Lost Circulation Material Mean?
Lost circulation material (LCM) refers to additives introduced to the drilling fluid when there are signs of inadvertent returns or the loss of drilling fluid into the formation.
Lost circulation materials are intentionally introduced into the mud system to stop the flow of drilling fluid into a thief zone or a weak formation.
The LCM is usually waste products from the food processing and chemical manufacturing industries. The material is generally fibrous or flaky in nature so that it will bridge over and seal zones where drilling fluid loss is occurring.
Trenchlesspedia Explains Lost Circulation Material
Lost circulation material (LCM) commonly used are fibrous, flaky or granular.
Fibrous LCM includes:
- cedar bark
- shredded cane stalks
- mineral fiber
Flaky LCM includes:
- mica flakes
- plastic pieces
- cellophane sheeting
Granular LCM includes:
- ground and sized limestone or marble,
- nut hulls,
- cotton hulls
LCM added to the drilling fluid increases the maximum particle size in order to plug the thief zones, pores and cracks which the mud by itself cannot seal. To do this effectively, the fluid must contain particles large enough to lodge themselves in the largest apertures.
Since mud pumps can only handle up to a certain size of particles, the size of the openings that can be sealed using LCM is limited.