Optimizing drilling mud shearing

Abstract

Viscosity and other properties are determined at desired temperatures in drilling mud and other fluids by using a versatile cavitation device which, operating in the cavitation mode, mixes and heats the fluid to a specified temperature, and, operating in the shear mode, acts as a spindle for application of Couette principles to determine viscosity as a function of shear stress and shear rate. The invention obviates the practice of adjusting rheology of a drilling fluid by passing it through the drill bit. Drilling fluid may be managed by a 'straight-through' method to the well, or by placing the cavitation device in a loop which isolates an aliquot of known volume and circulating the fluid through the loop including the cavitation device. A controller may be programmed to manage the viscosity and other properties at various temperatures by controlling the power input and angular rotation of the 'spindle' (which has cavities on its cylindrical surface), and feeding viscosity-adjusting agents and other additives to the fluid. Data may be collected from the loop and used in the “straight-through” mode until it is determined that conditions require a new set of data, or the loop may be used continuously. The system may be used with a supplemental viscometer, density meter, and other instruments.