Operational Experience Using Acoustic Reflectometry to Detect Blockages in Gas Pipelines

Abstract

Abstract This paper will provide an overview of a novel acoustic reflectometry method that has been developed to detect features, such as blockages and leakages in industrial gas-filled pipelines. The basic concept of the technique is to inject a pulse of sound into a pipeline and then measure the reflections produced as this signal travels along the length of the pipe. Wherever the cross sectional area of the pipeline changes, such as points of partial or full blockage, there will be a reflection produced. By measuring these reflections and using knowledge of the speed of sound in the gas, the location of any features in the pipeline can be identified. The technique is non-invasive and can be used remotely to accurately detect many pipeline features, such as holes, blockages and other objects including valves and even girth welds. The paper will present the results from laboratory tests and field trials which will show the accuracy of the technique in detecting and locating blockages and valve status in industrial pipelines containing high pressure gas. In particular details of a test where the method was used to locate an obstruction in a live offshore pipeline containing high pressure will be provided. The difficulties associated with detecting abnormalities in industrial gas pipelines will be discussed and suitable signal processing methods will be described which should enable the technique to be applied as a continuous monitoring tool for offshore gas pipelines.