| abstract |
A method of controlling lost circulation includes introducing into a wellbore a lost circulation fluid comprising: an external oil phase, an internal aqueous phase, an emulsifier, a wetting agent, a magnesia sealant, and a; retarder; contacting the lost circulation fluid with a lost circulation zone; and forming a plug adjacent the lost circulation zone by reacting the magnesia sealant with water at a wellbore temperature, thereby reducing fluid loss into the lost circulation zone. |