Seal-preservation conditions of gas reservoirs and its relation to reserve abundances in the Xujiaweizi Fault-Depression

By anatomy of gas reservoirs in the Xujiaweizi Fault-Depression, it was considered that the seal-preservation ability of gas reservoirs might he mainly influenced by the thickness, displacement pressure of cap rocks and the pressure of gas reservoir. According to the 3 main controlling factors, by use of weighted average method, the seal-preservation ability of 19 gas reservoirs in the depression was quantitatively evaluated. It was concluded that the seal-preservation ability was good for majority of 19 gas reservoirs in the depression, and the subordinate was middle. There were not gas reservoirs with bad seal-preservation ability. Based on a study of the relation between comprehensive evaluation results for seal-preservation ability and gas recoverable reserve's abundance of gas reservoirs, it was considered that the recoverable reserve's abundance of gas reservoirs with good seal-preservation ability was the highest. It indicated that the good seal-preservation ability should be required in forming gas re