Page 216 - Introduction to Petroleum Engineering

ACTIVITIES 203
As noted previously, surface facilities of a well consist of the wellhead, the
Christmas tree, a pump driver, a separator, storage tanks, and pipelines. Pump drivers
were described earlier. The wellhead provides mechanical support for the casing and
tubing and access through valves to annular spaces between successive casing strings
and tubing. The Christmas tree is bolted to the top of the wellhead and is connected
to the tubing. It is used to control fluids produced from the tubing. The Christmas tree
usually splits into two or more branches adorned with valves and pressure gauges.
Oil and gas wells produce oil, water, and gas in varying quantities and ratios. For
example, some gas wells produce gas with a little condensate and some water, while
other gas wells produce a lot of water. Connected to the Christmas tree, separators
must cope with the challenges of separating these fluids. Most separators operate at
100–200 psi and depend on the differences in density among phases to separate the
fluids by gravity segregation. To facilitate separation of oil and water and to prevent
formation of ice and gas hydrates, most separators are heated, especially in cold
weather. Effluent gas from the separator passes through a backpressure regulator that
keeps pressure constant in the separator. Fluid levels in a separator are maintained
with level‐control valves. At least two flow lines leave a separator: one carries gas to
a central gas plant, the other carries liquids. For small rates of liquid flow, the liquids
line goes to storage tanks at the well site. For high liquid rates, the liquids line goes
to a central processing facility. As needed, trucks can unload liquid from storage
tanks on location.

10.7 ACTIVITIES

10.7.1 Further Reading
For more information about completions, see Economides et al. (2013), Hyne (2012),
Denehy (2011), van Dyke (1997), Brooks (1997), Schecter (1992), and McGuire and
Sikora (1960).

10.7.2 True/False
10.1 Skin can be negative or positive with units of feet.
10.2 Skin depends on the depth of penetration of formation damage.

10.3 Production tubing is routinely cemented to the borehole wall.
10.4 Liners extend from the surface down to the depth of the producing formation.
10.5 The number of shots per foot equals the number of shaped charges per foot.
10.6 If Brooks’ N is 40 for a perforation plan, the design can be improved by
pd
selecting shaped charges that will give more penetration.
10.7 Perforating guns are commonly used to punch holes in tubing.
10.8 Acetic acid is used for treatments of silicate minerals.