Determination of convergence of underground gas storage caverns using non-invasive methodology based on land surface subsidence measurement

Abstract

Underground gas storage caverns are monitored for environmental safety in terms of equipment and potential emissions, particularly methane emissions from the underground and above-ground parts of the storage facility. Periodical measurements of land surface deformations and costly echometric measurements of convergence of individual storage facilities are carried out. The aims of environmental monitoring are: (1) to eliminate potential hazards in the shortest time, (2) assess the overall impact of intensive operation of storage facilities on the environment, (3) develop monitoring methods relevant to environmental protection, and (4) take actions in case of failure. The paper presents a solution to the problem of determination of the convergence of underground caverns in a salt rock mass based on the results of land surface subsidence measurements carried out using the Gauss-Markov equalization algorithm. The method makes it possible for ongoing control of cavern volume convergence after each subsidence measurement on the ground surface and determining the actual impact of the use frequency (injection - medium consumption) on the convergence in time. The presented methodology is universal and verified on caverns located in a salt rock mass. The Gauss-Markov inversion model is the first used in this area, hence its application is significant.

Keywords

• Underground storage
• Salt cavern
• Convergence
• Subsidence
• Surface deformation