Evidence
Every performance number on this site can be checked against work published by other people. This page sets out what the industry literature reports about invisible lost time, why it is larger than recorded non-productive time, and where the recoverable days actually sit. Nothing here is our own measurement — the sources are named so you can read them yourself.
Non-productive time is the downtime everyone already records — a failure, a stuck pipe, waiting on weather. It appears on the morning report and in the NPT ledger.
Invisible lost time is different. It is the gap between how long a routine operation took and how long it should have taken. A connection that takes eleven minutes against a nine-minute benchmark loses two minutes. Nothing broke, nobody stopped work, and the loss never appears in any report. Repeat it four hundred times across a well and the days are gone.
The industry framing is consistent on this point: ILT sits inside productive time, which is precisely why conventional reporting cannot see it.
A joint drilling contractor and operator initiative in the Bakken reduced unconventional well delivery times by as much as forty per cent by standardising the well construction process and monitoring KPIs. The published account describes it as a capital-free opportunity — no new equipment, only consistency.
Nabors and operator, North Dakota Bakken · reported in Drilling Contractor (IADC), 2017A study of geothermal wells found invisible lost time running at around a fifth of total well time, averaging roughly five days lost per well, with a quantified cost consequence.
Journal of Earth Energy Science, Engineering and Technology · geothermal ILT study, 2020The same geothermal study measured weight-to-weight connection time by crew: the day crew averaged 28.43 minutes per stand against the night crew's 34.65. That is a gap of roughly 22% between two crews on the same rig doing the same work. The pattern repeated across tripping in and out of both cased and open hole.
Geothermal ILT study, 2020 · the crew-gap figure our own scorecard is built to exposeOn a two-well exploration campaign, the first well's invisible lost time represented a quarter of total time taken. Analysing the gap identified five focus areas; on the second well ILT fell to ten per cent, reported as roughly five million dollars of time and cost saved.
Tim Wigham, published account of a two-well exploration campaign, 2018An SPE paper presented at ADIPEC documents an ILT and drilling risk workflow applied for the first time on three UAE onshore wells, combining software and wellbore surveillance to target NPT and ILT reduction against AFE. The work established performance benchmarks including average on-bottom rate of penetration and connection time.
SPE-188640-MS · Abu Dhabi International Petroleum Exhibition & Conference, November 2017Published ILT work converges on the same conclusion: the recoverable time is concentrated in a small number of repeatable operations, not in dramatic failures.
| Operation | Why it holds recoverable time |
|---|---|
| Connections | Performed hundreds of times per well. A two-minute variance against benchmark compounds into days. Most reliably measured as weight to weight. |
| Tripping | Measured per stand, in and out, cased and open hole. Published crew comparisons show consistent differences between tours on the same rig. |
| Rate of penetration | The gap between achieved and achievable ROP for the formation and bit, rather than the gap against an optimistic plan. |
| Flat time | Casing runs, cement waiting, BOP nipple-up, rig moves. Frequently the largest single block of a well and almost entirely within the contractor's control. |
| Rig moves | Highly repeatable between wells on a pad or field, and rarely benchmarked against the fleet's own best. |
Published work makes a distinction worth repeating. Daily drilling reports were the traditional input for ILT calculation and worked, but they could not identify the hidden causes. Later work incorporates high-frequency rig-floor sensor data, breaking activities into smaller measurable sub-activities that can be benchmarked individually.
Others note the obvious risk: if the planned time was unrealistic to begin with, the apparent ILT is not really lost time. That is why a benchmark seeded from a fleet's own measured performance is more defensible than one taken from a plan.
| Source | Where to find it |
|---|---|
| SPE-188640-MS, ADIPEC 2017 | OnePetro — ILT reduction and drilling risk management, UAE onshore field |
| SPE-192319 | SLB technical library — ILT measurement and reduction, ROP and flat time |
| IADC Drilling Contractor, 2017 | Deconstructing invisible lost time, Bakken standardisation programme |
| Journal of Earth Energy Science, Eng. & Tech., 2020 | Effect of invisible lost time on drilling performance of geothermal wells |
| SPE real-time ILT paper, 2022 | Rig-floor sensor data in ILT calculation and reduction |
Questions on any of this, or want the calculation applied to your own fleet's numbers — info@drillx.app