Patent ID: 6986396

Claim:
A method for measuring in real time or near real time the effectiveness of a sweep for cleaning a borehole drilled with drilling fluid, said method comprising: providing the volume, density, and at least one rheological property of the drilling fluid; providing a baseline equivalent circulating density of said drilling fluid; providing the volume, density, and at least one rheological property of the sweep; pumping said sweep into said borehole and circulating said sweep in said borehole; measuring in real time or near real time the downhole density of said sweep during said pumping and during said circulating of said sweep as a function of time and measuring in real time or near real time the pump rate during said pumping; providing the specific gravity of the subterranean formation; calculating in real time or near real time the total equivalent circulating density; determining in real time or near real time the sweep's contribution to the total equivalent circulating density; and calculating in real time or near real time the sweep efficiency.