AQUEOUS DRILLING FLUIDS FOR DUAL POLYMER ENCAPSULATION

摘要

An aqueous drilling fluid is provided for use in steam assisted gravity drainage (SAGD) recovery of bitumen from oil sands. The aqueous drilling fluid consists of at least two oppositely charged water soluble polymers. The drilling fluid causes the encapsulation of bitumen to prevent the accretion thereof on the drill string and other equipment which comes into contact with zones of rock or soil containing bitumen. A method of providing more efficient encapsulation of the bitumen is provided. The method comprises of applying two oppositely charged polymers either sequentially or simultaneously.