Page 78 - Well Control for Completions and Interventions

Well Construction and Completion Design 69

Figure 2.2 The five reservoir completion methods.

There are advantages and disadvantages associated with each of the
five main completion types, and these are worth exploring further.

2.2.2 Open hole (barefoot) completions
Open hole completions are fairly common in homogeneous carbonate
(limestone and dolomite) reservoirs, where rock strength is generally high
and drilling induced formation damage can easily be removed with acid
(Fig. 2.3). They are less common in sandstone formations. The main
advantages and disadvantages of open hole (barefoot) completions are
summarized in Table 2.1.

2.2.3 Open hole completions with predrilled and slotted liner
Predrilled and slotted liners are generally used where there is a risk of
gross hole collapse. Using a predrilled or slotted liner also allows isolation
between production zones if the liner is run in combination with
External Casing Packers (ECP), or more commonly nowadays, swell
packers. With a liner in place the deployment of intervention tools
becomes simpler. For example, bridge plugs can be set in the blank pipe
inside a Swell packer to isolate water production from a deeper zone.