Equivalent Circulation Density (ECD)
Equivalent Circulation Density (ECD) is the dynamic density of circulating mud in a borehole and is used to calculate the pressure exerted on the borehole wall when the mud is being circulated. Any fluid column exerts a pressure equivalent to its hydrostatic head on the walls of its container. Similarly, the drilling fluid also exerts pressure on the borehole, which is equivalent to the hydrostatic pressure of the mud column and is a function of the mud density. However, the pressure effect changes in dynamic conditions and is reflected as Equivalent Circulation Density (ECD).
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