms up sample checked for contamination.

If the well is flowing or the returns from the well are excessive when tripping in then the following should be carried out:

  • Install a non return valve. If there is a strong flow then a kelly cock may have to be installed first.
  • Shut the well in.
  • Prepare for stripping.
  • Strip in to bottom.
  • Circulate the well, check bottoms up for contamination.

Continuous monitoring of replacement and displacement volumes is essential when performing tripping. A short wiper trip and circulating the well before pulling completely out of the hole will provide useful information about swabbing and pulling speeds.

Useful formulae for calculating the psi reduction per foot of drill pipe pulled are as follows:

Pulling Dry Pipe: psi/ft or dry pipe pulled = '

  • casing cap. (bbls/ft) - metal disp. (bbls/ft))
  • mud grad. (psi/ft) x metal disp. (bbls/ft)) \ (casing cap. (bbls/ft) - metal disp. (bbls/ft)) /
  • mud grad. (psi/ft) x metal disp. + cap. (bbls/ft) \ -------I
  • casing cap. (bbls/ft) - metal disp. + cap. (bbls/ft))/


Was this article helpful?

+12 -2
Serious MLM Mistakes

Serious MLM Mistakes

Discover the Pitfalls and Traps in Network Marketing that You Can Avoid Saving You TONS of Time, Money amp Mistakes. to the exciting follow-up book on Network Marketing. In the first book, we have explored on one of the most important yet least talked about, most overlooked aspect of network marketing or Multi-level Marketing MLM.

Get My Free Ebook


  • Karita
    What is surging in drilling?
    3 years ago
  • michael
    What is swabbing and surging?
    3 years ago
  • Kari Penttinen
    What is surging effect in well?
    3 years ago
  • jamie
    Does swabbing has any effect on annulus pressure?
    3 years ago
  • gloriana
    What is surging in drill?
    3 years ago
  • j
    How to resolve kick due to swabbing?
    3 years ago
    What is surge and swab in enginner oil?
    3 years ago
  • Sophia
    What is swabbing operations?
    2 years ago
  • hana
    What is surge and swabbing?
    2 years ago
  • dennis
    Is it unusual to get alot of sand and gristle wen swabbing gas well?
    1 year ago
    Why is swab less in the casing vs open hole?
    1 year ago
  • calum
    What is well drilling trip or strip?
    1 year ago
  • vesa
    What happens to swabbing fluids from an oil well?
    1 year ago
  • duenna
    1 year ago
  • Klaus
    What detects swabbing and surging?
    1 year ago
  • celso
    1 year ago
  • Aulis
    What is swab effect in drilling operations?
    1 year ago
  • Shannon
    What is swabbing in drilling operations?
    1 year ago
  • eino tuukkanen
    What is surge consideration in drilling?
    11 months ago
  • jessica
    What increase chances of swabbing in making oil?
    11 months ago
  • anke nagel
    Which factor may cause swabbing in drilling?
    10 months ago
  • Alfredo Genovese
    Can swabbing cause oil well coning?
    10 months ago
  • Sven
    What is the swabing while pull out pf hole?
    9 months ago
  • Ines Endrizzi
    Why circulate bottoms up before tripping?
    6 months ago
  • Ronan
    How long should you swab a well?
    5 months ago
  • Eerik
    Is there a method to swab oil well casing with tubing in well?
    5 months ago
  • Ella
    What is surging and swabing?
    4 months ago
  • Settimo
    What is surge effect when running in casing?
    4 months ago
  • ilse
    How do swab cups work in an oilwell?
    4 months ago
  • Kaija
    What is the purpose of the control of well?
    2 months ago
  • dawit
    Does a well have to be dead to swab?
    22 days ago

Post a comment