Earthquake Risk Considerations For Platform Topsides

This paper discusses the potential risks to the topside facilities of offshore platforms from an earthquake and describes what to look for during the initial topside design and/or dur-ing a later safety assessment review. There has, to-date, been no recorded earthquake damage to either topsides or to platform support structures, primarily because no plat-forms have been exposed to a significant earthquake. California, Alaska, Indonesia, Ja-pan, China and Peru are some of the active seismic areas with current offshore oil and gas development activities. Potential hazards to a platform operation from an earthquake are: process equipment damage, pipeline riser rupture, drilling rig or crane collapse, cantilevered deck framing failure, quarters building collapse, and, well or conductor failure. These hazards may re-sult in personnel injury or death and/or environmental pollution. Each of these possible incidents will be discussed. It will be demonstrated through both quantitative and quali-tative risk analyses that the risk of topside earthquake damage is relatively low, provided all equipment and piping are adequately restrained and the drilling rig and other slender structures are designed for the appropriate earthquake loading. The earthquake risk to the topside equipment, however, is quite often ignored