kick_prevention

7/30/2019 Kick_Prevention

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Kick Prevention

n Primary Well Control.

n Tripping Practices.



Kick Prevention

At the end of this section you should be able to:

n Describe primary well control and practices to prevent a kick.



Kick PreventionKick Prevention

Maintenance of primary well control is the foundation of kick prevention, which isensured by the use of a drilling or completion fluid of sufficient density to overbalancethe highest exposed formation pressure.

Primary Well Control:Primary Well Control:

The hydrostatic pressure acting against a formation primarily comes from the weight of the drilling fluid used. A drilling fluid density that will maintain a minimum overbalance of 200 psi, or 50 psi with the marine riser removed (operations with subsea BOPs) isrecommended. It is of the utmost importance to ensure that primary well control ismaintained at all times. This involves the following:

– Drilling fluids of adequate density are used.

– Well is kept full of adequate density fluid at all times. – Determining a maximum tripping speed based on swab / surge calculations.

– Active volumes are continuously monitored, especially during tripping.

– Changes in density, volumes and flow rate of drilling fluids from the wellbore areimmediately detected and appropriate action taken.




Tripping Practices:Tripping Practices:Statistics show that the majority of kicks are taken while pulling the drill string from thewellbore. This is a problem that can be avoided if the crew is well trained and if proper procedures are followed.

During tripping, the potential exists for a significant reduction in bottomhole pressure dueto the following effects:

– Swabbing during trips. – Not adequately filling the hole during a trip. – Insufficient drilling fluid density (remove of ECD).

The following guidelines are the preparations for a trip:

– Check hole conditions.

– Flow checks. – Slugs. – Mud bucket. – Trip tank – Trip sheet.

– Filling drill pipe.

– Proper hole file. – Tripping speed. – Breaking circulation. – Trip interruptions. – Save valve.




n Check Hole Conditions.

Before starting tripping out of the hole with drill pipe, the drilling fluid shall be in goodcondition: no indication of lost circulation, no indication of influx of formation fluidspresent prior to pulling pipe, the drilling fluid density in and out will not differ morethan 0.2 ppg.

n Flow checks.

A flow check is the observation of the well without circulation. Flow checks are madeto determine if the well is, or is not flowing. A flow check will not prevent a kick, it willindicate whether the well is stable or not.

n Slugs.

When possible, and after a flow check has confirmed that the well is static, a slug willbe prepared and displaced in the drill string prior to POOH

n Mud Bucket.Should be readied if a slug cannot be pumped or if pipe must be pulled wet. Designshould be arranged so that returns from the mud bucket drain to the trip tank.




n Trip Tank. A trip tank is a low-volume, (100 barrels or less), calibrated tank that can be isolatedfrom the remainder of the surface drilling fluid system and must be used to keeptrack of fluid volumes while both tripping in and tripping out of the hole, making surethat the borehole is kept full at all times.

n Trip Sheet.

In conjunction with the trip tank, a trip sheet must always be used while tripping inand out of the hole.

n Fill ing Drill Pipe.

With a solid float in the string, drill pipe will need to be manually filled at surface at amaximum of every 10 to 15 stands while RIH. With the BHA in open hole,reciprocating is recommended while filling the pipe to avoid sticking problems.

n Proper Hole Fill.If the hole is not taking the proper amount of fluid, it is important to stop tripping andflow check. The pipe should be returned to bottom, another flow check performedand a minimum of one bottom’s up should be circulated.




n Tripping Speed (Swabbing / Surging).Pipe shall not be pulled faster than the speed that would cause excessive swabbing.Similarly, pipe shall not be run in the hole faster that the speed that will generatesurge pressures that can cause formation breakdown leading to losses.

Swab and surge calculations should be performed for each trip in and out of thehole.

n Breaking Circulation.To reduce possibilities of high surge pressures, break circulation whenever necessary (prior to and after entering open hole).

n Trip Interruptions.

Any time a trip is interrupted, the installation of a Full Opening Safety Valve isrequired.

n Safety Valve.

Suitable safety valves with appropriate connections of crossover subs to fit all drillpipe and BHA connections must be on the rig floor, in the 'open' position ready for use with proper fittings and handling devices.

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