Challenges at Pipeline Crossings: a Holistic Anatomy of New Mol 1.2 and 3.5 Pipelines Construction

Abstract During the construction of new MOL 1.2 and 3.5 pipelines, the routing of the pipelines crossed several facilities such as Etihad railway, black-top roads, and Ruwais refinery east and west. In total, sixteen (16) numbers Horizontal Directional Drilling (HDD) were performed and one (1) number micro-tunneling at a black-top road crossing. Moreover, four (4) numbers open cuts were performed. The paper highlights the several challenges encountered during HDD at these crossings during the construction of new MOL 1.2 and 3.5 and how these challenges were overcome. The paper discusses the challenges encountered at the Etihad railway, black-top roads, and Ruwais refinery east and west road crossings during HDD, open cut, and micro-tunnelling for the new MOLs 1.2 and 3.5. With the different terrains and soil nature, high-water table, difficult ground conditions, several road crossings and refinery roads as well as the many crude and gas pipelines on the ROW, the project became riskier without a proper qualitative risk assessment. The pipeline installation methods adopted for this project were mostly HDD in addition to the open cuts, and micro-tunneling methods. These were performed on each of MOLs 1.2 and 3.5. A total of 16 HDDs, 4 open-cuts and 1 micro-tunneling were carried out, with the deepest HDD of 24 meters at the railway crossing, whereas the micro-tunneling was 10 meters deep. Four (4) open cuts were performed with 2 each for MOLs 1.2 and 3.5 at maximum depths of 3.5 meters. Out of the 16 HDDs, 8 no's were on MOL 1.2 and the other 8 HDD were on MOL 3.5, with 1 micro-tunnel casing for both MOL 1.2 and 3.5. There was no method other than HDD, most especially in Refinery and Etihad crossing locations due to the delicate nature of their operations as well as lack of alternative routes in the refinery road network as well as railway. For each HDD, it took between 45 to 60 days with prior permission such as NOCs, clearances from Etihad railway team and refinery authorities as well as municipalities with similar permissions obtained for the open cut method at the road crossings. Challenges encountered such as coating damage of inserted pipes, hole settlement immediately after drilling, angle of pipe lifting were encountered and addressed. The paper discusses the approach followed during the planning and execution of the project and highlights the challenges and how they were addressed. Adoption of different pipeline installation methods remains essential in the construction of new pipelines for conveying crude oil that crosses several critical facilities, and where several obstacles exist, as in this case study; HDD is the most optimal approach. This paper fills the gap in knowledge on pipeline installation methods, and approaches addressing them in a cost-effective way without compromising safety. It serves as a knowledge base for the training and development of young UAE nationals in pipeline engineering, installation and construction.