Definition - What does Drilling Blind mean?
Drilling Blind is a form of drilling whereby the fracking fluids do not return to the surface. It is also known as blind drilling. During drilling, fluids are used along with drilling equipment to facilitate easy breaking of the rock formation. When the drilling is continued concurrently with the total lost circulation, the fluids or drilling mud do not come back to the surface. There are many reasons that contribute to a Drilling Blind situation such as formation porosity, deep fractures, improper drilling, and invoked fractures to name a few. A leak off test (LOT) is conducted in order to prevent Drilling Blind.
Petropedia explains Drilling Blind
Drilling Blind is referred to as a drilling phase where the fluids used to ease the drilling process do not find a way back to the surface. In simple terms, it refers to a situation where the drilling fluid gets lost in the rock formation while drilling. Commonly known as blind drilling, this situation arises due to total lost circulation, when the drilling fluids flow through the rock formation and do not revert back. When the drilling engineers continue to drill the rock formation during the total lost circulation, it leads to Drilling Blind. A number of reasons contribute to this condition such as the cavernous or hidden deep fractures in the formation, high permeability of the formation or incorrect drilling.