LOW FLUID LOSS DRILLING FLUID COMPOSITIONS COMPRISING DIBLOCK COPOLYMERS

摘要

The invention relates to a selectively hydrogenated isoprene-styrene diblock copolymer having a polystyrene content of at least 40 wt. %, which when added to an oil-based mud composition, substantially reduces fluid loss. The polystyrene in the diblock has a true molecular weight greater than 60 kg/mole and the total apparent molecular weight of the diblock copolymer is at least 160 kg/mole. The drilling mud that contains about 0.5 pounds per barrel to about 10 pounds per barrel of a selectively hydrogenated isoprene-styrene diblock copolymer and a weighting agent, resulting in a drilling fluid composition exhibiting good suspension of the weighting agent and improved fluid loss performance.

主权项

1. A drilling fluid comprising an oil-based mud and a selectively hydrogenated isoprene-styrene diblock copolymer having at least a 40 wt. % polystyrene content wherein the fluid loss property of the drilling fluid is reduced.