Suitability Analysis of Subsea Pipeline Route using GIS

The objective of this study is to analyze the least cost subsea pipeline route using GIS. A past
project has been adopted in this research. The GIS-generated pipeline route is compared with
the existing pipeline route designed using contemporary method. The subsea pipelines are used
for hydrocarbon transportation from offshore platform to onshore plant. Criteria considered in
least cost path are cost, pipeline routing criteria, installation method, safety and maintenance
aspects. Factors affecting pipeline routing include bathymetry, submarine geographical features
such as seabed conditions and slopes, obstructions such as coral reefs, wildlife preservation
areas, as well as availability of existing services such as pipelines and platforms. Spatial
Analyst extension in GIS is used to analyze all these factors through three basic steps and
produce the best pipeline route through cost-weighted distance function. First step involves
developing discrete cost surfaces in raster datasets from routing criteria datasets. Second step
involves combining and weighing all discrete surfaces to create an accumulated cost surface.
Third step involves developing least cost path between the source and destination along the
accumulated cost surface. The result generated has shown similar alignment with the existing
route. The GIS-generated route is 0.09km longer than the existing route. Although longer in
length, the least cost route crosses less steep areas at length of three times more than the
existing route. It crosses prawns' areas at 4% less than existing route as well. Therefore, the
least cost path reduces the construction cost and increases the ease of construction as compared
to the existing route. Hence, GIS-generated route satisfies the criteria of economical, least
obstructions, safe and ease of construction in producing subsea pipeline route. Comparison
between GIS method and contemporary pipeline routing method highlighted unique benefits of
GIS that proved its feasibility in pipeline routing improvisation.