RIASSUNTO
ABSTRACT
Â
Sophisticated engineered backfilling by a dynamically positioned fall pipevessel, as well as more conventional methods for precise engineeredbackfilling, are described in this paper.
Â
Reasons for the application of backfilling are, in the first place, alogical result of the described hazards to pipelines, followed by generalprotection methods for these pipelines.
Â
Applications of engineered backfilling, together with some relevant theorieson stability and size of the backfill material, are followed by a descriptionand operational procedures of the fallpipe vessel, accompanied by some casehistories.
INTRODUCTION
The ever-increasing exploitation of offshore oil and gas fields has resultedin a substantial increase in the offshore pipeline mileage over recent years.The overall safety record of pipeline transport is very good, which must mainlybe attributed to proper protective measures and adequate design.
Â
The harsher environmental conditions, the ever-increasing water depth andpipeline diameters have resulted in new laying techniques. The development ofprotection methods must keep pace in order to ensure the safety of theselines.
Â
The latest development arose from the need to cover a part of theEkofisk-Emden pipeline. The requirements for this project created the need forthe development of new engineered backfilling methods. As a result, a d.p.vessel with a fallpipe system has been developed (which is described here),together with other methods and their specific applications, in order to ensureproper protection under the most difficult circumstances in the years tocome.
HAZARDS TO SUBMERGED PIPELINES
The hazards to submerged pipelines are divided into 5 categories:
overstressing of the pipe
instability of the pipe at the sea bed
mechanical impacts
corrosion
others
Â