Page 202 - Drilling Technology in Nontechnical Language

Chapter 8 – DIRECTIONAL AND HORIZONTAL DRILLING 193

Multilateral wells

It is possible to drill a wellbore and, from that “mother” bore, drill
several side bores. Multilateral wells are drilled to greatly increase the
amount of well exposed to the reservoir. This allows more oil or gas to be

produced with lower pressures. As shown in figure 8–11, it can also allow
several small reservoirs to be exploited with a single well, which might
otherwise be uneconomic if several wells were needed.

Fig. 8–11. Multilateral well diagram

Geosteering

For most wells, the objective is to drill along a predetermined well path
to penetrate one or more defined targets. While the well will not follow

the planned well path exactly, it should penetrate each target. However,
some wells may be drilled with reference to downhole characteristics that

are not accurately known before drilling. Take another look at figure 8–1
at the beginning of this chapter. This illustrates an extended reach well

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