Page 15 - Oil and Gas Production Handbook An Introduction to Oil and Gas Production

absorb the force of potential
hurricanes. SPARs can be quite
large and are used for water depths
from 300 and up to 3000 meters.
SPAR is not an acronym, but refers
to its likeness to a ship's spar.
SPARs can support dry completion
wells, but are more often used with
subsea wells.
Subsea production systems are
wells located on the sea floor, as
opposed to on the surface. As in a
floating production system, the
petroleum is extracted at the seabed, and can then be 'tied-back' to an
already existing
production platform
or even an onshore
facility, limited by
horizontal distance
or "offset". The well
is drilled by a
moveable rig and
the extracted oil
and natural gas is
transported by undersea pipeline and riser to a processing facility. This
allows one strategically placed production platform to service many wells
over a reasonably large area. Subsea systems are typically in use at depths
of 500 meters or more, and do not have the ability to drill, only to extract and
transport. Drilling and completion is performed from a surface rig. Horizontal
offsets of up to 250 kilometers/150 miles are currently possible. Photo:
StatoilHydro

2.2 Main process sections

We will go through each section in detail in the following chapters. The
summary below is an introductory synopsis of each section

2.2.1 Wellheads

The wellhead sits on top of the actual oil or gas well leading down to the
reservoir. A wellhead may also be an injection well, used to inject water or

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