drilling · well control
Kill Sheet Circulating Pressures (ICP/FCP)
ICP = SCRp + SIDPP; FCP = SCRp × (KWM / MW)
click formula to derive ↑
Inputs
psi
psi
lb/gal
lb/gal
Description
Calculates the two endpoint circulating pressures — Initial Circulating Pressure (ICP) and Final Circulating Pressure (FCP) — used to complete a standard well control kill sheet for either the driller’s method or wait-and-weight method.
Variables
| Symbol | Unit | Description |
|---|---|---|
| ICP | psi | Initial Circulating Pressure |
| FCP | psi | Final Circulating Pressure |
| SCRp | psi | Pump pressure recorded at the slow circulating rate (kill rate) with the original mud in the hole — must be recent and at the same rate planned for the kill. |
| SIDPP | psi | Stabilized shut-in drillpipe pressure from the kick. |
| MW | lb/gal | Mud weight in the hole at the time the well was shut in. |
| KWM | lb/gal | Kill mud weight calculated from the Kill Mud Weight calc — the weight the mud will be raised to before or during the kill circulation. |
Assumptions
- Slow circulating rate pressure (SCRp) was recorded recently, at the same pump rate that will be used for the kill, with the original mud in the hole
- Pump rate is held constant throughout the kill circulation — ICP/FCP are only valid at the SCR pump rate they were derived from
- The FCP approximation (scaling SCRp by the mud weight ratio) is a standard simplification that does not separately account for the typically small change in frictional pressure loss from a viscosity change between original and kill mud
Limitations
- Does not account for choke line friction in subsea/deepwater configurations — a choke line friction correction must be added to both ICP and FCP for those wells
- Assumes a single, uniform original mud weight in the drillstring at the start — does not handle a partially gas-cut drillstring
- Gives only the two endpoint pressures, not the full strip/pressure schedule between them (typically linear by pump strokes on a rig kill sheet)
Use Cases
- → Wait-and-weight kill sheet completion: Calculate the two endpoint circulating pressures needed to fill out a wait-and-weight kill sheet before beginning the kill circulation.
- → Driller’s method second circulation planning: Determine the FCP target for the second (kill mud) circulation of the driller’s method, after the kick has already been circulated out on the original mud at ICP.
- → Well control drill / training: Practice computing ICP and FCP from a given SCR pressure, SIDPP, and kill mud weight as part of rig crew well control certification.
Related Calculations
Region Notes
Permian Basin
Typical Permian Basin SCR pressures at standard kill rates (3-5 bpm) run 200-500 psi for intermediate/lateral sections — verify against the actual pre-recorded SCR sheet for the specific rig and BHA rather than using a generic default.
Gulf of Mexico
Deepwater wells must add a choke line friction pressure to both ICP and FCP that this calculation does not include — consult the rig’s well control procedures for the applicable correction.
Global
SCR pressure must be re-recorded any time the pump rate, BHA, or mud properties change significantly — using a stale SCR value is a common source of kill sheet error.
References
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