Development of drilling fluid technology during the "Ninth-five-year" plan in Daqing Oilfield

The development on drilling fluid technology during the Ninth-five-year plan in Daqing Oilfield is briefed in this paper, mainly focuses on wellbore stability, high temperature deep well drilling, under-balanced drilling, formation protection and improving the cementing between two interfaces, etc. Many new drilling fluid systems have been developed, in which there are water based weighting drilling fluid, its better lubricity and shale control ability ensure the smooth drilling of sidetracking horizontal well. The polymer drilling fluid has strong inhibition, and solves such problems as wellbore instability, sticking and lost circulation, and good for slim hole drilling and completion. Other new systems such as water-in-oil drilling fluid, oil-in-water drilling fluid , silicon-based drilling fluid, potassium formate drilling fluid, etc, all have stable performances and high temperature tolerance, and they effectively protect formation and improve cementing quality. Some disadvantages and the developing tendency on drilling fluid technology are also pointed out.