ORIGINAL ARTICLE A fuzzy multi-criteria decision support system for evaluating subsea oil pipeline routing criteria in East Malaysia Abdul-Lateef Balogun 1 • Abdul-Nasir Matori 2 • Adekunle Isa Hamid-Mosaku 3 Received: 22 September 2014 / Accepted: 30 April 2015 Ó Springer-Verlag Berlin Heidelberg 2015 Abstract Selecting suitable pipeline routes is essential to the success of any oil exploration and transportation pro- ject, and proper prioritization of the diverse routing criteria is an integral component of the route selection endeavor. However, recent researches reveal that accurate prioriti- zation of routing criteria, particularly in an offshore/subsea environment, has not been sufficiently addressed. With global attention rapidly expanding from terrestrial explo- ration to offshore and subsea oil pipeline operations, this study addresses the offshore pipeline routing ranking concerns. A hybrid multi-criteria decision support system was developed by integrating fuzzy logic-based ap- proximate reasoning (AR) and Analytic Hierarchy Process (AHP) mathematical models. Twelve diverse criteria and sub-criteria in an oil-rich basin offshore east Malaysia were examined to determine their impact in the selection of an optimal pipeline route in the area. These were subsequently classified into three broad categories: economic, engi- neering, and environmental routing criteria. The integrated system (AR-AHP) was used to determine the relative im- portance of the criteria using different fuzzy membership functions and linguistic variables. Final results showed that the environmental criteria in the study area have the highest aggregated priority and influence (61.4 %) fol- lowed by the engineering criteria (27.6 %) and the eco- nomic criteria (11 %) datasets, respectively. This study thus establishes the fact that preservation of environmental factors is superior to the other strategic criteria in the marine study area. Keywords AHP  AR  Decision support  Fuzzy logic  Offshore  Pipeline  Route selection Introduction Higher energy prices and growing energy consumption are expected to stimulate several oil and gas exploration and transportation projects in the coming years and many of these projects will be in the Asia–Pacific region where Malaysia is a major player (Tubb 2009). Oil exploration and transportation has traditionally been onshore (Smith 2011, 2012). However, recent discoveries about the bene- fits of offshore exploration are beginning to stir more in- terest in offshore product transportation. For instance, regular depletion of onshore oil and gas reserves is forcing companies to seek alternatives in offshore solutions. Con- sequently, submarine pipeline corridor and route selection are becoming extremely important and will attract more attention in the future (Oynes 2004; Robertson et al. 2004; Chai et al. 2006). Selecting suitable pipeline routes is a strategic compo- nent of a company’s pipe laying activities. Proper pipeline routing is perhaps the single most important element in the development of transmission lines (Khene 1997; Degermenci 2001). The pipeline route selection process focuses on achieving the optimal location for a pipeline. Electronic supplementary material The online version of this article (doi:10.1007/s12665-015-4499-z) contains supplementary material, which is available to authorized users. & Abdul-Lateef Balogun geospatial63@gmail.com 1 Geomatic Engineering Department, Yanbu Industrial College (YIC), Yanbu Al-Sinaiyah, Kingdom of Saudi Arabia 2 Geomatic Research Group, Department of Civil Engineering, Universiti Teknologi PETRONAS (UTP), Perak, Malaysia 3 Surveying and Geoinformatics Department, University of Lagos (UNILAG), Lagos, Nigeria 123 Environ Earth Sci DOI 10.1007/s12665-015-4499-z