Petroleum Engineering 406

1
Petroleum Engineering 406

• Lesson 7
• Well Control
• Shallow gas and Subsea Well Control

2
Read

• Well Control Manual
• Chapter 10,15

3
Shallow Gas

• Many shallow gas sands are abnormally pressured
• Total pressure (psi) may be low high EMW
• e.g. FP 452 psi (8.7 ppg eq.) at 1000
• Drill with 9.0 ppg mud - 0.3 ppg overbalanced
  only 16 psi 35 of fluid

4
Shallow Gas

• If we shut-in on kick
• we lose circulation and possibly broach to surface

5
Shallow Gas Kicks

• Pick up Kelly until lower kelly cock clears
  rotary
• Shut down pumps
• Check for flow
• If flowing, open the down wind diverter valve
• Close annular

6
Shallow Gas Kicks

• Start circulating heavy mud with both pumps
• If all heavy mud used up, pump all mud in mud
  pits
• When this mud is gone, pump sea water
• Continue until well is under control
• may deplete
• or bridge

7
Subsea Well Control

• Floating rigs
• BOP stack on sea floor
• Communication from the wellbore to surface
  through riser

8
Subsea Well control
Kill Line
Choke Line Booster Line BOP
9
Subsea Well control

• Riser is not designed to contain pressure
• If the riser is evacuated, it will collapse
• There is a telescoping joint at the top
• Choke and kill lines to circulate kicks through
• PVT and flow indicators affected by heave of
  vessel

10
Effect of choke and kill line

• Possibly high CLFP during kicks
• u-tube effect as gas hits choke line
• Gas in top of BOP stack
• Kill riser after killing well