Page 277 - Hydrocarbon Exploration and Production Second Edition

264 Subsea vs. Platform Trees

Operating costs for a subsea development will often be higher than for a
platform. For example, replacing a choke on a subsea tree will be at least an order of
magnitude more expensive than it would be on a platform. Flow assurance (making
sure the flowlines do not plug up with scale, wax etc.) may require energy, or
chemicals. The colder sea floor temperatures often make these problems more
severe (Figure 10.32).
Finally, the decommissioning of a subsea development will be different from that
of a fixed platform. Removing a floating production facility will be cheaper than
removing a fixed platform, but decommissioning the wells and subsea equipment
might be substantially higher.