Objective An approach on abandonment and removal of steel platforms technology based on the following topics :- The analysis of the problems associated with decemmissioning and removal of steel platforms larger and heavier than those removed in the past.- The study of feasible solutions from a technical and economical point of view, taking into consideration regulatory requirements, available subsea cutting techniques and existing high capacity crane barges.- A comparative analysis among different methods for topsides removal : reverse the installation procedure, remove the equipment and scrap the structure.- A comparative analysis for the jacket removal among the following methods : demolition, reflotation and lifting.- Development of cost estimates for the various studied removal methods.- Establishment of design guidelines to introduce during the project phase to allow a simpler and cheaper platform removal.Results obtained at this stage of the project are summarized hereinafter :1. Phase I. Review of the state of the art on abandonment and removal of offshore steel platforms. The study showed that there are several methods to remove both "topsides" and "jackets" depending on which marine spread is used, and even more using different marine support vessels for the "topsides" removal than for the "jacket" removal.However as a result of the study the most interesting removal methods to apply are the following :1. 1 Topsides and decks removal : Reverse lifting by crane barges, hanging from barges, equipment scrapping and demolition of deck structure.1. 2 Jacket removal : Lifting by crane barges, hanging from barges, refloating, toppling.2. Phase II. Legislation applicable to offshore platform removal enacted by international organizations and E. E. C. countries.The most important event regarding this subject is the issue of the Guidelines and Standards for the Removal of OffshoreInstallations and structures on the Continental Shelf and in the Exclusive Economic Zone by IMO (International Maritime Organization).This guidelines and standards were approved by the I. M. O. Maritime Safety Committee at its session in April 88 and one reviewed in April 89 with comments received from different international organizations will be submitted to the IMO Assembly for approval at its session due in October instant.3. Phase III. Platform Data Base.A platform data base programme has been developed, compiled data of offshore platforms and loaded in the data base.The programme presents different application such as listing of Platforms in alphabetic order, or group them by jacket weight range, water depth, etc.4. Phase IV. Study of different technologies related to platfrom members cutt off.A survey has been done of current and proposed methods to apply for underwater cutting of steel members.The first stage of this phase summarizes the "State of the Art" on thisparticular subject, describing each method with its application range, its advantages and limitations.The study focuses the application of techniques, lists equipment and resources requirements, and discusses efficiency and reliability of the the related methods of cutting.5. Phase V. Study of "Topsides" removal. "A detailed study has been done topsides removal for three types of platforms :Type "A". The jacket heigh is less than 100 metres and the total weight is not exceeding 4000 tonnes.Type "B". The jacket heigh is between 100 and 120 metres and neither the jacket nor the topsides weights exceed 12000 tonnes.Type "C". The jacket heigh is higher than 150 metres and both the jacket and the topsides weight exceed 12000 tonnes.The main phases and activities of the project are as follows : Phase I. Study of existing methods related to abandonment and removal of steel platforms.Phase II. Compile existing regulatory requirements taking into consideration legislation and recommendations established by international organizations and specific regulations which may be applicable in E. E. C. countries.Phase III. Collect, analyse and log all available information from case histories of platform installation and removal.A platform data base using latest Data Base Management System is developed which contains platform categorization and relevant information regarding operator identity, field data, platform features, etc.Phase IV. Study of underwater cutting methods.An analysis of underwater cutting methods is carried out. Methods under study are cutting with explosives, waterjet, oxy-acetylene, mechanical cutting, etc.Phase V. Study of topsides removal.The methods subject to study are the following :- Reverse lifting by crane barges.- Hanging from barges.- Demolition.Phase VI. Study of jacket removal for series of typical cases.This phase consists in a technical evaluation of different "jacket" removal methods listed below :- Lifting the "jacket" by crane barges.- Floating the "jacket" with auxiliary buoyancy bags.- Hanging the "jacket" from barges. - Toppling the "jacket" on the sea floor.Phase VII. Develop cost estimates for the various applicable removal methods.In this phase a cost estimate is done for the different activities and operations performed in every platform removal case. Programme(s) ENG-HYDROCARB 2C - Programme (EEC) of support for technological development in the hydrocarbons sector, 1986-1989 Topic(s) 1.3 - ENVIRONMENTAL INFLUENCE Call for proposal Data not available Funding Scheme DEM - Demonstration contracts Coordinator REPSOL EXPLORACION SA EU contribution No data Address PEZ VOLADOR 2 28007 Madrid Spain See on map Total cost No data
