Design Principle and Application of High-Performance Water-Based Drilling Fluid System
In order to solve the environmental protection pressure and economic cost increase brought by oil-based drilling fluid,the research and promotion of new water-based drilling fluid are imperative.In this paper,the geological characteristics of shale gas reservoirs were analyzed by XRD and environmental scanning electron microscope experiments.At the same time,the key properties of the water-based drilling fluid,such as plugging,inhibition and lubricity,were evaluated by means of core plugging experiment,rolling recovery rate and lubricity test.The results showed that the high temperature and high pressure filtration loss of the water-based drilling fluid system was less than 6 mL,and the core plugging efficiency reached 83.52%,the rolling recovery rate of the system for red soil and shale outcrop(in a certain area)of Longmaxi formation was above 95%,which showed that the system had stable rheology and fluid loss wall-building properties,and had strong plugging and inhibition ability;the friction coefficient of the drilling fluid system was 0.0804,the viscosity coefficient of the formed filter cake was 0.0753,and the drilling fluid system had good lubrication ability;in the range of 100～160℃,the drilling fluid system maintained relatively stable rheology and fluid loss wall-building properties,and had good temperature resistance.The system had good plugging and inhibition capabilities,being close to the effect of oil-based drilling fluid,could save drilling costs,and had broad application prospects.
Shale gasWell wall stabilityWater based drilling fluid systemSystem evaluationApplication prospect
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