Use of an Electronic Imaging System on a Major Offshore Project

Abstract

1. ABSTRACT This paper highlights the experiences of introducing Electronic Imaging to a major offshore project in Norway, to store and distribute all drawing documentation. The paper describes the objectives and features of the system and ultimately practical experiences with the system. The paper concludes by recommending it as a powerful tool for future major projects. 2. INTRODUCTION Gyda is a $1.3 billion project to develop an integrated oil platform in the Norwegian sector of the North Sea. It has a production capacity of 60,000 BPSD and delivers oil to Teesside in the UK and gas to Emden in West Germany. The purchase of an Electronic Imaging System arose as a result of a requirement for CAD facilities during the fabrication, installation and commissioning phases of the project. After a thorough investigation of possible alternatives it was considered that Electronic Imaging was the only method of accommodating all the dissimilar drawing media inherited from the Norwegian design contractor (Figure 1 shows a breakdown of the media received from the contractor). Prior to "close-out" of the detailed design Contractor, 16,500 design and supplier drawings were scanned over a period of 4 weeks. As a temporary measure all scanned data was stored on magnetic tape prior to delivery of the system in April 1989. One of the major justifications for making all drawings electronic on the project was the fast transmission of drawing documentation to the widely dispersed remote sites on the project (Figure 2 shows the geographical locations of the remote sites accessing the Electronic Imaging System). There are two alternative methods of storing drawing data on an Imaging System known as "Raster" and "Vector". Raster data is received directly from a document scanner and is rather like an electronic version of a high resolution tealeaf image. The drawing, once scanned, is represented as a series of non-intelligent dots at a density of 200 Dots/inch. Vector data is more intelligent and is made up of geometric entities such as lines, arcs, circles, etc., the entities can be manipulated as self contained objects. CAD systems exclusively use Vector data, but Imaging Systems can use a combination of both to fit the purpose. They also have the capability to convert Raster data into Vector known as "factorizations". Raster drawing data requires a lot of storage space, therefore it is necessary to use data compression techniques to reduce storage demands. On Gyda all drawing data is held as highly compressed Raster data and no attempt has been made to convert this into Vector data. Since timescales were short and the compressed image file sizes were slightly less than Vector, it was decided to edit and store drawings solely in Raster.