Advanced drilling systems Page: 4 of 7
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that drilling with these systems cost no more than
drilling with conventional rotary technology. It is
also informative to examine the performance of
conventional drilling technology.
The breakout of the costs incurred in com-
pleting the defined interval with conventional
technology is illustrated in the following figure.
12 1/4-i~nch hnle / A~ ett 4A~~ fet
9 5/8-inch casing to surfa
bits, tripping, and turning
logging, testing, etc.
casing & cement
0 10 20 30 40 50 60 70 80 90 100
Rate of Penetration (fph)
Interval Costs with
Conventional Rotary Technology
The end-of-interval costs (i.e. casing, ce-
ment, logging, testing, etc.) do not vary with
penetration rate. However, the costs of drilling
(bits, tripping, and turning on bottom) vary signifi-
cantly with penetration rate. Most of the systems
and concepts we investigated would affect the
costs of drilling.
Costs and Possible Savings
The performance requirements were devel-
oped under the constraint that the advanced tech-
nology cost no more than current technology in
completing the defined interval. Another approach
would be to estimate savings given a particular
improvement in penetration rate.
In most cases, merely matching current
performance would be insufficient for a system to
achieve commercial success. A system would need
to surpass current performance in order to earn
acceptance in the drilling industry. Based on the
same 4,000-foot drilling interval used previously,
the figure below shows savings in dollars that
could be realized if the penetration rate is doubled
or quintupled while all other factors are held
0 5 10 15 20 25 30 35 40 45 50
Rate of Penetration (fph)
Possible Savings Through
As an example of how to interpret this
figure, consider the possible savings at an ROP of
20 fph. This figure indicates that doubling the
ROP would result in savings of about $70,000,
while quintupling the ROP would yield savings on
the order of $120,000.
The possible savings increases significantly
as penetration rates decrease below fifteen to
twenty feet-per-hour. This region is a particularly
attractive target for systems whose primary advan-
tage is to increase the rate of penetration.
Based on the previous figures and discus-
sion, the greatest opportunity for reducing costs
through improved rock cutting techniques is in
hard-rock drilling. That has been the experience of
people who have attempted to market new tech-
niques for cutting rock.
We took a systems approach to avoid over-
looking some facet of the problem that would
prevent successful deployment of a system; how-
ever, there has been another consequence of the
systems approach: we identified a number of
common problems that run across multiple sys-
tems. The concept of common problems is signifi-
cant in that the solution to one of these could
advance the viability of all the systems cross-cut by
that problem. These common problems include
" Multi-channel conduit,
" Electric conductor downhole,
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Pierce, K. G.; Finger, J. T. & Livesay, B. J. Advanced drilling systems, report, December 1995; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc664531/m1/4/: accessed December 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.