AS-BUILT SURVEYING FOR THE FACILITY RETROFITTING OF AN OFFSHORE GAS PLANT USING LEICA SCANSTATION 2 HIGH DEFINITION SURVEYING INSTRUMENT
3D as-built models have been utilized over the years as an aid to several engineering activities and there are conventional survey methods; e.g. Total Station ray method, photogrammetric technique etc., with which the data required for these models are generated. These methods have proven not to be optimal in capturing datasets required for the modeling of some complex engineering structures. The reasons for this been the intrusive nature of some of these methods and their point rather than surface sampling abilities.Others include the time taken to generate enough data as required and the average overall low accuracy achievable by these methods. This had led to several 3D models been a product of various degrees of interpolations and its attendance loss in model accuracy. High Definition Surveying (HDS) is a non-intrusive surveying method for collecting timely, accurate and complete geometric data of existing sites and structures.The HDS method has the capability of capturing tens of thousands of surface points in a second, making it very suitable for generating data required for the modeling of complex surfaces and structures. In this project, the ability and suitability of the HDS technique for use in complex and usually volatile oil and gas environments were proven as it was utilized for the production of the 3D model required as an aid for the retrofitting of an offshore gas platform. The Leica ScanStation 2 was deployed for the data capture alongside the Cyclone application program, the Cyclone program was also utilized for the processing of the measured data as well as production of a topologically and geometrically accurate 3D model of the required section of the platform. The produced model was subjected to some physical tests/checks to certify its correctness. Data interoperability was also achieved as the resulting 3D model as well as cloud of points were viewed and analyzed from various application programs e.g. AutoCAD. Further research was however recommended especially in the area of methods of quality assurance of completed models as the physical methods currently been utilized is not only slow, but also gives an indication of the presence of an error without giving an idea of its source and how it can be corrected.