Equivalent Circulating Density (ECD) Using Yield Point for MW less than 13 ppg

Description:

Equivalent Circulating Density (ECD) accounts for the combined effect of mudweight and dynamic pressure losses while circulating drilling fluid.

For mudweights less than 13 ppg, the Yield Point (YP) plays a significant role in estimating ECD.

Equation:

Yield Point (YP) Calculation: $$ \text{YP} = \text{Reading at 300} - (\text{Reading at 600}-\text{Reading at 300}) $$ Equivalent Circulating Density (ECD) Calculation: $$ \text{ECD} = \text{MW} + \frac{0.1 \times \text{YP} \times \text{Q}} {{D_h}-{D_p}} $$

Where:

\( \text{ECD} \) = Equivalent Circulating Density, ppg

\( \text{MW} \) = Mud weight, ppg

\( \text{YP} \) = Yield Point, cp

\( \text{Q} \) = Flow rate, gpm

\( D_h \) = Hole size, inch

\( D_p \) = Pipe OD, inch

Practical Consideration:

For mudweights below 13 ppg, the yield point of the mud significantly affects the ECD.