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 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