[B][COLOR=red]what is the differance between Differential sticking and Mechanical [/COLOR][COLOR=red]?stucking[/COLOR][/B]
Differential sticking one of the most common problem occure during drilling as aresult of differential pressure between hydrostatic pressure of mud and formation pressure of mud ie when the hydrostatic pressure is greater than the formation pressure which cause pushing adrill string into afilter cake of permeable formation
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when the Differential sticking occure moving the pipe string
in the upward and downward direction is impossible
but
free circulation is easily established
What should i do for this situation ?
Reducing of hydrostatic pressure by circulation and reducing mud weight
Reducing the contact area by reducing the thickness of filter cake by using the solids in mud to the minimum and use mud of low water loss
Most pipe sticking problems are associated with drill collars and the ideal solution is to use drill collars with minimum surface area by using [COLOR=blue]aspirally grooved drill collar[/COLOR] and [COLOR=blue]heavy weight drill pipe[/COLOR]
The contact area can also be reduced by using [COLOR=blue]stabiliser[/COLOR] which centralise the drill collars within the hole
Displacing the choke
Maintain drill string rotation at all times if possible
Dont use high mud weight
to free mechanical stucking we should be
rotating and reciprocating the drill string and increase flow rate
or
increasing the mud weight if mechanical stucking caused as arusult of plastic shale
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Mechanical stuck pipe
When drill cutting or sloughing formation pack off the annular
space around the drill string as aresult of improper cleaning
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The settling of alarge amount of suspended cutting to the bottom when the pump is shut down
When drill string is run too fast it hits abridge or tight spot
[CENTER]Tight spots can result from drilling undersized holes due to the use
of worn drill bits
Drilling at excessive Rates Of Penetration (ROP) for a given circulation rate. This generates cuttings faster than they can be circulated mechanically from the annulus
The usual method used to free mechanical stuck pipe is to work the drill string either by rotation and pulling it or by activating adrilling jar
[B]note[/B]
[B]Differential sticking there is acirculation but there is no a rotation [/B]
[B] Mechanical sticking there is no acirculation and arotation[/B]
source of this article from
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