Performing a Comprehensive Single Pass Multiple Pipeline Survey

This paper presents a discussion of the methodologies and technologies implemented to complete a comprehensive and efficient close interval (CI), depth of cover (DOC) and current attenuation surveys over a new NPS 36 fusion bond epoxy (FBE) coated pipeline influenced by telluric and high frequency AC interference. The DOC and current attenuation survey interval was set to be the same as the CI survey interval (5^′) to facilitate detailed profile of the pipeline, and to identify any area where marginal cover or geometric anomalies may exist. By completing both surveys in one pass, there was assurance that the CI readings were taken over the target pipeline. The DOC survey was completed with a continuous data stream from an electromagnetic pipe locator utilizing omni-directional antenna coils. All survey readings were recorded with highly accurate real time GPS to allow time synchronization and geographic information system (GIS) implementation of the survey data. GPS synchronization of the stationary, mobile data loggers and rectifiers were verified with multiple daily waveform analysis. Rectifiers were fitted with SCADA communications and GPS RMUs for remote monitoring and operation. Telluric and high frequency interferences were compensated for through waveform logging at both stationary data log and the remote surveyor points. Optimal readings were determined through advanced statistical analysis of the survey data.