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