Taking a Kick
This is what happens when 8,000+ units of gas comes to surface. It’s stunningly beautiful, IMO, but also dangerous if managed improperly. I can’t get into the fine details of the event, but I think there is still a pretty good story about its management.
When our well kicked, fluid forced its way up the wellbore, seeking open atmosphere, and tripped an alarm on the driller’s control panel, showing “a pit gain” of 5m/3 in the tanks. Sure-fire signs a kick is taking place are fluid gain, pressure fluctuations and hook load changes.
With eyes on his drill screen, watching flow rates and pressure changes, the driller activates the BOP’s preventative measures: closing the pipe rams and shutting the bag to prevent fluid from escaping.
We’re drilling deep into the earth’s crust where faulted formations can have hidden pressures, and a well “kicks” whenever the formation pressure exceeds the well’s hydrostatic pressure. Hydrostatic pressure is the weight of the well’s column of fluid, which is shaped by density (kg/m3), depth and gravity. When the well becomes underbalanced, no matter how much you pump on it, the natural gas and fluids from the kicking formation flow upward like fluid in a plunger.
Once the well kicks, it’s crucial you don’t lose control. Luckily, the drillers on this rig are experienced and have well-trained floorhands. I was impressed by the entire affair and how routine the situation seemed—company men, tool pushes, drillers and hands all working in sync.
During drilling, the wellbore was full of a lighter-weight water-based brine, poised for drilling optimization. After monitoring the influx, and the well continued pushing at us, the decision was made to displace to heavier, more viscous invert to prevent further gaseous infiltration.
The driller pulled off bottom, shut in the well, and began to monitor for flow and pressures. To kill the well, both derrick hands kicked into overdrive monitoring tank levels and mixing heavy mud.
Once the well is shut in, there is typically a controlled procedure to circulate the influx through the choke line on the BOP manifold. As the rig pumps heavier mud downhole, increasing hydrostatic pressure, an overbalanced position is achieved, and the montney formation is prevented from pushing further up the wellbore.
All the gas that penetrated the wellbore needs someplace to go: mud pumps down the drill string, circulating the gas up the casing line. The gas is diverted through a choke manifold, flowing into a degasser tank where the flare is ignited!
The marvelous flare you see was produced numerous times throughout the killing procedure as the rig bled off the well’s pressure, maintaining control.
As geology, engineering, and raw experience come into play, it is symphonic. I wish I could go further into detail, but I should leave it at that. If you want to talk about drilling, we can have coffee!