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Well Control Problems & Solution While Operations

Always Be Prepared for Complications & Problems During Well Control Operations

Note:

If a problem develops while killing a well, “NOTE and RECORD” the drill pipe and casing pressure, stop the pump, shut in the well, and then, evaluate the situation.

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Well controlling pressure is provided by using the horsepower of the mud pumps and the backpressure associated with the control choke manifold during Well kick circulation. Excessive pressures could develop should any part of the circulation path become plugged. Improper BHP may be induced on the well if any washouts of the circulation path occur or any other factors that may alter the hydraulics of the system.

Complications include:

Well Control Problems & Solution While Operations

Slow Pump Pressure Problems In Well Control

Obtaining Slow Pump Pressure after Kick Problems In Well Control

Well control problem: How is the slow pump pressure obtained if not recorded prior to taking a kick?

Example:

SIDPP= 500 psi

SICP = 800 psi

Slow Pump Pressure = 1000 psi

Slow Pump Rate = 30  spm

Step No. 1

  • Bring Well on Choke Using Correct Start-up Procedure

Step No. 2

  • When Both the drillpipe and Casing Pressure Gauges Have Stabilized, Read and Record the Correct Initial Circulating Pressure From the drillpipe gauge.

Step No. 3

  • From the Well Control Kill Sheet

Initial Circulating Pressure (ICP) = 1500

ICP = Slow Pump Pressure + SIDPP

1500 = ? + 500

SPP = ICP – SIDPP

1000 = 1500 – 500 psi

Float In Drill String

Well control problem: How would the SIDPP and the Slow Pump Pressure be obtained if a non-ported float is in the string and Slow Pump Pressure was not recorded prior to taking a kick?

Example:

SIDPP  = 500 psi SICP =   800 psi Slow Pump Pressure           = 1000 psi

Slow Pump Rate                 =   30 spm

Step No. 1

  • Perform a Leak off test on the float. Use the cementing pump and pump at a low rate into the drill pipe. When the float opens there will be a slight fluctuation or delay in the drill pipe pressure.

THIS IS THE SHUT-IN DRILL PIPE PRESSURE.

Step No. 2

  • Bring well on choke using correct start up procedure.
  • Obtain slow circulating rate pressure using procedure outlined on previous page.

SPP = ICP – SIDPP

1000 = 1500 – 500

Partial Lost circulation

Well Control Problem: Partial Lost Circulation while Killing Well. The most common identifications for such problems are as follows:

  • Usually indicated by non-responsive choke.
  • Gradual decrease in casing pressure followed by decrease in drill pipe pressure.
  • Decrease in mud pit volume may be observed.

Remedial Action:

  • Reduced pump rate using correct procedure, continue killing well with wait and weight method or driller’s method as long as mud volumes permit.
  • Remove any excess pressures being used as overbalance safety factors.
  • Use exact kill weight mud – no safety factors.
  • When mud volume becomes too low, – shut-in well – let well HEAL while building mud volume.
  • Emergency procedures to prevent the loss of control involve the use of barite and cement plugs.

Choke Problems In Well Control

Identifying and Detecting

  • Abrasive particles at high velocity  – Choke washout
  • Slouching or heaving shale – plugged choke.

NOTE: Choke problems will affect BOTH casing pressure and drill pipe pressure

Washed Out Choke Problems In Well Control

  • Gradual decrease in casing pressure followed by gradual decrease in drillpipe pressure.
  • Closing choke with little or no response to both gauges.
  • Could result in underbalance situation with additional pit volume increase if proper drill pipe pressure cannot be maintained.

Plugged Choke

  • Gradually increasing or drastically increasing casing and drill pipe pressure.
  • Opening choke with little or no response to both gauges.
  • Particles often create noise and vibration.
  • Could result in partial or complete loss of circulation.

Remedial Action

  • Stop pump and shut-in well as quickly and as safely as possible.
  • Isolated plugged choke. (Close up stream and down stream valves.)
  • If another choke is available, line up proper valves in choke manifold and resume killing well.
  • If no other choke can be used, repair plugged choke then resume kill operations.

Washed-Out Drillstring Problems In Well Control

Identifying and Detecting

  • The gradual decrease in drill pipe pressure with little or no change in casing pressure.
  • Choke closed to compensate for the loss in drill pipe pressure resulting in increased casing pressure
  • May not be noticed until:
    • Casing pressure gets so high it finally gets your attention.
    • Begin to lose partial returns
    • Increasing mud weight returns at flowline before expected.
  • Drastic decrease in drill pipe pressure with little or no change in casing pressure

Remedial Action

  • Determine depth of washout.
  • If KWM is above washout in annulus, continue kill procedures.
    • Stop pump and shut-in well.  Bring well on choke to determine new circulating pressure.

Shallow Washout

  • Stop pumping – implement Volumetric method procedure.
  • Pump softline or other plugging material.
  • Coiled tubing/small tubing with packer.
  • Perform stripping operations out of hole to remove washout joint(s)

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