Field Experimental Research on Application of Strain Special Optical Cable and Parallel Optical Cable

Abstract

With the rapid development of China’s oil and gas pipeline mileage, pipeline construction will be unable to avoid crossing high-risk areas such as disaster risk areas, densely populated areas, environmentally sensitive areas. The traditional extensive pipeline patrol method has been unable to meet the requirements of fine management, which puts forward a new test for the upgrade of safety monitoring technology. In this paper, the distributed optical fiber sensing technology which has been studied intensively in recent years is introduced. Through in-depth analysis of pipeline requirements and characteristics of accompanying optical cable, a single-end BOTDA solution suitable for long-distance oil and gas pipelines is proposed. A 400-meter pipeline trench was excavated along the route of a domestic product oil pipeline. Strain special cables and GYTA53 cables were laid concurrently. Twelve strain monitoring sections were set up using vibrating wire strain sensors. The strain of two kinds of optical cables was monitored under various working conditions, such as partial backfilling, full backfilling, manual compaction and heavy mechanical compaction, as well as the monitoring values of two kinds of optical cable for soil temperature. The test results show that: 1) the strain-sensitive fiber optic cable is sensitive to strain feedback, and can produce rapid feedback to 2m3 pile soil, while the stress feedback of pipeline-accompanying fiber optic cable to soil is very small. 2) The temperature around the pipeline can be accurately reflected by the fiber optic cable, and it can be used for temperature compensation in strain monitoring.