Hi Pilko I can answer your question with limited knowledge on...

Hi Pilko I can answer your question with limited knowledge on the number of times a tool gets stuck down the well. It is quite a common occurrence given how large an issue it can create. I have been working in the oil and gas sector although not directly involved in the drilling side of things and I can remember at least half a dozen times in the last 5 years that they have either got a tool stuck or are fishing for a tool. Bearing in mind I am only at work half the time you could double that number.
In fact we are mobilising pipe as we speak because they have lost a tool down the well and are now fishing for it. This is with the 'majors' and offshore so no expense is spared when it comes to equipment and personnel.
Would love Kiwi to elaborate on or correct me but running casing and then perforating it without having the complete data would be a very expensive and impractical stab in the dark without knowing what hydrocarbons you are dealing with. Not to mention the safety and environmental factors involved whilst dealing with an unknown substance.