Study On High Temperature And High Density Saturated Brine Drilling Fluid System

Compared with conventional drilling, the drill fluid which is used for deep well drilling asks for higher request, because the temperature is the primary factor which influence the deep well drilling fluid. The filtration property and rheological property of the drill fluid is always the technology difficulties to the deep well drilling. And the formation pressure of the deep well is often very high, so it needs the higher density drilling fluid. But the solid phase in the high density drill fluid is large, which will increase the possibility of the borehole problems, such as differential pipe sticking, circulation lost, blowout. It is difficult to ensure that the good filtration property and rheological property of the drill fluid.Through the current situation of research on the high temperature and high density water-based drilling fluid at home and abroad, we clearly understand the technical difficulties and development trend. And from technology principle, we analyze the performance requirements of high density water-based drilling fluid and the main influence factors, from which we know that the good performance of the high density water-based drilling fluid system mainly depends on the harmonious and unified of the rheological property, building capacity and rejection capability. Therefore, it is needed to optimize the treating chemical to ensure that various performance of the high density saturated saltwater drilling fluid meet the requirements under the high temperature.We have used the analysis method of the single factor to screen the conventional chemical for the high density drill fluid and optimize the added amount. Finally, five sets of saturated saltwater high density drill fluid which is high temperature resisting are selected, in which the type of chemical is few but better.① three sets of saturated saltwater mud whose density is 2.40g/cm3, and resistance to high temperature of 180～220℃;② two sets of saturated saltwater mud whose density is 2.50g/cm3, and resistance to high temperature of 180～200℃. And evaluate the comprehensive performance of the five sets of drill fluid system respectively. The results show that the five sets of drill fluid have advantages of good rheological property, lubricity, building capacity and sealing characteristics, these features can satisfy the different conditions of deep well drilling requirements. Moreover, this paper has a exploratory research on a kind of saturated saltwater drill fluid which density is 2.60g/cm3, and high temperature resisting.