A novel method for overcoming the problem of pipeline leak detection in India

1. Problems faced by Industries during
PipelineTransportation
Exposures
LeaksEncroachmens
Fire

2. Table 1: Causes of pollution expressed in the study area
expressed in percentage (author-Newcastle University, UK,
2012)
• Sources No of respondents Percentage
well leakage 4 13
• Pipeline related sources 20 67
• Reservoir/tankers related 1 3
• Facility failures/ ageing 5 17

3. Classifying leak detection
technologies
We distinguish them in three categories:
• automated detection - complete monitoring systems that,
can report the detection of a gas leak without the need of
a human operator, once they are installed (e.g. infrared
sensors, fiber optic or cable sensors).
• semi-automated detection - solutions that need a certain
amount of input or help in performing some tasks (e.g.
statistical or digital signal processing methods)
• manual detection - systems and devices that can only
be directly operated by a person (e.g. thermal imagers ).

5. Methods currently used and their
problems
• Low Orbit Satellite Imaging->Off line system : Once per month +
image processing time ,Not effective if clouds present,Under ground
pipeline : Hence nothing visible : Not sure whether we are looking at
the images of land above our pipeline.
• Helicopter Surveillance->In worse weather conditions, helicopter
surveillance becomes impractical,Possibility of human error
• Sonic vibration sensors->Risk of spurious alarms due to movement
of vehicles etc.
• Optical Fibre based monitoring
• Meters are installed at at certain intervals and cumulative is checked
that is net accumulation in a control volume should be zero->not a
continuos method so will take time to detect where is the leakge

6. COMPARISON OF VARIOUS
TECHNOLOGIES
Technology Parameter/ Criteria
Monitoring Additional
equipment
requirement
Procesin
g time
Probabilty
of false
alarms
Maintenan
ce
Cost
Online Sonic
sensors/ Threat
scan
Online Yes Continu
ous
High Required Very
High
Satellite
Imaging
Fixed No Fixed
frequen
cy
No No High
Optical Fibre
based
monitoring
Online Yes Continu
ous
High Required Very
High
Helicopter
monitoring
Fixed
frequency
No Fixed
Frequen
cy
NO No Low

7. The Motivation
• The specific goals of pipeline leak detection include desired
sensitivity, leak detection time, leak location capability, accuracy of
leak volume estimates, and adaptability of a given technology to
routine and non-routine activities.
• The system presently used detects gas leakage but the industries
want it on ppm and ppb level
• For cost cutting linemen are used who use soap solution at joints to
check which is not much reliable.
• As important as detecting a leak is, the controller’s response is
equally critical. There have been several cases where the leak
detection system detected an actual leak and declared an alarm
which was ignored by the controller so shifting to fully automated
rather than manual and semiautomated
• The pipeline leak detection system should be able to detect a leak
as small as 0.5 percent (%) of the daily throughput.

8. Solutions that can be used
• There are internally (observing hydraulic behavior) and externally
(released fluid detection) based(Pipeline Leak Detection) PLD
technologies. Computational pipeline monitoring (CPM) is an
internally based PLD technology CPM uses pressure, flow,
temperature, and/or acoustic instruments to measure single or multi-
phase fluid parameters within a segment of pipeline. A Supervisory
Control and Data Acquisition (SCADA) system monitors,
processes,transmits, and displays the pipeline data to a controller in
a control room. Using computer software programs to analyze the
information and issue an alarm when a leak is detected
• External methods include hydrocarbon vapor or liquid-sensing
devices such as infrared sensors as well as aerial surveillance
along pipeline corridors. chemical sensors, and electrical sensors.

9. What is a good leak Detection
System

10. 10
Pipeline Configurations

11. Real Time Transient Model
Internally-Based System
• RTTM means “Real-Time Transient Model”.RTTM LDS(leak Detection
System) use mathematical models of the flow within a pipeline using basic
physical laws such as conservation of mass, conservation of momentum,
and conservation of energy.
• RTTM methods can be seen as an enhancement of balancing methods as
they additionally use the conservation principle of momentum and energy.
An RTTM makes it possible to calculate mass flow, pressure, density and
temperature at every point along the pipeline in real-time with the help of
mathematical algorithms.
• RTTM LDS can easily model steady-state and transient flow in a pipeline.
Using RTTM technology, leaks can be detected during steady-state and
transient conditions.
• With proper functioning instrumentation, leak rates may be functionally
estimated using available formulas

12. 12
Software Method - RTTM
Advantages
It takes into account the configuration of the pipe as well as the
product characteristics.
Very fast in detection and location
Very less probability that it will produce False Alarms.
Involves computer simulation of pipeline conditions using advanced
fluid mechanics and hydraulic modeling.
Can be used for anykind of Pipeline whether it is Underground or
Overground or small or big.
Measuring purely the flow won’t show up the true leak. RTTM
measures the temperature and pressure at outlet and inlet. A robust
set of algorithms calculates the flow.

13. 13
Software Method – Gradient Intersection
Xleak

14. 14
Simulation Procedure - Leak in Pipe 8
Calculator
Leak induced in Pipe 8
Optimizer

15. 15
Simulation Results- Leak in Pipe 8
Leak Simulated
Pipe 8
Location(m) 450
Magnitude(kg/s) 2.611
Measured Flow 4.946
Measured
Pressure (kPa)
2160.1
Pipe
Functional Values
1 126.678
2 97.438
3 101.864
4 123.710
5 126.447
6 126.447
7 63.294
8 0.151
9 159.922
Estimated
Magnitude(kg/s)
2.609
Estimated
Location(m)
450

16. Analysis of Pipeline Leak Detection
System

17. How calculations are done
Balancing Systems
Uses the principle of mass conservation
Basic equations used in RTTM are:
Continuity equation:
Momentum Equation:
Energy equation:
dt
dM
tMtM L
OI =− )()(
..
0=
∂
∂
+
x
v
dt
d
ρ
ρ
0.
1
=+
∂
∂
+ Df
x
p
dt
dv
ρ
0.
1
=−− Ll
dt
dp
dt
dh
ρ

18. Variables invoved in equation

20. 04-Nov-14
In this model Energy Conservation is not of that
significance because it does not help in leak
detection.
It should be mentioned that this model is only for
the pipeline flow in single phase gas or liquid .
Modelling multiphase flow is much more complex
and accuracy is not sufficient to be used in pipeline
leak detection

21. Practical Test of the Model

24. DIAGNOSING AND LOCATING OF THE LEAKAGE

25. 04-Nov-14

26. 04-Nov-14

27. 04-Nov-14

28. 04-Nov-14

29. • An RTTM module calculates estimates M_i,M_o for mass flow at
inlet and outlet, respectively. This can be done using measurements
for pressure and temperature at inlet (P_i, T_i) and outlet (P_o,
T_o). These estimated mass flows are compared with the measured
mass flows m_i,m_o yielding the residuals x=M_i - m_i and y=M_o
- m_o. These residuals are close to zero if there is no leak;
otherwise the residuals show a characteristic signature. In a next
step, the residuals are subject of a leak signature analysis.

30. Assumptions
• Isothermal pipeline flow
• Newtonian fluid
• Fully Developed Laminar Flow
• Leakage treated as flow through orifice
• Steady State

31. Solution

32. Discharge Coefficient
• The discharge coefficient is the ratio of the actual
discharge to the theoretical discharge, i.e., the ratio of
the mass flow rate at the discharge end of the nozzle to
that of an ideal nozzle which expands an identical
working fluid from the same initial conditions to the same
exit pressures.

34. 34
Software Method – Gradient Intersection
Xleak

36. For a simple horizontal pipeline Pressure drops
linearly if friction factor f and pipe diameter D are
constant along the pipeline and in absence of a leak. If
a leak occurs at leak location x_leak, upstream
pressure drop will increased and downstream
pressure drop will decreased .Practically the
pressure drop can be determined by using double
sensor s1 and s2 with known distance between them
l_12 at upstream and another pair s3 ,s4with distance
l34 at downstream

38. Disadvantages
– It is a complex way of leak detection requires trained personnels
and maintenance
– The RTTM method costs much more than the other methods
– Errors in instrument calibration could raise false alarms
– The accuracy of RTTM is limited by multi-phase flow
measurement accuracy

39. CONCLUSION