During drilling operations, some type of a drilling problem will almost certainly occur, even in very carefully planned wells. The reason is that geological conditions for two wells that are near each other may differ (nonhomogeneous formation); therefore, different problems can be encountered.
The key to success in achieving well objectives is to design drilling programs based on anticipation of potential hole problems, rather than on containment and caution. Drilling problems, when encountered, can be very costly, the most prevalent of which are:
Pipe sticking
Lost circulation
Hole deviation
Pipe failures
Borehole instability
Mud contamination
Formation damage
Hole cleaning
Hydrogen sulfide–bearing formations and shallow gas
Equipment- and personnel-related problems
An understanding of these problems, their causes, their anticipation and planning for solutions is essential to control overall well cost control and succeed in reaching the intended target zone. This chapter addresses these problems, possible solutions, and when applicable, preventive measures.