Lost circulation is drilling fluid escaping into the formation instead of returning to surface. A lost circulation material (LCM) seals the openings that the fluid is escaping through. Ironstone supplies the full range — fibrous, flaky, granular, and resilient graphite — with a certificate of analysis for every batch. For a step-by-step selection by loss severity, see the LCM selection guide.
Loss severity decides both the material and the particle size. Small, slow losses need fine bridging material; large losses need coarse blends or a squeeze; complete losses may need a cement plug rather than LCM. The three particle shapes seal differently, and most treatments blend them:
| Type | How it seals | Best against |
|---|---|---|
| Fibrous | Fibers mat together across an opening to form a base for other solids. | Seepage and the start of a bridge in porous or fractured rock. |
| Flaky | Flat flakes overlap and plate across the wellbore face. | Porous formations and building a cake over a wide face. |
| Granular | Graded particles wedge into openings, sized largest-first. | Bridging fractures and larger openings; the core of severe-loss blends. |
| Resilient graphite | Deformable carbon that compresses into an opening and springs back to hold the seal as pressure changes. | Fractured formations where a rigid bridge would be pumped back out. |
Resilient graphite is a graded carbon material that is deformable rather than rigid. When it enters a fracture it compresses to fit the opening, and it springs back to keep the seal in place as downhole pressure rises and falls — where a hard, brittle particle would crush or be pumped back out. That resilience is why it is valued for fractured and pressure-cycling formations. Our resilient graphite page covers the grades and particle-size ranges.
When an LCM is used across a producing zone, material that dissolves in acid can be cleaned out later so it does not block production. Calcium carbonate (sized marble) is the common acid-soluble bridging material and is the default for drill-in and completion fluids. Fiber, flake, and graphite LCM are generally not acid-soluble, so they are used where the sealed interval is not a production zone. Tell us whether the zone is producing and we will quote accordingly.
Any LCM pumped while a downhole motor or measurement tool is in the string must be fine enough to pass through the tool without plugging it, and through the bit nozzles. That rules out coarse blends and limits you to fine fiber and fine graded material at controlled concentration while the motor is in the hole. For a serious loss that needs a coarse squeeze, the usual practice is to pull the motor first. The selection guide covers the particle-size limits in detail.