Lost circulation occurs when there is a continuous loss of whole mud into permeable formations, fractures or voids. To cure the loss of whole mud the zones must be plugged so that a filter cake can be formed.

In diamond drilling the loss of returns above the water table may result in a dry hole which can cause problems when landing the core barrel inner tube. Lost circulation materials may be divided into fibres, flakes and granules. In general, fibres and flakes are more effective in low density muds and are more applicable to diamond drilling and water well drilling.

Care should be taken when drilling into aquifers using loss circulation materials to avoid plugging of the aquifer and subsequent bore development problems. AMC has a range of lost circulation products which are designed to cover most drilling applications.