1. [Drilling] A section of a wellbore, usually openhole, where larger diameter components of the drillstring, such as drillpipe tool joints, drill collars, stabilizers, and the bit, may experience resistance when the driller attempts to pull them through these sections. 2. A well that the operator requires be kept as secret as possible, especially the geologic information. Exploration wells, especially rank wildcats, are often designated as tight. Unfortunately, this designation is of questionable benefit in keeping the data secret.

Drilling a well in which the information obtained is restricted and passed only to those authorized to receive it.

Secrecy surrounding information on well being drilled. Preventing competitors from finding out what has been found.......Usually :-)

A well about which information is restricted and passed only to those authorized, for security and competitive reasons.