Oil-based drilling fluid has such remarkable advantages as strong inhibitive ability, high temperature tolerance, good pollutant resistance, oil & gas reservoir protection, good lubricating property, strong corrosion resistance, etc., has experienced the development history from crude oil, water-free oil base (diesel), water in oil (diesel), low colloid water in oil, low toxicity water in oil and water-free oil base (white oil), and presently serves as a primary means in drilling deep well, highly-deviated well, horizontal well and various complex strata.



Since 1980s, oil-based mud is successively used at oilfields of Huabei, Xinjiang, Zhongyuan, Daqing, etc. Oil-based mud has a rather limited application in China due to its high cost, but many foreign countries have always been using oil-based mud in drilling deep well, ultra-deep well, highly-deviated directional well, horizontal well and water-sensitive complex strata, as well as in protecting oil & gas reservoirs.
From 1950s to 1960s, water-free oil-based drilling fluid
              Water-in-oil emulsion drilling fluid with diesel as base oil
In the 1970s, activity-balanced water-in-oil emulsion drilling fluid
              Low colloid water-in-oil emulsion drilling fluid
In the 1980s, low toxicity water-in-oil emulsion drilling fluid with mineral oil as base oil



Since the 1990s, with the purpose of further improving the cuttings carrying ability of oil-based drilling fluid, increasing the rate of penetration and mitigating the damage to environment, some new systems have been launched and oil-based mud technology makes new progress.



At present, along with further exploration and development, there will more and more complex wells, such as deep well, highly-deviated well, extended reach well, complex stratum well, etc. and oil-based drilling fluid will be the primary means in solving these complicated problems. Water-free oil-based drilling fluid is still in the stage of study, test and improvement in China. Although oil-based drilling fluid is high in cost, it can solve difficult problems that are hard for water-based drilling fluid to settle, and will reduce complex situations, increase the rate of penetration and lower the total drilling cost, so it has an extensive application prospect.