Introduction to Electrokinetics - Electrokinetics for Petroleum and Environmental Engineers - page 22

equal to 40 meters (Anbah et al., 1965) and substituting the above values
in Eq. 1.13:

.amps

2 *. * * 3 14 3 100

I

= = 31 4

40
01

10 *ln

.

Thus, the power consumption is equal to:

KW

100
1000

31 4 .* = 314 .

The approximate cost of electricity (at $0.059/KW-h) = 3.14 x 24 x 0.059
= $ 4.45 per day per well. If the labor cost is assumed to be $50 per day
per well (Gillette, 2006), then the total cost becomes $54.45 per well per
day. It is assumed that the equipment needed (electronic power supply,
electrodes, power cables, etc.) will cost approximately $55,000 per well. If
the estimated life of the equipment is five years and its salvage value is
11,000, then by using straight-line depreciation at 6 % average interest, the
annual depreciation plus interest is equal to $10,494 per well (modified
after Anbah et al., 1965).
According to laboratory experimental results and the application of
electrokinetics in related engineering field, an average increase in the flow
rate of oil (corresponding to 3.14 KW-h) can be estimated as 13.9 B/D per
well. The annual gross dollar return (at $70/Bbl) is equal to $355,145.00,
and after CMR tax (at $6/Bbl) is equal to $324,704.00. This value minus
the annual labor and electricity cost will give a net annual profit of:
$324,704.00 - $19,874.25 = $304,829.75. The net profit is approximately
equal to 304,829.75/10,494.00 ≈ $29.05 dollar returned per dollar invested
(modified after Anbah et al., 1965).
These rough sample calculations are presented here in order to indicate
the possibility of application of electrokinetics in the field (see Chapter 3).

1.11 Releasing Stuck Drillpipe

As pointed out by Helmick and Longley (1957), stuck drillpipe occurs
when drillstring embeds itself into a layer of filtercake on the borehole wall
(differential sticking). A significant force is required to free the pipe; thus,