For natural gas pipelines, it is important to monitor and locate corrosion incidents along the long-distance pipelines. This is especially true for internal corrosion, as it is more challenging to access the inside of the pipes. Distributed optical fiber-based sensors (DOFS) provide unique advantages for natural gas pipeline monitoring. These advantages include long-distance distributed monitoring, flexibility, small size, and improved safety compared to electrical-based sensors in flammable gases. This makes DOFS promising for early corrosion detection. Previously, we have demonstrated DOFS are capable of humidity/water and corrosion sensing inside pressurized tubing in the lab. Here, we report the pilot-scale demonstration of DOFS inside an operating high-pressure natural gas pipeline for distributed measurements along the pipe. Using an optical backscatter reflectometer, the multi-parameter DOFS was demonstrated in a natural gasflowing pipeline (up to 1000 psi, 15 ft/sec flow rate) for monitoring humidity, pressure, temperature, etc. Compared to most studies of DOFS outside the pipe, this is the first demonstration of DOFS inside a natural gas pipeline.
Internal corrosion is a serious concern for the oil and natural gas pipeline industry, and it can negatively impact the integrity of infrastructure necessary for production, transportation, and storage of these volatile energy media. The natural gas delivery system in the U.S. includes 528,000 km (328,000 miles) of transmission and gathering pipelines1. Over the past 30 years, corrosion has caused ∼25% of incidents in natural gas transmission and gathering pipelines, and 61% of these incidents related to corrosion were caused by internal corrosion2.
It is of significant importance to monitor and locate corrosion onset over long-distance natural gas pipelines, especially for internal corrosion. However, it has been challenging to monitor internal corrosion effectively as the inside of the pipeline is not readily accessible during regular maintenance and inspection. Moreover, corrosion tends to be a localized phenomenon that can occur at random locations while pipelines extend for thousands of miles. Locating corrosive spots or localized corrosion can facilitate further inspection and effective mitigation of corrosion before catastrophic failures occur.
