Page 476 - Offshore Electrical Engineering Manual

Oil Company Operations 463

Where tanker offloading is carried out, a separate floating tanker loading facil-
ity is necessary, as it would be highly dangerous for the tanker to approach within
normal flexible pipe loading distance of the production platform. These single buoy
moorings may have their own storage and pumping facilities and are connected to the
associated platform via subsea pipelines.

ARTIFICIAL LIFT FACILITIES

The output from a typical oil field will rise to a maximum after all the production
wells have been completed. There will then be a plateau in the output figures for,
hopefully, a number of years before outputs start to decline. The timescales involved
vary greatly with different fields and even with different wells in the same field,
particularly where a lot of deviation drilling has been necessary. In order to maintain
the oil output, submersible downhole pumps may be inserted down wells, or gas may
be injected and released low down in the well to reduce the density of the oil. Both
methods tend to increase oil flow rates and are known collectively as artificial lift
facilities.

A.4 OIL COMPANY OPERATIONS
FINANCING
As the cost of recovering oil from a field in the North Sea, from exploration to pro-
duction can easily exceed several £1000 million, it is usually necessary for several oil
companies and financial institutions to collaborate in the project. Typical costs and
employee requirements are shown in Table A.4.1.
It should be noted that the decline in output may be arrested or at least
slowed by the use of artificial lift facilities. As the average cost of drilling a
single exploration well is £3 million, a large part of £100 million may be spent on
exploring a potential field before a decision is made to go ahead with the produc-
tion facility.

DIVISION OF LABOUR
When working on oil company projects, it is particularly necessary to be aware of
the company management structure with respect to project funding and therefore it
is mentioned briefly here.
Most oil companies have four main management streams: operations, mainte-
nance, projects and technical facilities. Those who take responsibility for the produc-
tion plant, the asset holders, are the operators. The maintenance department may be
refused access to an item of plant due for maintenance if it is still required by the
operations department to maintain full oil production.