金坛盐穴储气库上限压力提高试验

为了精确获取造腔层段最小主应力以确定盐穴储气库上限压力，确保气腔安全稳定运行且最大限度地发挥盐穴储气库的功能。在金坛储气库进行小型水力压裂地应力测试，测量5个层段的最小主应力，选取注采B井套管鞋处最小主应力22.5 MPa的80%，即18 MPa作为理论上限压力。上限压力的确定需进行数值模拟，研究表明，注采B井在上限压力18 MPa下满足气腔稳定性和密闭性的要求。根据注采站压缩机技术参数和安全考虑，金坛盐穴储气库确定了上限压力提高0.5 MPa的方案，且提压过程中利用实时微地震技术监测腔体及围岩的稳定性。经过现场提压试验，注采B井上限压力达到17.5 MPa，库容从3 481.06×10⁴ m³增加到3 590.39×10⁴ m³，工作气量从2 137.02×10⁴ m³增加到2 246.15×10⁴ m³，增加了5.11%。研究认为：虽然盐穴储气库行业普遍采用最小主应力的80%~85%的经验值作为盐穴储气库上限运行压力，但采取的上限压力需要进行数值模拟。通过理论模拟研究和现场试验，金坛盐穴储气库上限压力可以从当前的17.0 MPa提高到17.5 MPa。

Maximum Pressure Threshold Increase Test for Jintan Salt Cavern Gas Storage

The objective of the present study was to accurately ascertain the minimum principal stress of the gas chamber layer of salt cavern gas storages in order to determine the maximum pressure threshold, thereby ensuring the safe and continuous operation of the gas chamber and the maximization of the function of salt caverns. Small-scale hydraulic fracturing tests were carried out in the Jintan salt cavern gas storage to measure the minimum principal stress in five layers. Eighty percent of the minimum principal stress of 22.5 MPa (i.e., 18 MPa) at the casing shoe of the injection-production well B was selected as the theoretical maximum pressure threshold. The maximum pressure threshold was also determined using numerical simulation. The results showed that the injection-production well B met the gas chamber stability and airtightness requirements at the maximum pressure threshold of 18 MPa. A 0.5 MPa increase in the maximum pressure threshold was determined for the Jintan salt cavern gas storage based on the technical parameters and safety considerations of the injection-production station compressor. Real-time microseismic technology was used to monitor the stability of the chamber and the surrounding rock during the pressure increase process. After the on-site pressure test, the maximum pressure threshold of the injection-production well B reached 17.5 MPa, the storage capacity increased from 3, 481.06×10⁴ m³ to 3, 590.39×10⁴ m³, and the functional gas volume increased by 5.11% from 2, 137.02×10⁴ m³ to 2, 246.15×10⁴ m³. Although the industry generally uses the empirical value of 80%~85% of the minimum principal stress as the maximum pressure threshold for salt cavern gas storages, our study showed that the maximum pressure threshold needs to be numerically simulated. Based on the theoretical simulation studies and the field test results, we have determined that the maximum pressure threshold of the Jintan salt cavern gas storage can be increased from the current 17.0 MPa to 17.5 MPa.