Page 95 - Drilling Technology in Nontechnical Language

86 Drilling Technology in Nontechnical Language Second Edition

The example well will drill a horizontal wellbore in a reservoir

containing oil, water, and gas so as to efficiently produce oil.
Concepts from the first three chapters will be referred to but not

explained again. New concepts specific to the type of well and rig under
discussion will be introduced and explained.

Well Planning

In modern developments, wells positioned horizontally in the reservoir
are becoming fairly common. This gives some advantages over vertical
wells, as will be discussed later.
As each well is drilled, it will be left with a special cap on top at the
seabed, called a suspension cap. This protects the wellhead from debris
and corrosion until the platform is in position over the template. With the
platform placed on the template, the wells can be connected and produced.
Coring is not often called for in development wells, but if there is some
remaining uncertainty, it might be required. The logging program will
also be less extensive (and less expensive) than in an exploration well.
At the seabed, all of the wells are close together. The wellbores need
to be positioned in the reservoir some distance apart, which means that
the wells must be drilled directionally to different places in the reservoir
(fig. 4–2).

Completion design

The completion design for a development well must ensure that

the well can be produced safely, efficiently, and economically. The
production engineers will consider various aspects of producing the well
when designing the completion. In particular, attention will be paid to
the following:

1. The well inflow configuration. This affects how hydrocarbons
flow from the reservoir into the well. Sometimes it is necessary

to pressurize the well so as to create fractures in the reservoir,
increasing permeability towards the wellbore. Acid might be used
to create channels in the rock and increase permeability around
the wellbore. These activities are termed stimulation.

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