Rotary Drilling Rig

Hoisting system

Rotary drilling rig

To estimate rotary torque before actual drilling, an empirical relation is used,

HPR = FN

F = Torque factor dependent on the drill string weight and Weight on Bit (WOB)

N= Rotary speed in rpm.

F= 1.5 for shallow holes < 10,000 ft.

1.75 for 10,000- 15000 ft.

2.0 for deep holes with heavy drill strings.

Circulating SystemMain functions:

1. Control subsurface pressures

2. Keep the hole walls from collapsing

3. Remove cuttings from the hole

4. Transmit hydraulic horsepower to the bit

5. Provide information about the formation penetrated

6. Clean ,cool and lubricate the bit.

Its many functions are similar to the purposes of mud system since the functions are controlled by fluid constituents.

Mud pumps:1. Duplex positive displacement pumps

2. Triplex positive displacement pumps

For a duplex double acting pump, the volumetric output is calculated by:

VD= volumetric displacement, gal/stroke

Ls=stroke length,in.

dL=liner diameter,in

Dr=rod diameter,in

Ep=pump volumetric efficiency,%