Objective This paper aims to enhance practices in the gas storage sector of China, specifically by improving the efficiency of cavity formation in layered salt rock, controlling the cavity regularity of salt caverns, expanding potential gas storage space within salt beds of limited thickness, and ensuring the safety of tubing strings during cavity building, gas injection, and brine displacement. To achieve these objectives, detailed geological modeling was conducted to reflect the exploration and drilling results from Jintan gas storage. The evolution trends of cavity shapes due to dissolution in this gas storage area were statistically analyzed, along with relevant cavity-building process measures. Furthermore, the influencing factors and action mechanisms of eccentric dissolution in the cavities were systematically investigated.

Methods The Jintan salt mine is situated within a typical multi-interbedded salt rock formation. A geological model for the regional development of salt rock and interlayers was established using three-dimensional seismic exploration results, along with data from single well logging conducted on a progressive basis. This approach allowed for a detailed characterization of the tectonic fluctuations of salt rock and interlayers. A subsequent study focused on the dip trends of interlayers close to the wellbores. Utilizing sonar data from cavity measurements at Jintan gas storage, the relationships of trends in shape expansion due to dissolution were analyzed in relation to the timing of eccentric dissolution and geological characteristics. By comparing the water injection dynamics and tubing string control strategies during the dissolution process in interlayer intervals across wells, the study explored the specific influences of relevant cavity-building processes on the development and control of cavity shapes.

Results The collapse of salt rock and interlayers within the stratigraphic structure around the wellbores at different times, along with disturbances caused by interlayer dips to the flow field within the cavities, were identified as fundamental geological factors leading to eccentric dissolution that affects cavity shapes. The vertical positional relationships of tubing strings used for cavity construction in relation to interlayers and water injection displacements were revealed to be key process factors contributing to the eccentric dissolution. Therefore, it is recommended to propose targeted and rational cavity-building process measures based on a detailed geological understanding.

Conclusion Salt mines in China are generally characterized by numerous interlayers and steep dips. It is recommended to progressively enhance geological understanding through the application of updated drilling and logging data in conjunction with exploration results. This strategy enables targeted design and control of cavities at risk of eccentric dissolution, improves cavity volumes and shape regularity, and reduces the investment cost of salt cavern gas storage. Consequently, it supports the efficient promotion of gas storage construction in complex stratified salt beds.