This paper describes the method and equipment developed to allow ROV installation of a grout-filled reinforcement sleeve on a damaged 18" subsea gas pipeline at a water depth of 2,300 ft. The Williams Canyon Chief pipeline was damaged by an accidental anchor drag that pulled pipeline 1,500 feet out of its original path, bent the pipeline to an unknown radius, and left a significant dent in the side of the pipe as well. The damage did not result in a leak and the pipeline was allowed to continue to operate at reduced pressure while repair plans were developed. Extensive research and testing determined that the pipeline could be returned to normal operating pressure if the dent could be restrained from flexing due to changes in pipeline pressure. Laboratory testing confirmed that cement grout inside a steel sleeve installed around the dent would provide the necessary reinforcement. A specially designed, ROV friendly repair clamp was developed to match the pipeline curvature that was estimated by side scan sonar imaging. The clamp was fabricated as a straight cylinder but the ends were angled and positioned off-center to account for the pipeline curvature. The clamp was split horizontally so that all clamping screws were vertical. An articulated spreader bar, ROV operated pull-down winches, and a large syntactic buoyancy module allowed the ROV to control the entire installation after the equipment spread was landed on the seafloor. A project specific metrology tool that measured the curvature of the pipeline at 24 points was built and landed on the pipeline. A ROV video record of the gauge readings was then used in the shop along with the metrology tool to fabricate a dimensionally correct mock-up of the pipeline. This mock-up was then placed into the repair clamp to confirm that it would fit on the pipeline.

Making equipment and logistic structures available to react immediately to environmental accidents and potential hazardous situations is essential in the current offshore oil and gas market. Saipem has a significant experience in deepwater and ultra deepwater special operations regarding recovery of contents from sunken vessels, pipeline and structure repair. Operations involve the use of a large marine spread, dependable work class ROVs and custom equipment. These operations require the ability to develop and deploy new technologies in a quick and efficient way, but also the capability to properly manage the execution and all interfaces of such complex projects. The first oil recovery performed by Saipem was in 2004 in approximately 4,000m water depth. In addition, Saipem has performed three other cargo recovery operations in the past five years, each of these presenting unique technical challenges. In the past three years seven large diameter pipelines, ranging in size from 20" to 36", have had major damages, with severe impact on productivity and financial results of operators. Impacts of such undesired events can be reduced by planning in advance for pipeline repair, which can be accomplished through several methods: provide a complete suite of remote equipment onsite during the pipeline installation, or have it on available on demand as needed. Managing the availability of proper assets, equipment, services, logistics and planning capabilities can dramatically reduce the downtime of a pipeline. The paper will include several case studies, describing initial damage or residual oil assessment, intervention preparations, new technologies introduced, assets utilized, organization and methodologies set-up and critical success factors. Introduction The offshore oil and gas industry is continuously evolving, with technically challenging projects, reaching into deeper waters, in harsher environments and in more remote areas, where logistics is a challenge in itself. As highlighted by the recent events in Gulf of Mexico, the impact of accidents can be dramatic for the environment, the economy, the health of local populations and for the safety of all offshore personnel. The contribution of offshore infrastructures (rigs, production facilities, pipelines) to meet the energy demand of many different nations is increasing. It is essential to keep the infrastructures operational, preventing any spill into the environment and minimizing operator revenue loss. Despite the industry focus on prevention and reducing accident risk, experience shows that these are always possible. The capability to respond effectively and rapidly to unexpected events is therefore of the utmost importance. It must be ensured that proper equipment is available, methods for interventions are tested and organizations are prepared to face the challenges posed by these occurrences, where direct human intervention is unsafe or simply not possible at all. Sonsub, as part of the Saipem Group, provides the group with competencies in ROV, Remote Intervention Systems and Subsea Robotics. Direct control of its highly sophisticated technologies, internal R&D, design and manufacturing capabilities, competent and trained personnel enable Sonsub to provide the most reliable and innovative tools to carry out complex remote operations in harsh and challenging environments, not only during normal operations but also during accident response situations.