Analysis of drilling fluid rotational viscosity tests subjected to double cylinder moments

Abstract:

The viscosity of fluids can directly reflect the characteristics of different fluids， and its measurement is of great significance in identifying the quality of fluids and determining their direction of use. For example， the change of drilling fluid viscosity will affect the realization of lubricating oil function， and the viscosity parameter as a basis for the selection of the drilling fluid is particularly critical for the measurement of the viscosity of the drilling fluid. However， in the traditional rotary viscometer， the friction moment of the liquid acting on the whole inner cylinder is calculated to be large because the additional moment generated in the lower plane of the inner cylinder also acts on the spring at the same time， and the velocity gradient and shear stress at each point on the bottom flat surface are different， which makes the problem more complicated. In this paper， based on the traditional rotating cylinder viscometer structure， the calculation principle is improved and supplemented， and by using finite element software to analyze the flow characteristics of the double cylindrical winding flow， the simulation results are consistent with the theoretical analysis， which verifies the reasonableness of the derived formula. Applied to the flow characteristics of drilling fluid in intact formation， it can provide a basis for further research on the shear stress of drilling fluid in fractured formation， and provide support for the prevention of in-hole accidents.

Key words:drilling fluid;rotational viscometer;viscosity measurement;finite element;numerical analysis