The kill mud weight is arithmetic. So is ICP. The part that goes wrong at three in the morning is the drill pipe pressure step-down: eight or fifteen rows of interpolation between ICP and FCP, worked out on the back of the sheet while the choke operator waits. This does it in one tap — every value with its formula and substituted numbers written underneath, in the rounding directions IADC publishes, ready to print and sign.
One-time purchase. No subscription. No account. Works offline on the rig floor.
Pick your step size — every 100 strokes, or a fixed number of steps — and the table is built: strokes pumped, the target drill pipe pressure at that point, and cumulative time at the kill rate. An inline kill graph plots pressure against strokes beside it. This is the calculation crews get wrong by hand, and the reason this is a tool rather than a form.
Kill mud weight rounds up. Leak-off equivalent mud weight rounds down. The pressure reduction schedule rounds down to a whole psi. The rounded values are what get carried into the later steps, exactly as the IADC directions say — so the sheet matches what an examiner or a well control instructor expects to see.
API RP 59 says the slow circulating rates get re-taken when the mud weight changes, the nozzles change, or you drill significant new hole. Every recorded rate is stored with the setup it was taken against, and flagged STALE with the reason the moment that setup moves on. That is the trigger crews miss.
One button produces the whole sheet on paper: well and string data, the slow circulating rate table, every computed value with its formula and substituted numbers, the full step-down schedule with the graph, and signature lines for the driller and the supervisor. CSV export for the sheet and the schedule, JSON export and re-import for the whole well.
| Value | Formula | Rounding |
|---|---|---|
| Formation pressure | MHP + SIDPP | — |
| Kill mud weight | OMW + SIDPP ÷ (0.052 × TVD) | Rounds UP |
| Initial circulating pressure | SCRP + SIDPP | — |
| Final circulating pressure | SCRP × (KMW ÷ OMW) | Rounds DOWN |
| MAASP | (max allowable MW − current MW) × 0.052 × shoe TVD | — |
| Leak-off equivalent MW | LOT MW + LOP ÷ (0.052 × shoe TVD) | Rounds DOWN |
| Annular capacity | (D² − d²) ÷ 1029.4 | — |
| Step-down row | ICP − (ICP − FCP) × strokes ÷ surface-to-bit | Rounds DOWN |
In metric the same sheet uses 0.00981 and 1273236 in place of 0.052 and 1029.4, and switching units converts everything already entered rather than just changing the labels — because a half-converted sheet is worse than no sheet.
Depth, mud weight, shoe depth, the leak-off result, the string geometry and the pump output are meant to be recorded and current before anything happens, not gathered while the well is shut in. The app opens on that setup and keeps it, so the sheet is nine-tenths filled before a kick ever occurs.
It is one screen per hole section, updated on the events the standard names: mud weight change, bit or nozzle change, casing run, and as the hole deepens.
A rate recorded at 10.2 ppg through 12-12-12 nozzles at 10,500 ft is not the rate you have after you weight up, change the bit, or drill another 800 ft. Every reading is stored with the mud weight, nozzles and measured depth it was taken against.
When the current setup no longer matches, the reading is flagged STALE with the specific reason — mud weight changed, nozzles changed, more than 500 ft drilled — and the same warning appears on the kill sheet itself if a stale rate is the one being used.
Under pressure, on a paper form, the two shut-in readings sit in adjacent boxes with near-identical labels. Put the casing pressure in the drill pipe box and every number after it — formation pressure, kill mud weight, ICP, the whole schedule — is wrong in the dangerous direction.
Here they are two visually distinct panels in different colours, on separate sides, each spelled out in full with a line saying which gauge it comes from. Small thing. It is the error that gets repeated.
If the shut-in casing pressure exceeds the initial MAASP, that is on the screen in red: the shoe may already be taking pressure. If the kill mud weight comes out above the maximum allowable mud weight at the shoe, the final MAASP goes negative and is called out. A kill mud weight below the current mud weight, or a zero or negative SIDPP, is flagged as implausible rather than quietly carried into the schedule.
Enter SIDPP, SICP, pit gain and the kill rate. Everything below follows, live, with the working shown.
| Strokes | Drill pipe pressure | Time (min) | Note |
|---|---|---|---|
| 0 | 1,100 | 0.0 | Start — ICP |
| 100 | 1,072 | 3.3 | |
| 200 | 1,044 | 6.7 | |
| 300 | 1,017 | 10.0 | |
| 400 | 989 | 13.3 | |
| 500 | 961 | 16.7 | |
| 600 | 934 | 20.0 | |
| 700 | 906 | 23.3 | |
| 800 | 878 | 26.7 | |
| 1,519 | 680 | 50.6 | Kill mud at bit — FCP |
Well name, rig, date and tour, driller and supervisor, measured depth and TVD, current mud weight, casing shoe MD and TVD, hole size, bit nozzles and pump output.
Drill pipe, HWDP and drill collar OD, ID and length, with internal capacity, annular capacity by section, volumes, and the surface-to-bit and bit-to-surface strokes derived from them.
Pressure for each pump at each kill rate, with the date, time and the mud weight, nozzles and depth it was recorded against — and a stale flag when any of those have moved.
SIDPP, SICP, pit gain and the chosen kill rate, with formation pressure, kill mud weight, ICP, FCP, MAASP initial and final, influx height and estimated gradient computed live.
The full drill pipe pressure step-down for wait-and-weight or the Driller's method second circulation, at your chosen step size, with cumulative time and the kill graph.
Printable kill sheet with signature lines, CSV of the computed sheet and of the step-down table, and JSON export and re-import of the whole well setup between tours and devices.
Multiple saved wells with a picker, so a rig running more than one hole section keeps each pre-recorded data sheet separate.
It does not control a well, does not make the decision to shut in, and does not replace your well control certification, your operator's well control policy, API RP 59, API STD 53, or the judgement of the person on the brake. It computes a kill sheet from the numbers you enter and shows the formula and the substituted values for every result so the work can be checked by hand. Verify every value against your own sheet before acting on it.
Everything stays on your device. Nothing is uploaded, no account is created, and the app keeps working when the lease road has no bars.