0 引言
1 盖层损伤模拟及动态密封性实验评价方法
1.1 实验样品
表1 储气库盖层基础参数Table 1 Basic parameters of UGS caprocks |
储气库 | 盖层岩样平均埋深 /m | 盖层岩性 | 盖层厚度 /m | 平均孔隙度 /% | 平均渗透率 /(10-3 μm2) | 平均密度 /(g/cm3) | 水平最小主应力 /MPa | 水平最大主应力 /MPa | 覆压渗透率 /(10-3 μm2) |
---|---|---|---|---|---|---|---|---|---|
D储气库 | 3 460 | 粉砂质泥岩 | 188 | 6.51 | 0.065 | 2.44 | 68.4 | 86.5 | 0.001 1 |
S储气库 | 2 836 | 32 | 2.56 | 0.012 | 2.62 | 56.6 | 77.8 | 0.000 5 |
1.2 实验流程
图3 不同岩性岩石突破压力/排驱压力与渗透率关系Fig.3 Relationships between breakthrough pressure and entry pressure and permeability of rocks with different lithologies |
1.3 实验方案
2 实验测试结果
图6 盖层岩样损伤前后不同周期密封对比Fig. 6 Comparison of cap rock samples’ sealing capacity in different gas injection-withdrawal cycles pre- and post-damage |
图7 D储气库盖层岩样损伤前后多周期密封能力演化特征(a) D储气库完整盖层损伤前密封能力演化特征; (b) D储气库盖层损伤后密封能力演化特征 Fig.7 Sealing capacity evolution of cap rock samples from UGS facility D under multicyclic gas injection and withdrawal before and after damage |
3 盖层损伤前后力学参数演化与密封机理
图10 盖层岩样损伤前后力学参数多周期变化特征(a) D储气库完整盖层样品力学参数演化特征; (b) S储气库盖层样品力学参数演化特征 Fig.10 Changes in the mechanical parameters of cap rock samples under multi-cycle gas injection and withdrawal pre and post-damage |