In wells subject to lost circulation problems, losses are normally encountered during drilling when the borehole is being formed, and are dealt with at that stage. However, even after the hole has successfully been drilled new losses may sometimes occur, for example as a result of an increase in fluid density or the failure of a previous lost circulation treatment. Lost circulation encountered during cementing can be addressed in a similar fashion to that used during drilling, either by the placement of a ‘pill’ to seal the loss zones before cementing or by the use of bridging and plugging agents in the cement slurry itself.
Mica can be incorporated into cement slurries as well as drilling fluids, and can bridge large fractures efficiently as a result of its plate-like shape. It is available in three different size grades, to be selected according to the nature of the fractures and losses experienced. To find the product adapted to your issue go to our mica page.
The cellular structure of expanded perlite contributes to its excellent bridging properties. The low density of perlite also helps reduce slurry density whilst maintaining solid volume fraction, and this combination makes it and ideal cement additive to combat lost circulation problems.
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