Few situations put the solids-control engineer and the mud engineer at odds like lost circulation. One wants the shaker removing solids; the other has just added a load of lost-circulation material that must stay in the mud to bridge the loss zone. Most of that LCM is too coarse to pass the screen, so the shaker throws it straight out with the cuttings. The obvious fix — open the screens or bypass the shaker — quietly sets up the next round of losses. Here is the conflict, and the way through it.
Why the shaker eats your LCM
Lost-circulation material — sized calcium carbonate, graphite, fibres, nut plug — works by bridging and sealing the pores or fractures where mud is escaping. To do that it has to be coarse, often in the same size range as, or larger than, the cuttings. And that is the problem: most LCM is too large to pass through a normal shaker screen, so on the very first circulation it is retained on the screen and discarded with the drill cuttings. Coarse LCM won’t pass a 20-mesh screen; only the finest grades make it through a fine deck.
So the moment you pump LCM and keep drilling over the shakers, you are also throwing much of it away — and having to add more to replace it, at real cost. The instinctive reaction on the rig floor is to stop the screens from eating it: fit a much coarser screen, or bypass the shakers altogether so the returns skip the deck. That keeps the LCM in the system. It also opens a second problem that is easy to miss in the moment, which is exactly the trade-off Rig IQ is built to weigh before you make the call.
The trap: bypassing to save LCM builds the losses back
Here is the part that catches crews out. When you bypass the shakers or run coarse screens to keep the LCM, you also stop removing drilled solids. They accumulate in the mud, and as they build, they raise density and rheology. Higher rheology means more annular friction, and more friction means a higher equivalent circulating density. The standard field guidance is blunt about it: don’t bypass the shakers or fit coarser screens to treat with LCM, because the rising drilled-solids load pushes ECD up — and a higher ECD encourages more losses.
So the shortcut is self-defeating. You opened the screens to keep the material that seals losses, and in doing so you drove the ECD that causes them. In a well already near its fracture gradient, that can turn a manageable seepage into a fight. The engineering point is that LCM retention and drilled-solids removal are coupled problems — you cannot solve one by simply switching off the other — and holding both in view at once is precisely what Rig IQ helps you do rather than trading one loss for another.
The way through: recover, size, and stage
The better answers keep the LCM without surrendering solids control. The cleanest is a dedicated LCM-recovery screen or scalping unit: a coarse deck that catches the LCM off the top and returns it to the system, while the main shakers keep removing the finer drilled solids underneath. Where that isn’t available, matching the LCM grade and pill to the screen you must run — and accepting some loss and re-addition as a planned cost — beats blindly bypassing. Degradable or sized LCM designed to pass and re-seal, and treating losses in discrete pills rather than continuously, both reduce the tension.
Underneath the tactics is a design principle from wellbore-strengthening practice: the bridging material is engineered to a particle-size distribution matched to the formation — commonly a spread of sizes with a median near a third of the fracture width — not just dumped in coarse. Treating LCM as a sized, recoverable component of the system, rather than a sacrificial additive the shaker destroys, is the shift that resolves the conflict. Planning that balance — grade, screen, recovery and ECD headroom together — is the kind of call Rig IQ is built to work through.
The conflict, in short
The problem: LCM must stay in the mud to seal losses, but most LCM is too coarse to pass the shaker screen — so it’s discarded with the cuttings and must be re-added.
The trap: bypassing shakers / coarse screens keeps LCM but stops removing drilled solids → density & rheology rise → ECD climbs → MORE losses.
The fix: dedicated LCM-recovery (scalping) screen · sized/degradable LCM · discrete pills · PSD matched to the formation — keep the LCM without surrendering solids control.
LCM has to stay in the mud to seal losses, but most LCM is too coarse to pass the shaker screen, so it’s discarded with the cuttings. Bypassing the shakers or fitting coarse screens keeps the LCM but stops removing drilled solids — which raises rheology and ECD and encourages more losses. The fix is to keep both goals: a dedicated LCM-recovery (scalping) screen, sized or degradable LCM, discrete pills, and a PSD matched to the formation — not blanket bypassing.
Common questions
Why does the shaker remove lost-circulation material?
Because LCM works by bridging pores and fractures, it has to be coarse — often as large as or larger than the cuttings. Most LCM is therefore too big to pass through a normal shaker screen, so it is retained on the deck and discarded with the drill cuttings on the first circulation, and must be re-added to maintain the treatment.
Should you bypass the shakers when treating with LCM?
Generally no. Bypassing the shakers or fitting much coarser screens keeps the LCM in the mud but also stops removing drilled solids. Those solids accumulate, raising density and rheology, which increases the equivalent circulating density — and a higher ECD encourages more losses, defeating the purpose. It trades one problem for a worse one.
How do you keep LCM without losing solids control?
Use a dedicated LCM-recovery or scalping screen that catches and returns the coarse LCM while the main shakers keep removing finer drilled solids. Combine that with LCM grades sized to the screen and the formation, degradable or re-sealing products, and treating losses in discrete pills rather than continuously bypassing — so you retain the sealant without letting drilled solids and ECD climb.
