Method and apparatus for pattern match filtering for real time acoustic pipeline leak detection and location

• US 20020124633A1
• Filed: 05/15/2002
• Published: 09/12/2002
• Est. Priority Date: 05/27/1999
• Status: Active Grant

• Current Assignee: Acoustic Systems Incorporated
• Original Assignee: Acoustic Systems Incorporated
• Inventors: Yang, Bao-Wen, Recane, Marion
• Granted Patent: US 6,668,619 B2
• Time in Patent Office: Days
• US Class Current: 73/40.5R
• CPC Class Codes: G01M 3/243 for pipes

Abstract

A method and apparatus is provided for detecting and locating leaks in a pipeline. Pattern match filtering is used to reduce false alarm rate, increase sensitivity and improve leak location accuracy, while quickly detecting leaks by the acoustic signal generated from a leak event in pipelines containing gas or liquid under pressure. The pattern match filter technique detects a pressure wave generated by a leak, but discriminates against background noise and pressure disturbance generated by other non-leak sources that might otherwise be detected as a leak. The pattern match filter derives a sharp peaked output from the signal of the expansion wave which allows for a distinctive point of reference for a time stamp. This provides for improved accuracy in leak location calculations. The pattern match filter is incorporated into site processors located at multiple points along a pipeline, and at a central node processor which receives data from all site processors. The pattern match filter includes using previously recorded leak profiles. At site processes located at multiple points along a pipeline, a series of previously recorded signature leak profiles are continuously compared in real time against pipeline pressure signals. Data from each site processor are used collectively at a node processor and compared against multiple leak profiles to provide further false alarm rejection. The leak event data generated at each site processor is used by the node processor to declare a leak. By the application of this pattern match filter technique, the signal to noise ratio (S/N ratio) required to identify a leak event is reduced and the sensitivity of leak detection is increased.

Claims

1. An apparatus for detecting leaks in pipelines comprising:

sensor means on the pipeline for sensing fluid pressure in the pipeline;

site processor means interconnected with the sensor means for processing fluid pressure data obtained by the sensor means;

filter means in the site processor means for comparing the processed fluid pressure data with pre-recorded values of fluid pressure data corresponding to leaks in pipelines; and

alarm output means for indicating a leak in the pipeline when the processed fluid data matches the pre-recorded values.

2. The apparatus of claim 1 wherein the processor means receives fluid pressure data from a plurality of pressure sensors.

3. The apparatus of claim 1 wherein the processor means receives fluid pressure data from two pressure sensors.

4. The apparatus of claim 3 further comprising node processor means, the node processor means interconnected with a plurality of site processor means, the node processor means including second filter means for comparing the processed fluid pressure data from a plurality of site processor means with pre-recorded values of fluid pressure data corresponding to leaks in pipelines.

5. The apparatus of claim 4 further comprising means for locating leaks in pipelines comprising time stamp means for recording the time of an acoustic pressure profile at a plurality of sites, and means for calculating location.

6. A method for detecting leaks in pipelines comprising the steps of:

obtaining past fluid pressure data associated with past leaks in pipelines;

sensing fluid pressure in a pipeline at a plurality of locations with fluid pressure sensors;

comparing the sensed data with the past data in a site processor; and

issuing an alarm if the sensed data matches the past data.

7. The method of claim 6 wherein the step of comparing the sensed data with the past data is conducted over a plurality of data points.

8. The method of claim 7 further comprising the step of comparing the sensed data with a plurality of past data from a plurality of site processors in response to an alarm, in a node processor.

9. The method of claim 8 further comprising the step of transmitting the alarm signal from the node processor to a computer terminal when the comparisons from a plurality of site processors indicate the sensed data matches the past data.

10. The method of claim 9 further comprising the step of locating a leak in a pipeline by time stamping data for recording the time of an acoustic pressure profile at a plurality of sites, and calculating the leak location based on the time and the velocity of sound in a fluid in the pipeline.