A PRACTICAL METHOD OF PREDICTION OF MAXIMUM PIPE INTRODUCING SPEED IN BINGHAM FLUID

Pressure surges are closely related with stability of borehole system and the pipe introducing speed is a key factor that influences pressure surges. Therefore determination of rational pipe introducing speed required by balanced drilling and well control is very important for ensuring a safe and fast drilling. Taking Bingham fluid for an example, the paper deduced theoretically a group of non-linear equations of control maximum pipe introducing speed and analyzed the principle factors that influence the maximum pipe introducing speed under conditions of determined formation break-down pressure gradient. The calculated data shown that the maximum pipe introducing speed decreases with increasing of yield point and plastic viscosity of the drilling fluid and enlargement of ratio of outside diameter over inside diameter of the borehole annulus and it increases with increasing of formation break-down pressure gradient. Some calculation samples were also provided in this paper.