Page 199 - Petroleum Production Engineering, A Computer-Assisted Approach

Guo, Boyun / Computer Assited Petroleum Production Engg 0750682701_chap13 Final Proof page 195 3.1.2007 9:07pm Compositor Name: SJoearun

GAS LIFT 13/195

P d

A
S t b
P c

A
P t p

Figure 13.9 Unbalanced bellow valve at its closed condition.

P d

A b
S t
P c

A
P t p

Figure 13.10 Unbalanced bellow valve at its open condition.

for gas passage and a close control over the spread of a throttling valve are the same as the pressure-operated
characteristics are desirable. It has two ports. The smaller valve except that the entrance port of the valve is
port (control port) is used for opening calculations and choked to drop the casing pressure to tubing pressure by
the large port (power port) is used for gas passage using a tapered stem or seat, which allows the port area to
calculations. The equations derived from unbalanced sense tubing pressure when the valve is open. Unlike
valves are also valid for pilot valves. pressure-operated valves where the casing pressure must
drop to a pressure set by dome pressure and spring for the
13.5.2.2 Throttling Pressure Valve valve to close, a throttling pressure valve will close on a
Throttling pressure valves are also called continuous reduction in tubing pressure with the casing pressure held
flow valves. As shown in Fig. 13.14, the basic elements constant. The equations derived from pressure-operated