Page 218 - Hydrocarbon Exploration and Production Second Edition

Reservoir Dynamic Behaviour 205

OWC
OWC
Steep Dip Shallow Dip

Figure 9.2 Location of wells for solution gas drive.

P i
Reservoir
Pressure
Produced
Produced
GOR
GOR

P b
Oil Rate

R si

Water Cut
Water Cut
Time (Years)
First Oil RF = 5 - 30%
Figure 9.3 Production pro¢le for solution gas drive reservoir.

As for all production profiles, there are three distinct phases, defined by looking
at the oil production rate (for an oil field). After the first production date, there is a
build-up period, during which the development wells are being drilled and brought
on stream, and its shape is dependent on the drilling schedule. Once the plateau is
reached, the facilities are filled and any extra production potential from the wells is
choked back. The facilities are usually designed for a plateau rate which provides an
optimum offtake from the field, where the optimum is a balance between producing
oil as early as possible and avoiding unfavourable displacement in the reservoir,
caused by producing too fast, and thereby losing UR. Typical production rates
during the plateau period vary between 2 and 5% of the STOIIP per year. Once the
well potential can no longer sustain the plateau oil rate, the decline period begins and