Optimal pipeline planning is an emerging problem of the environment and economic development in uneven terrain areas that requires the most sophisticated scientific methods of path analysis. During planning of the most suitable routes for pipeline, the topography, proximity to the road, settlement, water resources, protected sites and other critical landmarks have always acted as an important role as a constraint. With the Application of Analytical Hierarchical Process, the suitability analysis to derive the relative preferences of the different factors affecting the route is achieved. The Least-Cost Path Analysis (LCPA) method provides designers a way to find the “cheapest” way to connect two locations within a cost surface, which can be computed by combining multiple criteria, and therefore by accounting for different issues (environmental impact, economic investment, etc.).
Formerly, stakeholders in the Petroleum distribution industry mostly focused more on choosing the shortest and most direct pipeline route for the distribution of petroleum products. This is primarily to save costs on construction and other capital expenditure reasons. However, several other factors apart from cost have to be considered in the route selection process. Geophysical, environmental, political, economic, social and regulatory factors all have significant influences on the route selection process (Dey & Gupta, 1999).
Pipeline systems are very important for transporting gas, oil and petroleum products because they are the most cost-effective way of moving fluid products over long distances (Yildirim, Yomralioglu, Nisanci, Erbas, & Bediroglu, 2013). The significant impact of these transported resources on the national economy and security makes it imperative to determine reliable and affordable methods to transport them. Pipeline transport is most predominant around the world and in the USA nearly two-thirds of the ton-miles of oil get transported annually through a network of more than two million kilometers of pipelines, in some of the toughest terrains (Dubey, 2009). “Determination of the shortest and most direct and efficient route is a primary objective to minimize fuel travel time and capital expenditure. The distances between the source of petroleum products and their destination for energy transitions can span hundreds of miles with varying terrain” (Opara, 1999).
Ghana’s Petroleum Products distribution operations lack adequate transportation (pipeline routes) and available storage facilities which further obstruct the safe transportation and consistent storage of oil and gas products, there are some pipelines inside the country but they run from the refinery to Akosombo. Furthermore, the availability of these pipelines running through to Akosombo is not enough to prevent products shortage. In addition, Bulk Road Vehicles (BRV) that transport from the oil refinery to other transport points greatly contribute to the frequent accidents and congestions on our highways. The southern and mid part (being the Western, Central, Ashanti and some part of the Brong-Ahafo Regions) of the country lack a properly engineered pipeline transportation system. Hence as stated above the operation of these BRVs is mostly utilized in the distribution of petroleum products which, for the most part, are not efficient, safe and convenient in transporting oil products. According to the 2010 world population census census data collected in Ghana that the final results from the regional breakdown shows, Greater Accra (16.3%) and Ashanti (19.4%) regions had the greater share of the population while upper East (4.2%) and Upper West (2.8%) regions had the smaller share of the population (Ghana Statistical Service, 2012). This is to conclude that, the southern and mid parts of the country have the largest occupancy ratio as compared to the Northern part of the country. Therefore, the consumption of petroleum products is very high since there are major factories, companies, agricultural, fisheries and other commercial operations which require high patronage of various petroleum products.
Suitability Analysis for Ghana: Methods and Materials
About the Study Area
The study area as shown in fig. 1 falls within the mid to the Southern parts of Ghana. Namely the Brong-Ahafo, Ashanti, and Central and Western Regions.
GIS Data used for Ghana Study
The spatial dataset was organized using ArcGIS 10.4 for data processing. All the available datasets mention was in a vector data model, and are later converted into the raster model. The datasets were organized in layers for convenient data processing which involved derivation of relevant parameters from selected datasets.
- Slope_ DEM layer
- Land use Layer
- Water Resources layer
- Linear features e.g. Main roads and railways lines
- Geological layer
- Settlement layer
- Protected sites layer
- Soils type layer
Steps to Find the Optimum Route
In application, the best Optimum route is found for a petroleum product pipeline. The steps to produce such a path are outlined below. The path is performed using ArcGIS 10.4 Spatial Analysis Module.
- Create Source, Destination
- Create Cost Datasets
- Generate A Thematic Cost Map (Classify and Weighting)
- Perform Cost Weighted Distance
- Create Direction Datasets
- Perform Shortest Path with Distance and Direction Datasets
- The least-cost path developed
With the advanced application of Geographic Information System, it is possible to compute the shortest route of linear features with associated costs which ineluctably can reduce the cost and time of project execution and hence the operating expenses. GIS provides a variety of analytical functions that are capable of superseding manual and traditional methods of route planning. The integration of GIS and the Spatial Multi-criteria decision support system offers a baseline for multiple kinds of decision making where a variant nature of criteria and stakeholders can be catered successfully.
From the analysis of this study the generated least-cost paths shown in fig. 5 are found to be more convenient than the existing highway route taken by the BRVs in the distribution of Petroleum Product. However, when judging it in terms of factors that determine the cost of construction, the least-cost-paths are better than the existing highway routes since it crosses fewer steep areas and its lengths are shorter than the existing routes as shown in table 1.
The comparison of the important factors in determining the pipeline routes are summarized in Table 1. From the table above the existing highway routes commonly used by Bulk Road vehicles have long traversing distance as compared to the developed optimum pipeline routes. Taking for instance the highway route from the Refinery in Tema to Saltpond in the central region has a length of 144km and with an increase in the crossing of waters resources. Comparing it to the Pipeline route from the refinery to Saltpond, the length of crossing flatter areas is maximum for least-cost-path, being 133km as compared to the existing 144km highway route. Again, the effect of crossing water resources is highly minimized for the route.
Also, taking the highway route from Saltpond to Badukrom in the Western Region has a length of 69km with a slope of 4.2◦. However, the least cost pipeline path developed has a shorter length of 63km with no effect on the crossing of water resources along its path and a flatter slope of 2.7◦.
Saltpond to Anyinam highway route in the Eastern Region has a length 87km on the other hand a developed least cost pipeline route of length 76km from the same source to the same destination point with a slope of 2.8 ◦ as compared to the highway steeper slope of 8.9 ◦.
The last developed least cost pipeline route from Anyinam to Kubease in the Ashanti region has a length of 106km passing through a less stepper slope terrain with a limited crossing of water resources and other features of important as compared to the highway route of length 133km.
From table 1 discussions, it can be therefore be stated that the pipeline routes fulfill the top priorities which are the safety and cost in the route design process.
The pipeline routing criteria are identified and input into GIS. Spatial Analyst tool in ArcGIS 10.4 is utilized in the least-cost path analysis and a Multicriteria Decision Analysis method; the Analytical Hierarchical Process is applied to determine the weightages of criteria. The GIS-developed routes are far shorter than the subsisting highway routes utilized by the BRVs and again it crosses most of the flatter slope areas which contributes to truncation in pipeline construction cost. The developed routes have the best suitability to public consequently solving the frequent occurrences of contingency on our highway caused by the traversing of Bulk Road conveyances carrying petroleum products from the refinery to the sundry facility centers. In conclusion, the GIS approach is no doubt a more structured and consistent method than contemporary routing method because all the routing criteria and corresponding level of consequentiality in affecting pipeline construction cost are not only designated and documented limpidly but can withal be monitored to engender more routes according to different sets of weightages desired.
Dey, P. K., & Gupta, S. S. (1999). Decision Support System for Pipeline Route Selection. International Journal of Project Management.
Dubey, R. P. (2009). A Remote Sensing and GIS-based least cost routing of pipelines. Retrieved March 24, 2020, from Geospatial World website: https://www.geospatialworld.net/article/a-remote-sensing-and-gis-based-least-cost-routing-of-pipelines/
Ghana Statistical Service. (2012). 2010 Population and Housing Census Final Results. Retrieved from https://www.statsghana.gov.gh/gssmain/storage/img/marqueeupdater/Census2010_Summary_report_of_final_results.pdf
Opara, T. (1999). Pipeline Routing using GIS and Remote Sensing.
Yildirim, V., Yomralioglu, T., Nisanci, R., Erbas, Y. S., & Bediroglu, S. (2013). Natural Gas Transmission Pipeline Route Selection Using GIS and AHP. Research Gate, 90(462). Retrieved from https://www.researchgate.net/publication/312289377_Natural_Gas_Transmission_Pipeline_Route_Selection_Using_GIS_and_AHP
About the Author
About Bernard Amponfi Gyabeng (MSc., BSc) is a Geophysicist, Exploration Geologist, GIS Spatial Analyst and Geomatic Engineer who earned his Bachelor’s Degree in Geomatic Engineering from KNUST- Ghana and Master’s Degrees in Geophysical Exploration from the China University of Petroleum-East China. He works currently as a researcher in the School of Geosciences, China University of Petroleum-East China with a research interest in Geospatial analysis of Petroleum Pipelines Selection.