Definition - What does Blind Well mean?
In trenchless construction, blind wells are horizontally constructed wells where drilling and installation take place at one end only. In other words, the ground is penetrated only once at the launch pit. Blind-wells are constructed using horizontal directional drilling techniques whereby a pilot bore is initially drilled, followed by a reamer to enlarge the bore to the required size.
Blind wells are also known as single-entry wells or single entry completions. They are the opposite of double-entry wells.
Trenchlesspedia explains Blind Well
Single-entry wells are commonly used in situations where there is no access to a reception pit or where a specific zone beneath a structure or obstruction needs to be accessed.
Once the pilot hole is drilled, it is enlarged to the required diameter using a series of reamers. Since reaming is carried out by pushing the bit as opposed to pulling it from a reception pit (as is the case in double-entry wells), there is a possibility that the reamer may deviate from the pilot hole. For this reason, double-entry wells are preferred (when possible), since they offer better control of the hole stability.