A viable surface well site needs to be found before a well path can be designed. A detailed geological subsurface prognosis is made based on this design. Special attention is paid to possible drilling hazards such as shallow gas horizons, abnormal formation pressures or soil stability. The well then is designed to handle each particular geological situation.
During the drilling phase, the recovered rock sample (cuttings) descriptions, the gas detection records and the drilling parameters are captured in a mudlog. Technical operations monitors this data continuously in order to quickly react when the prognosis differs from the actual picture.