Hoisting System

1
Hoisting System

• 1.3.3-1

2
1.3.3-2
T

W
W W

• FIG 1-1 Simple Pulley System

T W LD 2W (no friction in sheave)
3
1.3.3-3
n number of lines
W weight (hook load)
LD load on derrick

• FIG 1-2 Block and Tackle System

Assuming no friction
W 4 T T W/4 LD 6 T 6 W/4
4
1.3.3-4 Example 1.1(no friction)

• The total weight of 9,000 ft of 9 5/8-inch
  casing for a deep well is determined to be
  400,000 lbs. Since this will be the heaviest
  casing string run, the maximum mast load must be
  calculated. Assuming that 10 lines run between
  the crown and the traveling blocks and neglecting
  buoyancy effects, calculate the maximum load.

5
1.3.3-5 Solution

• The tension, T, will be distributed equally
  between the 10 lines. Therefore,
• T 400,000/10 40,000 lbf
• The tension in the fast line and dead line will
  also be 40,000 lbf, so the total load is
• 40,000 X 12 480,000 lbf

6
1.3.3-6 Solution, cont.

• Example 1.1 demonstrates two additional points.
• 1. The marginal decrease in mast load
  decreases with additional lines.
• 2. The total mast load is always greater
  than the load being lifted.

7
1.3.3-7
A Rotary Rig Hoisting System
8
1.3.3-8
Projection of Drilling Lines on Rig Floor
TOTAL
9
1.3.3-9 Load on Derrick(considering friction in
sheaves)

• Derrick Load Hook Load
• Fast Line Load
• Dead Line Load
• Fd W Ff Fs

E overall efficiency, e.g., E en 0.98n
10
1.3.4-1 Rig Power

• Mechanical (Power)
• Diesel Electric
• Electric