Applying directional wells to improve the salt rock utilization ratio in Jintan salt-cavern gas storage

In order to solve the problems in the block of salt-cavern underground gas storage (UGS), such as difficult well arrangement, fewer wells, insufficient storage capacity and working gas volume to meet the UGS building need of the block, this paper analyzed directional well trajectory design, casing running and other problems, and then put forward the design scheme of cluster direction injection/production well in salt-cavern underground gas storage suitable for the geological conditions in Jintan Salt Mine. According to the scheme, the number of wells in the block is increased from 12 (early feasibility scheme) to 20. Compared with the conventional pattern shape of vertical well, the pattern shape of directional well increases the number of wells by 60 % and its economical and social benefits are more remarkable. Practice indicates that directional drilling is suitable for Jintan Block, and it can increase the storage capacity greatly and make rational use of the salt mine resources to the uttermost. It has been applied on site 18 well times in Jintan Block. It is shown that all parameters of well quality satisfy the UGS building requirements. Therefore, it can be applied to the other salt-cavern UGS blocks and it is of great significance to accelerate domestic salt-cavern UGS building efficiency.