Page 76 - Petroleum Production Engineering, A Computer-Assisted Approach

Guo, Boyun / Petroleum Production Engineering, A Computer-Assisted Approach 0750682701_chap05 Final Proof page 67 21.12.2006 2:02pm

CHOKE PERFORMANCE 5/67
5.2 A well is producing at 200 stb/d of liquid along with a 5.6 For the following given data, estimate downstream
900 scf/stb of gas. If the beam size is ½ in., assuming gas pressure at choke:
sonic flow, calculate the flowing wellhead pressure
using Gilbert’s formula.
5.3 A 0.65 specific gravity gas flows from a 2-in. pipe Upstream pressure: 620 psia
through a 1-in. orifice-type choke. The upstream Choke size: 32 ⁄ 64 in.
1
pressure and temperature are 850 psia and 85 8F, Flowline ID: 2 in.
respectively. The downstream pressure is 210 psia Gas production rate: 2,200 Mscf/d
(measured 2 ft from the orifice). The gas-specific Gas-specific gravity: 0.65 1 for air
heat ratio is 1.3. (a) What is the expected daily flow Gas-specific heat ratio: 1.3
rate? (b) Does heating need to be applied to ensure Upstream temperature: 120 8F
that the frost does not clog the orifice? (c) What is the Choke discharge coefficient: 0.96
expected pressure at the orifice outlet?
5.4 A 0.70 specific gravity natural gas flows from a 2-in.
pipe through a 1.5-in. nozzle-type choke. The up-
stream pressure and temperature are 120 psia and
75 8F, respectively. The downstream pressure is 5.7 For the following given data, assuming subsonic flow,
90 psia (measured 2 ft from the nozzle). The gas- estimate liquid and gas production rate:
specific heat ratio is 1.25. (a) What is the expected
daily flow rate? (b) Is icing a potential problem? (c) 1
What is the expected pressure at the nozzle outlet? Choke diameter: 32 ⁄ 64 in.
5.5 For the following given data, estimate upstream gas Discharge coefficient: 0.85
pressure at choke: Downstream pressure: 60 psia
Upstream pressure: 90 psia
Upstream temperature: 120 8F
Downstream temperature: 30 8F
Downstream pressure: 350 psia
1
Choke size: 32 ⁄ 64 in. Free gas quality: 0.001 mass fraction
Flowline ID: 2 in. Liquid-specific gravity: 0.85 water ¼ 1
Gas production rate: 4,000 Mscf/d Gas-specific gravity: 0.75 air ¼ 1
Gas-specific gravity: 0.70 1 for air Specific heat of gas at 0.24
Gas-specific heat ratio: 1.25 constant pressure:
Upstream temperature: 100 8F Specific heat of gas at 0.171429
Choke discharge coefficient: 0.95 constant volume:
Specific heat of liquid: 0.8