Numerical studies to assess the effects of seismic activities on underground oil and gas pipelines

This research aims to investigate and compare the effects of seismic activities on steel pipelines with varying characteristics and subjected to different conditions, particularly in terms of their design to accommodate large fault movements for pipeline protection. Two-dimensional numerical modeling was conducted using Rocscience-RS2 software on embedded pipelines to assess the effects of pipeline and soil properties on the pipe response when subjected to seismic horizontal loads. Six cases were analyzed for single, double, and triple pipelines, considering each to be either empty or pressurized, by varying one of the specified parameters while keeping the others constant. The study focuses on the outputs of the analysis regarding shear forces and horizontal displacements along the perimeter of the pipeline section. The software's outputs were then plotted using Microsoft Excel and AutoCAD to gain a clearer understanding of each case. As a final step, a case study was conducted on the consequences of the 2023 Turkey earthquake on the Iraqi-Turkish pipeline, which closely aligned with the findings. The comparison of the results indicates that FEM analyses using RS2 are reliable for effectively analyzing the pipeline's behavior under seismic events, as Rocscience-RS2 is capable of calculating forces at an exact point on the pipeline wall, in addition to accurately modeling its movement. Besides, it is capable of determining the forces and displacements of pipelines exposed to a single shock (one-directional strike), providing values for each direction of the model separately, which is particularly beneficial in sloped areas and induced seismicity.