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Stojan Petkovic Stojan Petkovic

Well Kill

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Well control

Well Kill

Kill fluid, volumes and pressures for a producing well, or the kill sheet of a drilling well. Pick the method, enter the well, in metric or oilfield units.

Before you use the tools

The tools and calculators on this site are personal, informational aids made from public formulas and stated assumptions.

  • Results are approximate. They are not a design, a procedure or professional advice.
  • Do not use them as the only basis for work on wells, work under pressure, work with nitrogen or any other safety-critical action. Follow your company's procedures, the manufacturer's data and the instruction of the responsible person.
  • This is a personal, independent site. It does not represent any employer or company and uses none of their data. You are responsible for the data you enter and for your decisions.
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Method

Producing well kill, or a drilling well killed by one of the two circulation methods

Well and fluid
m

Depth of the formation

m

Measured depth of the tubing shoe

kg/m³
bar
Kill and bullheading
bar

Pressure the kill fluid adds over the formation pressure

bar

Pressure above the formation pressure needed to push fluid into it when bullheading

bar

At the formation depth; 0 leaves the check out

Tubing and casing
mm
mm
mm
Pumping
L/min

Inputs

Result

Kill fluid density

–

Formation pressure
–
Density increase
–
Hydrostatic pressure of the kill fluid
–
Tubing volume (bullhead)
–
Annulus volume
–
Time to pump the tubing
– min
Time to pump tubing and annulus
– min
Surface pressure at the start of bullheading
–
Surface pressure at the end of bullheading
–
Bottomhole pressure while injecting
–
Margin to fracture pressure
–

Method

The tool calculates the kill from the balance of hydrostatic pressures.

  1. Hydrostatic pressure: P = ρ·g·TVD, with g = 9.80665 m/s². The formation pressure is the shut-in pressure plus the hydrostatic pressure of the fluid in the well.
  2. Producing well: the kill fluid density balances the formation pressure plus the overbalance, ρ = (P + overbalance) / (g·TVD). Volumes are π/4·ID²·L for the tubing and π/4·(casing ID² − tubing OD²)·L for the annulus.
  3. Bullheading: the surface pressure is the injection pressure (formation pressure plus the pressure needed to inject) minus the hydrostatic pressure of the fluid in the tubing. It starts at the shut-in pressure plus the injection margin and falls as the kill fluid goes in. The bottomhole pressure is checked against the fracture pressure.
  4. Drilling well: kill mud density = mud density + SIDPP / (g·TVD). ICP = SIDPP + circulating pressure at the kill rate; FCP = circulating pressure × kill mud / mud density. The drill pipe pressure falls linearly from ICP to FCP over the strokes to the bit.
  5. Wait and weight circulates once with the kill mud. The driller's method circulates the influx out with the original mud first, holding ICP, and then circulates the kill mud. MAASP = (leak-off density − mud density)·g·shoe TVD.

Assumptions

  • A vertical column of one fluid: no gas in the fluid, no friction while bullheading and no temperature or compressibility effect on the density.
  • Pressures are gauge. Check the kill against the casing, tubing and wellhead pressure ratings.
  • The kill sheet is for the method the page names; choke operation and the response to a gas influx need judgement on location.

This tool is a planning aid, not a substitute for the operator's well control procedures and the well control certification of the crew. Check the result against the company's own kill sheet.

The tools are aids for engineers. Check the inputs and the results: responsibility for any decision stays with the user.