Page 419 - Hydrocarbon Exploration and Production Second Edition

406 Infill Drilling

production well

fault

bypassed attic oil
oil

high k
low k

isolated fault
layers

direction of flow

drained undrained
Figure 17.1 Undrained hydrocarbons. original profile

Production Rate (Mstb/b) 20 additional reserves

accelerated reserves
15
reduction due to
previous acceleration
10

5
Time
Incremental
Economic Abandonment Rate
Production Lifetime
Figure 17.2 Additional and accelerated reserves.

may be recovered, though inefficiently in terms of barrels produced per barrel
injected. Drilling an infill well to recover bypassed oil will usually generate extra
reserves as well as some accelerated production (of reserves that would eventually have
been recovered anyway). To decide whether to drill additional wells it is necessary to
estimate both the extra reserves recovered, as well as the value of accelerating existing
reserves (Figure 17.2).
In a completely homogenous unfaulted reservoir, a single well might, in theory,
drain all the reserves, though over a very long period of time. FDPs address the
compromise between well numbers, production profiles, equipment life and the