r - part - usaid
r - part - usaid
r - part - usaid
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cost of running them, Without additional facilities, a drill<br />
rig has a storage capacity of 756 liters of fuel. At an assumed<br />
rate of consumptian of 300 liters per day while drill.ing (50<br />
likers per hour fur 6 hours), this lasts snfy two and a half<br />
days. In the Bay Region, where distances are nut sa great and<br />
where road conditions are generally better, one fuel truck can<br />
service three rigs, In the Central Range, one fuel truck is<br />
req~ired<br />
for each rig.<br />
The same rationale appzies to the fact that while one water<br />
truck is required for each rig in the Bay Region, two are needed<br />
for each rig in the Central Range, One of these two is based at<br />
the site and used as a stationary starage facility, necessary<br />
because the distance to the nearest water supply may be as far<br />
as seventy-Eivs kilometers.<br />
The equivalent of cne heavy truck is required for each rig<br />
operating in the Bay Region. This represents one knuckle-crane<br />
truck and one flat-bed truck, each shared between two rigs, In<br />
the Central Range the knuckle-crane truck is required to be on<br />
site far the whole time. In most circumstances in the Central<br />
Ra1':ge n flat-bed truck, which is only used to deliver ampplies,<br />
could still be shared between two rigs,<br />
As demonstrated in the BranAon analysis, one obviaus<br />
conclusian fron the above data is that the rate of drilling is<br />
of paramount iaportance. The Groundwater Project has achieved<br />
an overall averzge of 36 working days at each rotary rig<br />
borehole [ap~zaximately 100 borehales in 4 years by 3 rigs).<br />
Not infrequently, however, the drilling crews have completed<br />
their task at the site and moved on within 10 days- The<br />
vzriance about this mean is obviously high. It is not at a11<br />
unusual far WDB drilling crews noh u~>rking an the project to<br />
spend six months or even a f-ll year at one site. In some<br />
cases, this may be the rsault of the slow rate of drilling of<br />
the older cable t asP rigs; it can more often be attributed to<br />
mechanical breakdown or lack of supplies, <strong>part</strong>icularly fuel.<br />
In very simple terms, a rig costing $400,000, with an<br />
expected life of 10 years, drilling 8 boreholes each year,<br />
shouzd charge $5,000 far each borehole for capital recovery<br />
costs. The same rig drilling one borehoie every six months w ill<br />
need to charge $20,000 for each borehole. The answer to this<br />
difficult costing question lies not in desig~ing a costing<br />
system to deal with it, but in maintaining z high drilling rate,<br />
Economies on equipm~gt maintenance and supplies of fuel are, fn<br />
fact, false ecsnoaies.<br />
In a separate calculation, reproduced in Table 2.4.7, the<br />
cost of an idle drilling team operating a production drilling<br />
program in the Bay Region has been calculat-ed at $365 per day.