ECD (equivalent circulating density) is the dynamic density exerted by acirculating mud at any point in the borehole. ... So the equivalent circulating density (ECD) is the sum of this pressure loss (converted todensity) and the original mud densityof the drilling mud under static .
The effective density exerted by a circulating fluid against the formation that takes into account the pressure drop in the annulus above the point being considered. The ECD is calculated as: d + P/(0.052*D), where d is the mud weight (ppg), P is the pressure drop in the annulus between depth D and surface (psi), and D is the true vertical depth (feet). The *ECD* is an important parameter in avoiding kicks and losses, particularly in wells that have a narrow window between the fracture gradient and pore-pressure gradient.