Method for locating leaks in a fluid pipeline and apparatus therefore

• US 5,272,646 A
• Filed: 04/11/1991
• Issued: 12/21/1993
• Est. Priority Date: 04/11/1991
• Status: Expired due to Fees

• Current Assignee: Farmer Edmund
• Original Assignee: Farmer Edmund
• Inventors: Farmer, Edward J.
• Primary Examiner(s): Teska, Kevin J.
• Application Number:
  US07/684,168
• Time in Patent Office: 985 Days
• Field of Search: 364/509, 364/510, 73/40.5 R, 73/40.5 A, 73/40, 73/49.1, 340/605
• US Class Current: 702/51
• CPC Class Codes: G01M 3/2807 for pipes G01M3/2892, G01M3/30 take precedence
• CPC Class Codes: G01M 3/2815 using pressure measurements

Abstract

A method and apparatus for determining the location of a leak in a fluid containing pipeline. Plural monitoring stations sample fluid flow criteria which change in the presence of a leak. The change in the criteria as a function of a variable such as time will allow extrapolation to discern the location. At each location either pressure or flow rate or both are measured. The measurements occur at regular intervals and a record of fluid flow criteria is created for each monitoring station. The record of each monitoring station is continually transmitted to a central location where a data processor analyzes the records and establishes the leak'"'"'s location. One of three algorithms, or any combination thereof, is used by the data processor to calculate the leak'"'"'s location. Each algorithm is tuned to the specific pipeline to compensate for unique characteristics thereof. An output device communicates the location of the leak to an operator or automatically takes appropriate action in response to the leak.

Claims

1. A method for determining the location of a leakage of a transported fluid from a pipeline, the steps including:

defining one or more monitoring locations along a pipeline, and

monitoring, at one or more of these monitoring locations, one or more physical characteristics of the transported fluid prior to an occurrence of a leak to establish baseline values of these characteristics, and

monitoring the physical characteristics after the occurrence of a leak so that differences between the monitored characteristics before and after the occurrence of a leak are identified, and

collecting data representing the differences in the monitored physical characteristics that occur as a result of the leak, the data including measured values of the physical characteristics and a sequence corresponding to when each physical characteristic was recorded, and

processing the data representing the differences in the monitored physical characteristics that occur as a result of the leak using an algorithm that determines the leak'"'"'s location relative to the monitoring location; and

wherein the monitored physical characteristics are selected from a group including fluid pressure and fluid flow rate.

2. The method of claim 1 in which the algorithm of said processing step is tunable to the pipeline being monitored through the steps of:

observing the location computed of a previous leak on the pipeline using the algorithm, and

determining the actual location of the previous leak on the pipeline, and

adjusting the processing algorithm to correct a computed location of the previous leak thereby adapting the algorithm to the specific characteristics of the pipeline.

3. The method of claim 2 wherein the previous leak is an actual leak of known location.

4. The method of claim 2 wherein the previous leak is a simulated leak of known location.

5. The method of claim 1 in which the difference analyzed by the algorithm is the difference in the speed of response of the monitored pressure and the speed of response of the monitored rate of flow, both observed at the same monitoring location.

6. The method of claim 5 comprising the steps of:

determining the difference in the speeds of the pipeline'"'"'s pressure response and flow rate response to a leak, and

calculating a value for the location of the leak, and

correcting the calculated value to account for the characteristics of the pipeline by;

observing the location computed of a previous leak on the pipeline using the algorithm, and

determining the actual location of the previous leak on the pipeline, and

adjusting the processing algorithm to correct the computed location of the leak thereby adapting the algorithm to the specific characteristics of the pipeline, and

outputting the corrected location of the leak;

whereby the leak is located for efficient repair and cleanup.

7. The method of claim 1 wherein establishing the baseline values and after-leak properties of the monitored characteristics, and the differences between them, utilizes statistical filtering which distinguishes between mere pipeline noise and a change resulting from a leak.

8. The method of claim 7 in which the difference analyzed by the algorithm is the ratio of the difference in the absolute value of the change in the product of pressure and rate of flow at one monitored location to the absolute value of the total change in the product of pressure and rate of flow at that monitored location and a second monitored location, the second location being so positioned that the leak lies between the two monitored locations.

9. The method of claim 8 comprising the steps of:

determining the product of the pressure and the rate of flow at the first monitoring location before the occurrence of a leak, and

determining the product of the pressure and the rate of flow at a second monitoring location before the occurrence of a leak, and

determining the product of the pressure and rate of flow at the first monitoring location after the pipeline'"'"'s response to a leak is complete, and

determining the product of the pressure and rate of flow at the second monitoring location after the pipeline'"'"'s response to a leak is complete, and

calculating the location of the leak as a percentage of the distance between the two monitored locations, and

correcting the calculated value to account for the characteristics of the pipeline, by;

observing the location computed of a leak on the pipeline using the algorithm, and

determining the actual location of the leak on the pipeline, and

adjusting the processing algorithm to correct the computed location the leak thereby adapting the algorithm to the specific characteristics of the pipeline, and

outputting the corrected location;

whereby the leak is easily located for efficient repair and cleanup.

10. The method of claim 7 in which the difference analyzed by the algorithm is the difference in time between sensing of a change in value of a monitored characteristic resulting from a leak at a first monitored location and sensing of a change in value of a monitored characteristic resulting from the leak at a second monitored location.

11. The method of claim 10 comprising the steps of:

determining the time at which a change in value of a monitored characteristic is observed at a monitored point, and

determining the time at which a change in value of a monitored characteristic is observed at a second monitored point, said change occurring because of the leak, and

inputting the distance between the two sensing locations, and

inputting the velocity of sound in the fluid in the pipe, and

computing the location of the leak, and

outputting the computed location of the leak,

whereby the leak is easily located for efficient repair and cleanup.

12. The method of claim 11 wherein the monitored characteristics at the first monitored location and the monitored characteristics at the second monitored location are any combination of characteristics taken from a group consisting of:

fluid pressure, and

fluid rate of flow.

13. A method for determining a location of a leakage from a pipeline, the steps including:

monitoring various physical characteristics of a fluid in the pipeline at one or more monitoring locations, and

creating signals from data representing the physical characteristics of the fluid in the pipeline monitored over time, and

sending the signals from the monitoring locations to a processing location, and

preparing a mathematical algorithm for determining the location of the leakage as a function of the created signals, and

analyzing the signals using the mathematical algorithm to determine the location of the leakage, and

wherein said monitoring includes;

measuring a pressure of the fluid and measuring a flow rate of the fluid; and

wherein said creating step includes;

creating a pressure signal representing fluid pressure and creating a flow rate signal representing fluid flow rate.

14. The pipeline monitoring method of claim 13 wherein said analyzing is done statistically including utilizing multiple floating average values for the data represented by the signals.

15. The pipeline monitoring method of claim 14 wherein said preparing of the algorithm includes:

normalizing the pressure signal and the flow rate signal so that a pre-leak steady state value of both the pressure signal and the flow rate signal is considered zero percent (0%) of transition and a post-leak steady state value of both the pressure signal and the flow rate signal is considered one hundred present (100%) of transition,

opening a valve of known location on the pipeline, thus creating an artificial leak thereat,

determining an elapsed time between when a first of the pressure signal and the flow rate signal to change begins to change from zero percent (0%) of transition and when a second of the pressure signal and the flow rate signal to change reaches a percentage of transition equal to a percentage of transition of the first of the pressure signal and the flow rate signal,

establishing a data set representing both the elapsed time and the location of the leak,

repeating the steps of opening a valve, determining an elapsed time and establishing a data set with a different valve of known location open until a plurality of data sets are established,

fitting a curve to the data sets obtained, and

establishing an equation for the curve where leak location is a function of the elapsed time.

16. The pipeline monitoring method of claim 15 wherein said analyzing further includes:

normalizing a pressure signal and a flow rate signal corresponding to an unknown leak so that a pre-leak steady state value of the signals is considered zero percent (0%) and a post-leak steady state value of the signals is considered one hundred percent (100%),

determining an elapsed time from when the first of the pressure signal and the flow rate signal to change begins to change from 0% and when the second of the pressure signal and the flow rate signal to change reaches the same percentage of transition as the first of the pressure signal and the flow rate signal,

inserting the elapsed time into the equation, and

outputting a leak location.

17. The pipeline monitoring method of claim 14 wherein said preparing of the algorithm includes:

measuring a hydraulic length of the pipeline between two monitoring locations,

establishing an equation for leak location by multiplying the hydraulic length by a ratio of a change in fluid horsepower at a first monitoring location to a sum of changes in fluid horsepower at the first monitoring location and a second monitoring location.

18. The pipeline monitoring method of claim 17 wherein said analyzing includes:

determining a pre-leak fluid horsepower at the first monitoring location and determining a pre-leak fluid horsepower at the second monitoring location,

determining a post-leak fluid horsepower at the first monitoring location and determining a post-leak fluid horsepower at a second monitoring location,

calculating the change in fluid horsepower at the first monitoring location and calculating the change in the fluid horsepower at the second monitoring location,

inserting the calculated changes in fluid horsepower into the equation established in said establishing step, and

outputting a distance from the first monitoring location to the leak.

19. The pipeline monitoring method of claim 14 wherein said preparing of the algorithm including:

measuring a hydraulic length of the pipeline between two monitoring locations,

measuring a velocity of sound in the fluid contained in the pipeline, and

establishing an equation for leak location by adding a product of the velocity of sound in the pipeline and a difference in time between when the first monitoring location and the second monitoring location initially receive a signal corresponding to detection of a leak to the hydraulic length and dividing by two (2).

20. The pipeline monitoring method of claim 19 wherein said analyzing includes:

determining when a leak has been sensed at the first monitoring location,

determining when a leak has been sensed at the second monitoring location,

measuring a difference between these two times,

inputting the difference into the equation, and

outputting a distance from the first monitoring location to the leak.

21. An apparatus for determining the location of a leakage of fluid from a pipeline which comprises:

a plurality of means for monitoring physical characteristics of the fluid in the pipeline, and

a means for collecting, organizing, and communicating data obtained by the monitoring means, and

a means for determining the location of the leakage, and

an output device for communicating information relating to the location of the leakage, and

wherein said plurality of monitoring means measure the pressure of the fluid and the flow rate of the fluid at stations along said pipeline.

22. The leak locating device of claim 21 wherein said output device is a display having means to relay information relating to the leak'"'"'s location to a human operator.

23. The leak location device of claim 21 wherein said means for communicating said data collected is a phone modem system, whereby existing phone lines are utilized to transport said data collected from said stations along said pipeline to a common location where said means for determining the location of the leakage analyzes said data.

24. The leak locating device of claim 23 wherein said means for collecting and organizing said created data is a remote terminal unit which coordinates each pressure reading and each flow rate reading at each station with a corresponding time, thereafter repeating this collection process at a new time to continuously update a record of pressure and flow rate thus created.

25. The leak locating device of claim 24 wherein said output device includes an automatic control system connected to said pipeline for diverting flow or shutting off various valves on said pipeline.

26. The leak locating device of claim 25 wherein said collecting and organizing means is a digital computer.

27. The leak locating device of claim 25 wherein said collecting and organizing means is an analog computer.

28. The leak locating device of claim 25 wherein said collecting and organizing means is a collection of discrete electronic or pneumatic components.

29. A kit for attachment to an existing fluid pipeline which enables operators of the pipeline to detect locations of leaks occurring in the pipeline, said kit including:

a plurality of monitoring station pipeline interfaces including means to measure various properties of the fluid within the pipeline and means to collect and sequence measurements taken by said measuring means,

a central data processing station containing means to determine a pipeline'"'"'s leak location from said measurements and means to communicate this information to an operator, and

a communication system including means to transport said measurements from said monitoring stations pipeline interfaces to said central data processing station, and

wherein each of said monitoring stations includes means to measure both a pressure and a flow rate of the fluid within the pipeline, and wherein fluid data thus collected representing the pressure and the flow rate is transformed into an electronic signal;

whereby said fluid data is utilized by said central processing station;

whereby a pipeline'"'"'s performance is enhanced by utilization of said kit thereon.

30. The leak locating kit of claim 29 wherein said central data processing station includes a computer containing an algorithm which determines the location of a leak within the pipeline from the data received from said monitoring stations.

31. The leak locating kit of claim 30 wherein said communication system includes a transmitter at each of said monitoring station pipeline interfaces and a receiver at said central data processing station, whereby data created at each of said monitoring stations may be transmitted to said central data processing station.

32. A system for conveying various fluids and determining the occurrence and location of a leakage of said fluids thereby enhancing safety, minimizing disruptions in normal operation due to leakages, and facilitating rapid leakage damage mitigation, repair, and cleanup, said system comprising in combination:

a hollow conduit for transporting said fluid, and

a plurality of fluid characteristic monitoring means for monitoring the characteristics of the fluid in the conduit, and providing output signals proportional to the characteristics being monitored, and

a leak detection algorithm, and

a leak location algorithm, said leak location algorithm having means to compare said output signals before detection of a leak with said output signals after detection of a leak, and

an algorithm processing means receiving the output from the monitoring means and performing an analysis to determine the existence and location of a leakage,

whereby said system safely, reliably, and efficiently transports fluids.

33. The pipeline of claim 32 wherein said plurality of monitoring means are gauges which measure pressure and flow rate of said fluid.

34. The pipeline of claim 33 wherein said monitoring means further includes a digital computer receiving as input pressure and flow rate data of the fluid at various points along said conduit and outputting to an operator the location of the leak.

35. A method for analyzing measurements of physical characteristics of a fluid within a pipeline to determine the existence and location of a leak in the pipeline, comprising the steps of:

monitoring a plurality of physical characteristics of the fluid which change in response to a leak in the pipeline, before a leak exists, at a plurality of separate locations along the pipeline;

establishing baseline values for the physical characteristics, the baseline values corresponding to the absence of a leak;

collecting data representing changes in the monitored physical characteristics that occur as a result of the leak, the data including measured values of the physical characteristics and a sequence corresponding to when each physical characteristic was recorded;

analyzing the data to detect non-baseline values for the data by utilizing statistical filtering which distinguishes between mere pipeline noise and a variation in values resulting from a leak;

recording an amount of time between which two or more of the separate locations first detect non-baseline values for the physical characteristics; and

determining an arithmetic value representative of the location of the leak by inputting into an algorithm the amount of time recorded in said recording step, a speed of sound in the fluid and a distance between the separate locations.

36. A method for analyzing measurements of physical characteristics of a fluid within a pipeline to determine the location of a leak in the pipeline, comprising the steps of:

monitoring a pressure of the fluid and a flow rate of the fluid at a plurality of separate locations along the pipeline before a leak exists;

establishing initial values for the pressure of the fluid and the flow rate of the fluid at each location, each of the initial values corresponding to the absence of a leak;

calculating an initial value for fluid horsepower of the fluid at each location from initial values for the pressure of the fluid and the flow rate of the fluid at each location;

detecting a leak;

collecting data representing changes in values of the pressure of the fluid and the flow rate of the fluid that occur as a result of the leak, the data including measured values of the pressure and the flow rate and a sequence corresponding to when each value was recorded;

calculating a post-leak value for fluid horsepower of the fluid at each location from the data;

calculating a change in fluid horsepower of the fluid between the initial values calculated and post-leak values calculated at each location; and

determining an arithmetic value of the location of the leak by inputting into an algorithm the changes in fluid horsepower calculated at each location and a distance between the separate locations.

37. A method for analyzing measurements of physical characteristics of a fluid within a pipeline to determine the location of a leak in the pipeline, comprising the steps of:

monitoring a pressure of the fluid and a flow rate of the fluid on a periodic basis beginning before a leak exists, at a single location along the pipeline;

establishing baseline values for the pressure of the fluid and the flow rate of the fluid, the baseline values corresponding to the absence of a leak;

causing an event having an effect on fluid pressure and fluid flow rate similar to an effect of a leak by mimicking disruption of the fluid in the pipeline in a manner affecting fluid pressure and fluid flow rate, the event having a known location along the pipeline;

monitoring a fluid pressure reaction and a fluid flow rate reaction to the event;

calculating a time corresponding to a phase difference between the fluid pressure reaction to the event and the fluid flow rate reaction to the event;

establishing an equation for leak location as a function of time from the time and event location encountered in said causing step and said calculating step;

detecting a leak;

collecting data representing differences in the fluid pressure and fluid flow rate that occur as a result of the leak, the data including measured values of the fluid pressure and fluid flow rate and a sequence corresponding to when each value was recorded;

calculating a time corresponding to a phase difference between a fluid pressure reaction to the leak and a fluid flow rate reaction to the leak; and

determining an arithmetic value of the location of the leak by inputting into the equation the time corresponding to a phase difference between the fluid pressure reaction to the leak and the fluid flow rate reaction to the leak.