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

WELL CONTROL COURSE SECTION A

SECTION A

KEY DEFINITIONS

Drilling Ahead

WHAT IS A KICK?

IT IS AN INFLUX OF FORMATION FLUID

THAT CAUSES THE WELL TO FLOW.

 

WHAT IS A BLOWOUT?

AN UNCONTROLLED EXIT OF THE FORMATION FLUIDS

AT THE SURFACE

 Hydrostatic Pressure

Hydro- means a fluid

Static- means at rest

Hydrostatic in the wellbore is from the mud

MUD HYDROSTATIC

         VERTECAL  WELL      

STANDERED FORMULA  WITH  FT., PPG AND PSI

MUD HYDROSTATIC  HP  = 0.052 X MUD WEIGHT X DEPTH

MUD GRADIANT   =  0.052  X MUD WEIGHT           PSI\FT.

Pressure (psi) = Mud Weight x .052 x TVD

Pressure Gradient (psi/ft) = Mud Weight, ppg x .052

Pressure Gradient (psi/ft) =Pressure, psi ¸ TVD, ft

Mud Weight, ppg = Pressure Gradient ¸ .052

Mud Weight (ppg) = Pressure ¸ TVD ¸ .052

TVD (ft) = Pressure (psi) ¸ Mud Weight (ppg) ¸ 0.052

FORMATION FLUID 

Fluid present in the pore space of the rock.

FORMATION PRESSURE

 

The pressure of the formation fluids.

  What is formation fluid pressure?

Formation Pressure: is the fluid pressure in the pore spaces of the formation.

BOTTOM HOLE PRESSURE 

IT  IS THE TOTAL  PRESSURES  EXERTED AT THE  BOTTOM  OF  THE WELL.

Balance

 

Mud Hydrostatic =Formation Pressure

Overbalance

 

Mud Hydrostatic >  Formation Pressure

Underbalance

  

Mud Hydrostatic <  Formation Pressure

 

WHAT IS WELL CONTROL?

1-PREVENTING A KICK

PRIMARY

2-SHUTTING IN THE WELL AFTER A KICK HAS BEEN TAKEN

SECONDARY

  

Primary control

Secondary Control

Blowout Preventers

 

WELL CONTROL CYCLE

HOW CAN KICKS HAPPEN?

Mud Hydrostatic and Formation Pressure

Always Remember that HP and FP are two opposite forces.