Lost Circulation Control in Drilling
Lost circulation is a flow-path problem, not a single-product problem. The first task is to determine whether drilling fluid is entering natural fractures, vugs, a highly permeable interval or a drilling-induced fracture, then select a treatment that can be pumped through the actual circulation system.
Diagnose the loss before selecting LCM
Record when the loss started, whether returns were reduced or lost completely, the formation being drilled, recent pressure or circulation changes and the response to previous treatments. A treatment that works for seepage into a permeable interval may not be suitable for a large fracture or an induced-loss event.
Focus on materials that can form a low-permeability mat or bridge across the flow paths without creating unnecessary pumping restrictions.
The treatment may need a broader distribution of shapes and sizes, including fibrous, swelling or sized bridging components.
Review equivalent circulating pressure, mud density, rheology and operational pressure before assuming that more LCM alone will solve the problem.
Check bit nozzles, screens, motors, mud pumps and any other restriction before selecting large particles or long fibers.
LCM should be evaluated in the active mud because rheology, solids, salinity and polymers affect suspension and placement.
Decide whether the material will be circulated continuously, spotted as a pill or used in a staged treatment based on the operation and risk.
FRACPLUG and SEALFIBER roles
FRACPLUG is the Mudolog swelling LCM component for fractured, vugular and highly permeable formations. SEALFIBER is the fibrous LCM component used to support bridging and mat formation across permeable or fractured flow paths. They can be evaluated separately or together with suitable sized granular materials when the treatment design requires multiple sealing mechanisms.
Information to send for a recommendation
Send the drilling method, hole size and depth, mud type and density, approximate loss trend, formation description, circulating conditions, solids-control equipment, nozzle or screen restrictions, previous LCM treatments, temperature and destination country.
Frequently Asked Questions
What causes lost circulation during drilling?
Losses can occur when drilling fluid enters natural fractures, vugs, highly permeable zones or drilling-induced fractures. The loss mechanism should be separated from simple fluid-loss filtration before selecting a treatment.
Should every lost-circulation event be treated with the same LCM?
No. LCM should be selected from the loss severity, likely opening size, formation type, mud system, circulating equipment and any restrictions imposed by screens, nozzles or downhole tools.
Can fibrous and swelling LCM be used together?
They can be complementary when the treatment design calls for both bridging or matting and a swelling component. The final blend should be checked against the actual circulation system and operational constraints.
Which Mudolog products are used for lost-circulation treatments?
FRACPLUG is the Mudolog swelling LCM and SEALFIBER is the fibrous LCM. They may be considered separately or as components of a broader treatment depending on the loss mechanism.