Open Hole Completion
The casing is placed in the open hole completion type and cemented above the productive interval(s). Further drilling extends the well bore into and/or through the reservoir(s) left uncased, hence the term 'Open Hole'; See Figure below.

Figure 1

All open-hole completions avoid the cost and complexity of perforating but have their complications.

Advantages

This type of completion is standard and find application in competent formations such as dolomite & limestones.
https://www.drillingmanual.com/open-hole-completion/