Preventing clogging of debrining tubing in a gas storage salt cavern during construction

Abstract

Insoluble sediments may block the debrining inner tubing (DIT) in a salt cavern during construction. Most previous studies of this problem have simplified the sediment particles to spheres, which leads to significant errors in the predicted moving critical velocity of these sediment particles. In this paper, the morphological and hydraulic characteristics of sediments are quantitatively analyzed by a series of experiments. A model for calculating the minimum moving critical velocity of irregular sediment particles is established. Preventive measures for the clogging of DIT are proposed. Results show that the statistical mean values of sphericity and area circularity of sediments are 0.44 and 0.56, respectively. The moving critical velocity of sediments is much smaller than that of spherical particles of the same mass. The shape coefficient can characterize the drag coefficient of irregular sediment. Reasonable control of the minimum safe distance (MSD) between DIT and the sediment surface is an effective method to prevent DIT clogging. If the debrining rate is decreased from 200 to 20 m3/h, the MSD can be decreased from 2.49 m to 0.2 m, which can increase the debrining brine volumes and the working gas volume of the cavern. The MSD in the Jintan underground gas storage salt cavern can be optimized from 4 m to 0.9 m, which can increase the working gas volume of 2.734 million m3. Research results provide a technological reference for preventing clogging of DIT and the optimization of debrining parameters.