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SIDE SCAN AND METAL DETECTOR HELP IN OIL CO COMEBACK

According the US Dept. of Energy and the American Petroleum Institute, hurricanes Katrina and Rita were the worst in the history of Gulf of Mexico oil and gas production, causing unprecedented damage and prolonged evacuations. Many oil and gas facilities are still trying to get back to pre-hurricane operating levels including the Louisiana Offshore Oil Port or LOOP LLC.  The port facility is located in 110 feet of water 18 miles off the Louisiana coast and is jointly owned by Marathon Ashland Pipe Line, Murphy Oil Corp., and Shell Oil.  It is the only port in the US capable of off-loading deep draft tankers known as Ultra Large Crude Carriers (ULCC).

The port consists of three single-point mooring buoys for the off-loading of crude tankers, and a marine terminal consisting of a two-level pumping platform and a three-level control platform.  A 25 mile pipeline connects the port facility to an onshore storage facility.  Four pipelines connect the onshore facility to refineries in Louisiana and along the Gulf Coast.  Oil is also pumped through CAPLINE, a 40 inch diameter pipeline, to several refineries in the Midwest.  In total, LOOP is connected to over 50 percent of the US refinery capacity and has off-loaded over 7 billion barrels of foreign crude oil since its inception.

After the hurricanes, the port facility and supply pipelines required surveying to verify the underwater structures were sound, and to confirm the location of pipelines which sometimes shift in heavy storm surge.  David LeBlanc, an engineer for the company, reported that they had a difficult time hiring a survey firm to perform the needed side scan work.  “After the hurricane the demand for side scan services was so great,  we were told it would be weeks before they could do the job.  When they finally showed up and performed the survey, we were only given a verbal report on the status of our structure and pipelines.  Eventually we were given a rough map of the survey area, but it lacked the kind of detail we were looking for.  At that point we decided to purchase our own equipment and contacted JW Fishers to get more information on the type of equipment that would work best for our application. When we saw the cost of complete system, we were surprised that it was actually considerably less than what we paid for a single survey.”

Two pieces of equipment were selected to meet their requirements; a boat-towed metal detector and a side scan sonar.  In addition to the survey work, one of their other projects was to locate and mark the position of a buried pipeline running from the platform.  Most of the pipelines ran in pretty much a straight line from the port, but one line made a strange loop.  It was extremely important to mark the exact location of the pipe before new pilings could be driven.  The engineers knew a magnetometer wouldn’t be of much help because of the proximity to the large steel structure.  They thought a metal detector might work, but the pipeline had several meters of mud covering it, which would put it out of range for a hand-held model.  The Pulse 12 boat-towed metal detector was recommended by Fishers and  proved to be the right tool for the job with it’s significantly increased detection range.

LOOP’s team decided the best way to use the Pulse 12 for this particular project was to have two divers drag the metal detector’s search coil across the ocean bottom.  They started tracking the pipeline from where it left the platform and entered the bottom.  Knowing where the pipeline started, it was a relatively easy task to track it’s path under the sea floor.  As  the coil was dragged across the bottom the topside crew monitored the metal detector’s control unit and communicated to the divers when they were getting the strongest readings.  “The Pulse 12 worked very well for this project”, reported maintenance support technician Andre Duet.  “We found all kinds of things buried down there; from hand rails that were blown off the platform during storms, to tools that had been dropped over the side.“

Initial tests with the side scan have been extremely promising reports David LeBlanc.  “Working from a small boat in shallow water only a few miles offshore we surveyed an area where we knew the location and condition of several pipelines.  I was amazed at the resolution of the images on the short ranges, you could not only see the lines, but also breaks and cracks in the concrete casings.  We even saw one small pipe running right over the top of another.  The strange thing is that this pipeline wasn’t there before the hurricane.”

With the purchase of the side scan, LOOP engineers can now perform a survey at any time.  In addition to saving ten of thousands of dollars on subcontract work, engineers will also have their own permanent record of the survey area.  According to corporate manager Morgan Wolf, “Sometimes we have an immediate need to get a picture of the bottom.  In this industry the survey providers can not respond that fast.  Having this equipment and being able to do a quick survey at any time, is worth significantly more to us than the investment in this equipment.  We’re very happy to have JW Fishers as our technology partner in this effort.  The company has provided excellent service and support.”