ABSTRACT

In this paper, data analytics techniques are used to combine the high spatial resolution measurements from a CIS (close interval survey) with year-round, once daily RMU (remote monitoring unit) measurements from nearby coupons. Up to five years of RMU measurements have been analyzed. The historic trends from various RMU coupon readings are compared with CIS measurements to confirm the validity of the CIS readings, to highlight any high-risk locations on the pipeline and to learn more about the influence of CP rectifiers at various distances along the pipeline. The spatial profile of the CIS measurements between a segment bookended by two coupon RMUs are projected forward in time by using the RMU readings as anchor points on the profile. This can be done in two ways, either by using a specific date's RMU measurements or by fitting a seasonality model to predict how the potential profile could change into the future.

INTRODUCTION

Close interval surveys (CIS) and remote monitoring units (RMUs) can be used as complimentary technologies, essential for validating safe operation of a cathodic protection (CP) system. CIS on a pipeline is typically performed once every few years due to the high cost and time commitment of the process, but the benefit is a high spatial resolution of measurements, with typical spacings between reading locations on the metre length-scale.1,2,3 RMUs installed at test posts with a typical spacing of multiple kilometres between units can be used to measure comparable electrical readings year-round without requiring a human to physically travel to each location.

Supplementing CIS measurements with RMU readings is becoming common practice in the cathodic protection industry.4 Often CIS and RMU are considered separately. We present various methods of combining these two data sources and unlocking new insights which have not been readily available in the past. We will help pipeline operators gain better understanding of their CP systems by sharing these techniques, methodologies and interpretation of results.

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