# Hydromechanical specific energy

## Input(s)

WOB: Weight on Bit (lbf)

$$\mathrm{A}_{\mathrm{b}}$$: Area of Bit $$\left(\mathrm{ft}^{2}\right)$$

$$\mathrm{N}$$: Rotational Speedfor a Bit $$(\mathrm{ft} / \mathrm{s})$$

$$\eta$$: Factor for Energy Reduction (dimensionless)

$$\mathrm{P}_{\mathrm{b}}$$: Presure Drop Across Bit (psi)

Q: Flow Rate $$\left(\mathrm{ft}^{3} / \mathrm{s}\right)$$

ROP: Rate of Penetration $$(\mathrm{s} / \mathrm{ft})$$

T: Torque (lbf ft)

## Output(s)

HMSE: Hydro Mechanical Specific Energy $$\left(\mathrm{lbf} / \mathrm{ft}^{2}\right)$$

## Formula(s)

$\mathrm{HMSE}=\left(\frac{\mathrm{WOB}}{\mathrm{A}_{\mathrm{b}}}\right)+\left(\frac{120 * 3.142 * \mathrm{~N} * \mathrm{~T}+1154 * \eta * \mathrm{P}_{\mathrm{b}} * \mathrm{Q}}{\mathrm{A}_{\mathrm{b}} * \mathrm{ROP}}\right)$

## Reference(s)

Samuel. E Robello. 501 Solved Problems and Calculations for Drilling Operations. Sigma Quadrant. 2015. Houston, Texas, Page: 415.

## Related

### Mechanical specific energy

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