Glycol mud improves drilling performance in Chinese fields

Growing demand for oil and gas has driven drilling activities to deep formations and complex well structures. Drilling fluid must be able to maintain wellbore integrity and thermal stability over extended drilling time. Besides, drilling fluid should produce high rate of penetration (ROP) and low damage to formation rock. Glycol mud satisfies these criteria thanks to its unique cloud point phenomenon. When temperature exceeds cloud point temperature, glycol starts precipitate from mud by forming micelles, coats the rock surface, and plugs the small fractures in rocks. As a result, the flow of mud into rocks is restricted and wellbore stability is improved. This paper surveys more than 40 wells that were drilled with glycol mud. Field cases reported good wellbore integrity, thermal stability, high ROP, and low formation damage. Glycol mud is an excellent choice for battling well instability and high temperatures.