Page 159 - Air and Gas Drilling Manual

Chapter
Five

Shallow Well Drilling Applications

Shallow drilling operations account for the majority of wells drilled and for the
most footage drilled with air and gas drilling technology. Shallow drilling
operations use direct and reverse circulation techniques. The calculation tools
required to adequately plan shallow drilling operations can be reduced to rather
straightforward steps and methods. This chapter outlines these steps and methods
and illustrates their application to typical shallow drilling operations. The objective
of these steps and methods is to allow engineers and scientists to cost effectively
plan their drilling operations and ultimately select their drilling rig, compressor, and
other auxiliary air and gas equipment. The additional benefit of this planning
process is that the data created by the process can later be used to control the drilling
operations as the actual operations progress.
In the examples that follow in this chapter only major friction losses for simple
well geometry will be considered. The change of diameters in the drill string due to
the use of drill collars (where applicable) will be ignored. This simplification is
valid for shallow wells.
5.1 Shallow Well Drilling Planning
Shallow air and gas drilling operations use almost exclusively compressed air as
the drilling fluid. Some recent environmental drilling operations have used oxygen
stripped atmospheric air (inert air) as the drilling gas. In this chapter atmospheric air
will be used as the example drilling gas.
The basic planning steps for a shallow well are as follows:

5-1
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