WELL CONTROL COURSE SECTION A cont


CAUSES OF KICKS
PRIMARY CONTROL


NORMALLY:

MUD HYDROSTATIC  =    FORMATION PRESSURE


WHAT CAUSES MUD HYDROSTATIC TO DROP?


PRESSURE  =  0.052 X MUD WT X TVD

HOW CAN HYDROSTATIC PRESSURE CHANGE?








CAUSES OF KICKS (REDUCTION IN MUD WEIGHT)



RUNNING INTO A BUBBLE






CIRCULATING HOLE CLEAN


ADDITIONAL CAUSES OF KICKS (SUBSEA)


Accidental Riser Disconnect (Riser Margin)
  • Riser can be accidentally disconnected due to vessel drive off’s, hydraulic control problem, riser failure, etc.
  • Bottomhole pressure will be reduced due to net loss of hydrostatic pressure.
  • In this example, BHP would be reduced by:
Mud Loss      = 1770 x 10.8 x .052  = 994 psi
Seawater HP  = 1710 x 0.445 psi/ft  = 761 psi
Net Loss        = 994 – 761                = 233 psi

 
GAS IN THE WELLBORE




Effect Of Gas Expansion in Open Well



Gas in Subsea Riser


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