STABILITY ANALYSIS OF AN OFFSHORE PIPELINE LOCATED IN THE NIGER DELTA WATER WAYS

The stability of offshore pipelines in the Niger Delta is a pressing issue for the oil and gas industry, driven by the region's distinct environmental and operational challenges, including strong ocean currents, high sedimentation rates, and soft seabed soils.This study introduces a comprehensive stability analysis through a MATLAB-based computational framework that integrates hydrodynamic, geotechnical, and structural factors.The research simulates the influence of critical parameters such as hydrodynamic forces, burial depth, water depth, internal pressure, operating temperature, and outer diameter on pipeline behaviour under diverse conditions.The result shows that at a water depth of 23 m, the current velocity increases from 0.74 m/s (1-year return) to 1.54 m/s (1000-year return), and the significant wave height rises from 2.74 m (1-year) to 3.45 m (100-year).For the plots of the equivalent stress against varying levels of internal pressure within the pipeline.Internal pressure, specified as 1.2 N/m², is a critical operational parameter representing the force exerted by the transported crude oil (density 870 kg/m³) on the pipeline's inner walls.The simulation results suggest an optimal burial depth where stability is maximized without excessive costs.Given the soft clay and high scour risk (Shields parameter 0.05), a burial depth of approximately 1.5-2.0m (with a safety margin of 0.2-0.5 m) is recommended.This depth leverages overburden pressure while minimizing excavation in the variable seabed.Increasing the outer diameter beyond the baseline 0.508 m enhances stability and critical free span length.An outer diameter of 0.6-0.7 m is proposed, balancing stability gains with material and installation costs, as larger diameters improve resistance to lateral forces and scour-induced spans.Pipelines must withstand 100-year return period conditions (e.g., wave height 3.45 m, current velocity 1.27 m/s at 23 m depth).A safety factor incorporating these extremes ensures resilience against hydrodynamic forces, with materials and coatings selected to endure prolonged exposure to saline and sediment-heavy waters.Results indicate that hydrodynamic forces play a significant role in stability, especially during extreme events, while adjustments to burial depth and outer diameter can bolster resilience.Stress analyses further underscore the need to manage internal pressure and temperature to ensure structural integrity.