Page 51 - Air and Gas Drilling Manual

Chapter
Two

Surface Equipment

Air and gas drilling operations require some special surface equipment not
normally used in rotary mud drilling operations. Shallow drilling operations
usually have this specialized equipment incorporated into the single rotary drilling
rig design. For the deeper drilling operations that use double and triple rotary
drilling rigs, this specialized surface equipment is usually provided by an air and gas
drilling equipment contractor. These contractors supply the rotary drilling contractor
(the drilling rig) with the necessary surface equipment to convert the mud drilling rig
to an air and gas drilling rig. The rotary drilling contractor and the air and gas
drilling contractor are usually contracted by an operating company.

2.1 Drilling Location
Nearly all air and gas drilling operations are land operations. Figure 2-1 shows
a typical air drilling location plan for the drilling rig and the other important surface
equipment [1]. The plan in this figure shows the location of the drilling rig
(borehole directly below the rotary table). This is a typical triple drilling rig
configuration. The drilling rig floor is larger and, therefore, it is easier to show the
important features of an air drilling operation with this type of rig. This rig is a
typical mud rotary drilling rig that has been set up to drill with compressed air as
the circulating fluid. The rig is powered by two prime movers on the rig floor.
These prime movers provide their power to the rig equipment through the compound
(a chain drive transmission system). The prime mover on a triple rotary drilling rig
like that shown in Figure 2-1 is limited to operating either the rotary table or the

2-1
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