Most solids-control losses are invisible not because they are hard to see, but because no one is writing them down. A separation train can drift for an entire section while every individual reading still looks “about normal,” because nobody is watching the trend. The fix is unglamorous and almost free: a one-page report, the same fields every tour, plotted against footage. This is what belongs on it, and how to read each line.
The principle: a snapshot lies, a trend tells the truth
Any single reading can be explained away. Dilution is up — but we drilled a long shift. The funnel climbed — but we just added barite. Taken alone, each number is noise. Taken tour over tour against footage, the same numbers become a diagnosis: a four-point drop in removal efficiency overnight, a feed head that has crept down all week, a sand reading that has doubled since the screens were last changed. The report’s only job is to convert isolated readings into a trend you can act on.
The one-page report
| Metric | Where it comes from | Read it as a warning when… |
|---|---|---|
| Removal efficiency (η) | Mass balance off the daily reports | It drops several points overnight — solids slipping back to the active |
| Dilution (bbl/day) | Pit and mixing records | It rises with no change in ROP — money leaving one barrel at a time |
| LGS % (and MBT) | Retort split + methylene blue test | LGS climbs (equipment missing solids); MBT climbs too (reactive clay dispersing) |
| Sand content % | API sand test, flowline vs suction | Suction-side number rises — coarse solids bypassing shakers/desanders |
| Cone feed head / manifold psi | Manifold gauge ÷ mud weight | Head drifts below ~75 ft — usually a worn feed-pump impeller |
| Centrifuge hours / duty | Equipment log | Hours fall behind fines generation, or the duty is wrong for the mud |
| Screen inventory & changes | Shaker log | Panels worn or holed, or changed without recording the cut |
| Oil-on-cuttings % (OBM/SBM) | Retort on a discard sample | Above the 3–5% benchmark — fluid and compliance leaving on the cuttings |
None of these need new instrumentation. Every input already exists somewhere on the rig — the report’s value is simply gathering them in one place, every tour, so the drift has nowhere to hide.
From report to action
The point of writing it down is to shorten the distance between a problem starting and someone fixing it. A crew that reports η and feed head every shift catches a failing impeller in hours — while the rig that measures nothing only discovers it at the reserve-pit audit, after the dilution has already been built, circulated and discarded. The report is not paperwork; it is the difference between a fault you catch in a tour and one you pay for across a section.
Key takeaways
Track the same handful of numbers every tour — η, dilution, LGS/MBT, sand, feed head, centrifuge hours, screen changes, and OOC on non-aqueous mud — and plot them against footage rather than just the calendar. Treat any drift as a fault to diagnose, not a cost to absorb. The equipment on the deck only saves money when someone is reading it; the daily report is how you make sure someone is.
