Comparison of Current Measurements from Oceanographic Mooring and Unmanned Surface Vehicle

Abstract

Monitoring of currents is of high importance for Oil and Gas industry, especially when it comes to design, offload and support to operations. Various monitoring techniques, existing nowadays, with each having their own pros and cons, are briefly discussed in the paper. The objective of study was to compare current data acquired by Unmanned Surface Vehicle (USV), used offshore South America East Coast to support seismic acquisition survey in 2013, to the ones measured by conventional oceanographic mooring (COM) deployed in the same area. Consistency of these datasets was investigated. Efficiency, flexibility and applicability of "static" (mooring) versus "dynamic"(USV) solution for current monitoring applications are discussed. Data analysis started with plotting time series of current speed at selected depth levels. The quick comparison made it possible to discuss data comparability and current speed and direction patterns. The analysis was followed by establishing scatter diagrams, directional distributions and Quantiles-Quantiles plots, which in turn made it possible to conclude on overall data representation, consistency and agreement. USV are relatively new in Oil and Gas industry. Its advantageous feature of being a lowcost, autonomous and quite flexible solution makes them extremely promising for applications in the industry. Positive results from a comprehensive statistical comparison of the datasets showed that it is possible to accurately collect the current data by means of USV, meaning that USV can be considered alternative to conventional oceanographic mooring. Some recommendations on suitable use of each of the techniques are provided following the conclutions from the study.