Page 149 - Air and Gas Drilling Manual

approximate fuel consumption rate at this power level is 0.537 lb/hp-hr. The total
weight of diesel fuel consumption per hour is
˙ w = 0 .537 (168 . ) =7 90 .6 lb/hr Chapter 4: Compressors 4-35
f
The specific gravity of diesel fuel is 0.8156, thus, the total volume (in United States
gallons) of diesel fuel consumption per hour is
q = 90 6 . = 13 3 . gal/hr
f
.
(0 8156 )(8 33 )
.
4.7 Example Compressor System Units
In this section four operational example compressor system units are presented.
These units represent the wide variety of units in operation around the US and the
world. In follow-on illustrative examples for air and gas drilling operations, stable
foam drilling operations, and aerated fluid drilling operations, one of these four
compressor system units will be used as the provider of the compressed air or gas.
These compressor system units are a mix of reciprocating compressors and rotary
compressors.
4.7.1 Small Drilling Rig with Integrated Rotary Compressor System
Figure 4-19 shows the portable Tamrock Driltech Model D25K drilling rig.
With certain limitations, the rig is capable of drilling to a depth of about 1,000 ft.
These small single rigs usually use Range 1 (i.e., 18 ft to 22 ft in length) drill pipe.
These small drilling rigs are used for drilling water wells, environmental monitoring
wells, and other geotechnical boreholes. Unlike the larger drilling rigs discussed in
Chapter 1, these smaller drilling rigs are designed with their mud pumps and/or
compressors integrated into the rig deck.
The Tamrock Driltech Model D25K drilling rig is equipped with a Sullair
Model 840, two-stage, oil flooded, helical lobe (screw) rotary primary compressor.
Figure 4-20 shows this compressor standing alone away from the rig. As can be
seen, this rotary compressor is rather small. This emphasizes one of the main
advantages of the rotary compressor. For similar volumetric flow rate capacity
compressors, the size (footprint) of a rotary compressor will be smaller than that of a
reciprocating compressor. The Sullair Model 840 is operated at 1,800 rpm. At this
speed, the compressor has a volumetric flow rate of 840 scfm and produces a fixed
output pressure of 340 psig (at API Mechanical Equipment Standards standard
conditions).
Most small portable single rigs are designed with an integrated on-board air
compressor or mud pump. These air compressors (or mud pumps) are placed on the
rig deck and can be powered by either the portable rig prime mover (via power-take-
off), or by a dedicated stationary prime mover also on the rig deck. The Sullair
Model 840 primary compressor of the Tamrock Driltech Model D25K drilling rig is
powered by a separate prime mover on the rig deck.
The dedicated deck mounted prime mover for the Tamrock Driltech Model
D25K drilling rig is a Caterpillar Model 3406, in-line six cylinder, diesel fueled