Successful Pipeline Inspection

In the summer of 2009, C & C employed the PROSAS to evaluate potential unsupported sections of pipelines on the seafloor, typically called "spans," resulting from marine traffic, tidal scour, and storm impact and to determine whether structural repairs were required. Recently mobilised aboard the 136-foot utility support vessel Andrew Charles, the PROSAS Surveyor performed a two-day 24/7 mission acquiring sonar data with one square inch resolution at 150 metres range per side.

The system produced high-definition, photographic-quality, real-time acoustic imagery across the entire transmission range precluding the typical necessity to run many perpendicular survey lines. This enabled C & C to complete a faster, more cost-effective pipeline inspection survey and reduced the amount of time required for geologists to interpret the pipeline images. The level of detail produced by PROSAS Surveyor enabled the customer to evaluate critical spans in the pipeline structure and to pinpoint the exact location for necessary structural repairs, thereby mitigating the need for significant dive operation costs.

Thomas Chance, president of C & C, said, "C & C is pleased to be alongside AST at the forefront of establishing synthetic aperture sonar as an effective tool for conducting pipeline surveys in the Gulf of Mexico. The advantages of the superior resolution and the consistency of the data have provided tangible results to our customer in the critical area of assessing the condition of spans and exposed subsea pipelines."

Dr. John F. Pesaturo, vice president of AST's Sensor Systems Division, said, "The fact that we have been invited back to perform additional surveys in the Gulf of Mexico further validates our SAS technology as a reliable product that provides tremendous value to the end client. AST is once again pleased with the accuracy and expedience with which our PROSAS Surveyor performed. The key differentiator of SAS technology in this latest survey was its ability to image so accurately on the initial parallel pass that running perpendicular passes on the pipelines, the normal survey approach using traditional side scan systems, added no benefit to the overall picture. This, in turn, saved the client significant survey time and subsequent costs."