Pore Structure and Brine Flow Simulation of Salt Cavern Sediments Based on X-ray Computed Tomography

Enhancing natural gas storage capacity by utilizing the pore space of sediments in cavern bottoms holds significant potential, particularly in high impurity salt formations. This study presents comprehensive insights into the pore structures of sediment samples through the application of X-ray computed tomography imaging. Three-dimensional reconstruction models were employed to extract and quantitatively analysed the pore network characteristics. Fluid flow simulations were conducted to investigate the non-uniform distribution of the brine velocity field, influenced significantly by particle size. Probability and cumulative distribution curves of pore equivalent radius, pore coordination number, pore throat equivalent radius, and throat length were effectively fitted using the log-normal and Boltzmann functions, respectively. Notably, the permeability of partial packings exhibited a positive correlation with porosity and displayed an upward trend in correlation with particle size. Moreover, during the debrining process, sediments comprising finer particles exhibited a higher susceptibility to blockage, thereby escalating the risk of particle clogging. These findings offer valuable insights for the development of anti-clogging strategies during debrining operations. Expanding storage capacity: Storing natural gas in the pore space of sediments in cavern bottoms offers a significant increase in storage capacity in high impurity salt formations.X-ray computed tomography analysis: The use of X-ray computed tomography allowed for the reconstruction and quantitative analysis of the pore structures and pore network models of the sediment samples.Fluid flow simulations: Three-dimensional simulations of fluid flow in the packing samples provided insights into the non-uniform distribution of the brine velocity field and its dependence on particle size.Permeability and particle blockage: The study revealed that permeability of the partial packings exhibited a positive correlation with particle size. Fine particles were found to pose a higher risk of blockage during debrining, highlighting the importance of anti-clogging methods in the process.