This information allows very precise operations of various down-hole tools, including perforation guns.
Casing the bottom of the hole allows the well to be completed without having to worry about reservoir fluids.
It also allows precise selection of where in the formation production will be and to be able to seal off perforations, which are no longer useful or counterproductive, through cementing or straddling.
Other methods of stimulation such as acidizing and proppant fracturing are often required to overcome this damage and bring the well up to its full potential.
However, it may have the effect of damaging the formation due to forced entry of well-bore fluid (mud) into the reservoir.