Page 213 - Hydrocarbon

200 Practical Aspects of Appraisal

of re-using an appraisal well by later installing a subsea wellhead, a tie-back flowline
and a riser may be comparable with that of drilling a new well.
In locations where the addition of facilities for production is relatively cheap,
phased development of a field may be an option. Instead of reducing the uncertainty to
optimise the development plan before development starts, appraisal and develop-
ment may be performed simultaneously. The results of appraisal during the early
development are used to determine the next part of the development plan. This has
the advantage of combining the data gathering with early production, which
considerably helps the cashflow of a project. Phased development with simultaneous
appraisal is more appropriate in onshore and shallow water developments, where
facilities costs are lower. In deep water offshore developments, using single
integrated drilling and production platforms, there is a much stronger incentive to
get the facilities design correct at an early stage, since later additions and
modifications are much more expensive.