WISR Ltd V.WZR

Well Kill Operations

[harry_reele]

The intention of a well kill (or the reality of an unintentional well kill) is to stop reservoir fluids flowing to surface. This of course creates problems when it is desirable to get the well flowing again. In order to reverse the well kill, the kill fluid must be displaced from the well bore. This involves injecting a gas at high pressure, usually nitrogen since it is inert and cheap. A gas can be put under sufficient pressure to allow it to push heavy kill fluid, but will then expand and become light once pressure is removed. This means that having displaced the kill fluid, it will not itself kill the well. The reservoir fluids should be able to flow to surface, displacing the gas.

The cheapest way to do it is similar to bullheading, where the nitrogen is pumped in under high pressure to force the kill fluid into the reservoir. This, of course, runs a high risk of causing well damage. The most effective way is to use coiled tubing, pumping the gas down the coil and circulating out the bottom into the well bore, where it will displace the kill mud to production.