Lost Circulation

Kicks can occur when total lost circulation occurs.

If the loss of whole mud to natural or artificially induced fractures is sufficiently great, then all returns from the well will cease and the level of mud in the well annulus will drop.

Loss of circulation can occur to cavernous or vugular formations; naturally fractured, pressure depleted or sub-normally pressured zones; fractures induced by excessive pipe running speeds; annulus plugging due to BHA balling or sloughing shales; excessively high annular friction losses; or excessive circulation breaking pressures when mud gel strength is high. In the North Sea lost circulation due to induced pressure surges is more commonly a cause of partial loss of returns.

When this type of kick occurs, it may rapidly become very severe since a large influx can occur before a rising annulus mud level is seen, for this reason, it is recommended that the annulus should be filled with water to maintain the best possible hydrostatic head in the well.

In many cases the mud level only drops a few hundred feet, and the addition of water reduces the underbalance in the well to a minimum. If flow still occurs, it does so at a reduced rate, allowing more time for emergency measures, or well healing procedures, to be carried out.

A note should be kept of the volume of water pumped, to enable an estimate of the maximum pressure the well can take.

CONTROLLED SITUATION

POTENTIAL KICK SITUATION

Drop in Mud Level Reduces

Hydrostatic Pressure On Gas Zone

Hydrostatic Pressure On Gas Zone

Mud Losses

Lost Circulation Formation

Mud Losses

Lost Circulation Formation

Mud Losses

Figure 5 - Typical Situations

Lost Circulation Mud
Figure 6 - Lost Circulation

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Responses

  • iivari
    How lost circulation occure ?
    9 years ago
  • frank
    How to kill well with mud losses?
    9 years ago
  • john
    Does a kick occur in event of total lost in circulation?
    2 years ago

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