Pipeline Potential Leak Detection Technologies: A s sessment and Perspective in the Nigeria Niger Delta Region
1058
over the pipeline by air, land or sea. Use of remotely
piloted aerial patrol drones can provide video or photo-
graphic features for pipeline right of way monitoring.
The use of satellite is also being considered in some
quarters. For pipelines in creeks, swamps and difficult
terrain and where the pipelines run into thousands of
kilometre, in a spaghetti network in mangrove trees and
creeks as in the Nigeria Niger Delta region, this method
becomes almost impossible.
3.3. Fibre Optics Systems
A project was initiated by the US department of Energy,
Office of Fossil Energy in this area in 2001 and the over-
all objective was to develop and demonstrate an optical
fiber intrusion detection device that would prevent out-
side force damage by detecting and alarming when con-
struction equipment is near the pipeline vicinity [16].
The principle used in this project was that when heavy
equipment comes into the right of way, it compresses the
soil and creates vibration which changes the dynamics of
the light and reflects the changes to the source. Field
testing of the basic concept has been proved. However,
according to the report of the project close-out, the sensi-
tivity of the technique needs substantial improvement to
be practiced in the industry [8]. This project was cham-
pion by Gas Technology Institute (GTI).
A similar product developed by Future Fibre Tech-
nology (FFT) differs by sending continuous signal in-
stead of pulse light. Their system has also three sensing
fibre strands instead of one strand used in the GTI pro-
ject. Two fibre strands measure the changes in the mo-
tion, sound or vibration while the third delivers informa-
tion to determine location of the event. This tool is cur-
rently being used in Europe and USA [8]. Both systems
however require the fibre to be installed along and close
vicinity to the pipeline
3.4. The Impressed Alternating Cycle Current
(IACC)
This is a kind of pipeline monitoring method consisting
of impressing electrical signals on the pipe by generating
a time-varying voltage between the pipe and the soil at
periodic locations where pipeline access is available. The
signal voltage between the pipe and ground is monitored
continuously at receiving stations located some distance
away. Third party contact to the pipe that breaks thro ugh
the coating changes the signal received at the receiving
stations. Based on information recently found in pub-
lished studies, it is believed that the operation of IACC
on a pipeline will cause no interference with CP systems
[17]. Initial results on operating pipelines showed that
IACC signals could be successfully propagated over a
distance of 3.5 miles (5.63 km), and that simulated con-
tact can be detected up to a distance of 1.4 miles (2.4
km), depending on the pipeline and soil conditions [17].
This method will allow existing pipelines to be retrofit-
ted for monitoring without excavation because the tech-
nique uses existing cathodic protection (CP) test points.
In addition, the method could be readily applied to new
pipelines.
Huebler, (2002) gave the benefits and drawbacks of
the technologies especially for pipeline right of way in-
trusion detection [10], many of which are presented in
Table 2.
4. Discussion
The application of the acoustic methods in the manner of
the most recent technology may require modifications for
use in submerged steel pipelines and manifolds where
attack or encroachment on a pipeline is not through the
act of “digging or ground breaking”. Verification of per-
formance of the acoustic method in submerged pipeline
is yet to be documented. An experience to trace acoustic
transmission on water pipeline at depth of 12 m suggest
that it would not pose a bigger challenge and may even
prove to be easier than land based pipelines. This ex-
perience conforms to the work of Muggleton and Bren-
nan (2004) on the sound attenuation in plastic pipelines
submerged in water. They found that energy does not, in
fact, radiate into the water and the attenuation is small
compared with that for a pipe buried in soil [18].
In managing the noise level in acoustic methods, it
could be possible to study sound generated from a given
pipeline and identify the anomalies that could occur in
the form of act of digging, cutting, ho t tapping and drill-
ing. And then concentrate on monitoring deviation from
“normal” noise levels as a measure of control. This sug-
gestion is relevant because most of the trunk and trans-
mission pipelines on land are located alongside motor-
able roads from where most noise could be generated.
(Using fibre optics in this scenario would lead to a lot of
noise generation). The oil field stations in the region are
not too distant from each other. The implication is that
the acoustic and alternating current attenuation may be
managed by localising the monitoring system to closest
station as possible and identifying the “normal” condi-
tions.
Pipeline networks in most oilfields in the Niger Delta
of Nigeria are more or less “spaghetti” in swamps and
shallow water. Unfortunately, the networks of pipelines
are often the small flow lines in the range of 4 inch to
8inch running from various points and sometimes cross-
ing each other. Use of acoustics and fibre optics methods
for these small diameter pipelines for detection of in-
tended and unintended damages would be technically
and financially cumbersome. New method or combina-
tions of me t hods wo ul d therefore be req ui red.
C
opyright © 2011 SciRes. JEP