Fremgangsmåte for å forsinke herdetiden til vandige tverrbundne sirkulasjonssvikt-kontrollpiller

摘要

There is disclosed a method of delaying the setting time of aqueous lost circulation control pills. The aqueous lost circulation control pills contain a crosslinkable polymer viscosifier, one or more water retention additives, a crosslinking agent, a pH control agent, and a crosslink time regulator. The method comprises utilizing as the crosslink time regulator encapsulated sodium chloride. The preferred crosslinkable polymer is xanthan gum. The preferred water retention additives are pregelatinized starch and a polyanionic cellulose derivative. The preferred crosslinking agent is a hydrated borate. The preferred pH control agent is magnesium oxide. Preferably the sodium chloride is encapsulated with a urethane coating.