A Stability Analysis of Unlined Rock Caverns for Underground Oil Storage in Asmari Formation

Storing in unlined rock caverns is regarded as one of the major ways of underground oil storage where cavern stability and oil leakage are the most crucial parameters to be concerned. The stability assurance of the cavern can lead to safety of the underground structure during and after construction as well as preventing the oil leakage phenomenon. Therefore, stability assessment of the structure is considered as one of the most important parts of design, construction and operation. Thus, the important parameters affecting the stability of the cavern were recognized and discussed in this paper. It was determined that a suitable algorithm, independent of numerical methods, is required in order to conduct a reliable and applicable stability analysis. Accordingly, in addition to recognition of affecting parameters, an algorithm was introduced for stability assessment of unlined rock caverns. A case of a stability analysis for unlined rock caverns in Asmari formation via numerical methods is discussed. Geotechnical, geology and engineering geology information was employed for numerical modeling purposes. Prediction of deformation and displacement magnitude during excavation, and subsequently designing a support system consisting of rock bolt and shotcrete based on these predictions were the objectives of modeling. Finally, the sensitivity analysis of the important parameters on cavern stability and the designing support system was carried out.