Page 280 - Hydrocarbon

Surface Facilities 267

Composition: which describes the proportion of hydrocarbon components (C 1 –C 7+ )
and non-hydrocarbon substances (e.g. nitrogen, carbon dioxide and hydrogen
sulphide) present
Emulsion behaviour: which describes how difficult it will be to separate the liquid
phases
Viscosity and density: which help determine how easily the fluids will move
through the process facility.

If formation water production is expected, a chemical analysis of the water
will also be required. It is good practice to record the details of the methods used
for sampling and analysis in each case so that measurement uncertainties can be
assessed.
In addition to fluid properties, it is important to know how volumes and rates
will change at the wellhead over the life of the well or field. Production profiles
are required for oil, water and gas in order to size facilities, and estimates of
wellhead temperatures and pressures (over time) are used to determine how the
character of the production stream will change. If reservoir pressure support is
planned, details of injected water or gas which may ultimately appear in the well stream
are required.
It is important to put a realistic range of uncertainty on all the information
supplied and, at the feasibility study stage, to include all production scenarios under
consideration. Favoured options are identified during the field development
planning stage as project design becomes firmer. Whilst designing a process for
continuous throughput, engineers must also consider the implications of starting up
and shutting down the process, and whether special precautions and procedures will
be required.

11.1.1.2. Product specification
The end product specification of a process may be defined by a customer (e.g. gas
quality), by transport requirements (e.g. pipeline corrosion protection) or by storage
considerations (e.g. pour point). Product specifications normally do not change, and
one may be expected to deliver within narrow tolerances, though specification can
be subject to negotiation with the customer, for example in gas contracts.
Typical product specification for the oil, gas and water would include value for
the following parameters:

Oil True vapour pressure (TVP), BS&W content, temperature, salinity, hydrogen
sulphide content
Gas Water and hydrocarbon dew point, hydrocarbon composition, contaminants
content, heating value
Water Oil and solids content

Table 11.1 provides some quantitative values for typical product specifications.