0 引言
1 实验设计
1.1 实验材料与条件
表1 实验用岩心基本物性参数Table 1 Basic physical parameters of cores used in the experiment |
| 岩心编号 | 长度 /cm | 直径 /cm | 干重/g | 渗透率 /(10-3 μm2) | 孔隙度 /% |
|---|---|---|---|---|---|
| C7-2 | 5.199 | 2.419 | 56.89 | 0.057 7 | 7.75 |
| C7-4 | 5.243 | 2.422 | 56.734 | 0.097 1 | 8.36 |
| C7-6 | 5.086 | 2.419 | 56.34 | 0.048 1 | 7.19 |
| C7-8 | 5.403 | 2.417 | 56.676 | 0.067 2 | 7.85 |
| C7-10 | 4.952 | 2.421 | 55.029 | 0.080 3 | 8.12 |
| C8-2 | 6.254 | 2.38 | 61.101 | 4.993 | 8.73 |
| C8-4 | 5.293 | 2.4 | 58.976 | 0.022 4 | 4.44 |
| C8-9 | 5.864 | 2.413 | 62.353 | 0.381 | 6.19 |
| C8-10 | 5.57 | 2.416 | 58.877 | 0.257 | 7.87 |
| C8-12 | 4.865 | 2.419 | 49.951 | 3.548 | 8.89 |
| C8-13 | 4.589 | 2.422 | 49.661 | 1.052 | 8.35 |
| S2-151 | 3.241 | 2.544 | 43.989 | 0.001 693 | 1.05 |
| S2-175 | 3.186 | 2.477 | 40.937 | 0.000 037 | 1.18 |
| S2-166 | 3.185 | 2.514 | 42.325 | 0.000 556 | 0.81 |
| S2-168 | 3.236 | 2.514 | 40.321 | 0.000 624 | 0.92 |
| H8-131 | 2.295 | 2.539 | 31.046 | 0.000 027 | 0.99 |
| H8-133 | 3.069 | 2.544 | 41.378 | 0.000 022 | 1.67 |
| H8-162 | 3.024 | 2.532 | 40.185 | 0.000 271 | 1.46 |
| H8-173 | 3.058 | 2.367 | 35.75 | 0.000 692 | 1.52 |
1.2 实验设计
2 油藏中CO2置换实验
2.1 CO2置换实验
2.1.1 注气量和渗透率对CO2置换效率的影响
表2 不同岩心相同焖井时间(12 h)后的CO2置换效率测试结果Table 2 Test results of CO2 replacement efficiency of different cores after the same simmering time (12 h) |
| 岩心编号 | 渗透率/(10-3 μm2) | 降压返排 | 注气反驱油量/mL | 置换效率/% | |
|---|---|---|---|---|---|
| 油量/mL | 气量/mL | ||||
| C7-2 | 0.057 7 | 0.138 | 700 | 0.068 | 17.80 |
| C7-4 | 0.097 1 | 0.207 | 650 | 0.063 | 18.19 |
| C7-6 | 0.048 1 | 0.122 | 615 | 0.045 | 15.38 |
| C7-8 | 0.067 2 | 0.159 | 620 | 0.058 | 17.92 |
| C7-10 | 0.080 3 | 0.192 | 655 | 0.062 | 18.01 |
| C8-2 | 4.993 | 0.757 | 283 | 0.179 | 45.48 |
| C8-4 | 0.022 4 | 0.117 | 98 | 0.036 | 15.52 |
| C8-9 | 0.381 | 0.12 | 203 | 0.214 | 25.04 |
| C8-10 | 0.257 | 0.338 | 193 | 0.071 | 17.54 |
| C8-12 | 3.548 | 0.453 | 198 | 0.433 | 45.72 |
| C8-13 | 1.052 | 0.247 | 156 | 0.312 | 41.32 |
|
图2 C7储层相同渗透率级别岩心焖井时间12 h的CO2焖井置换效率Fig.2 CO2 simmering efficiency of core simmering time of 12 h in C7 reservoir with the same permeability level |
2.1.2 焖井时间对CO2置换效率的影响
图4 C7储层相同渗透率级别岩心不同焖井时间的置换效率Fig.4 Replacement efficiency of cores in C7 reservoir with the same permeability level and different simmer time |
图5 C8储层相同渗透率级别岩心不同焖井时间的置换效率Fig.5 Replacement efficiency of cores in C8 reservoir with the same permeability level and different simmer time |
表3 C7、C8油藏岩心CO2置换效率与不同焖井时间实验结果Table 3 CO2 replacement efficiency and different simmer time experimental results of cores in C7 and C8 reservoirs |
| 焖井时间/h | C7油藏 | C8油藏 | ||||||
|---|---|---|---|---|---|---|---|---|
| 降压返排 | 注气反驱 油量/mL | 置换效率/% | 降压返排 | 注气反驱 油量/mL | 置换效率/% | |||
| 油量/mL | 气量/mL | 油量/mL | 气量/mL | |||||
| 6 | 0.124 | 720 | 0.07 | 16.77 | 0.28 | 205 | 0.102 | 22.03 |
| 12 | 0.138 | 700 | 0.068 | 17.8 | 0.32 | 203 | 0.114 | 25.03 |
| 24 | 0.145 | 685 | 0.072 | 18.76 | 0.361 | 189 | 0.104 | 26.82 |
| 48 | 0.151 | 669 | 0.069 | 19.01 | — | — | — | — |
2.2 XRD矿物成分分析
表4 油藏岩心中CO2置换前后沉积岩X-射线衍射分析结果Table 4 X-ray diffraction analysis results of sedimentary rocks before and after CO2 replacement in the core of the reservoir |
| 区块 | 石英/% | 钾长石/% | 斜长石/% | 白云石/% | 方解石/% | 黄铁矿/% | 黏土矿物/% | 备注 |
|---|---|---|---|---|---|---|---|---|
| C7 | 50.6 | 7.1 | 22.4 | 1.9 | 3.6 | 0.0 | 14.3 | 置换前 |
| 60.2 | 8.2 | 16.2 | 0.0 | 2.1 | 0.0 | 13.3 | 置换6 h | |
| 59.7 | 4.4 | 18.2 | 0.0 | 3.3 | 0.0 | 14.4 | 置换12 h | |
| 55.2 | 9.7 | 17.3 | 2.1 | 2.4 | 0.0 | 13.3 | 置换24 h | |
| C8 | 29.4 | 14.9 | 36.0 | 0.0 | 5.0 | 0.0 | 14.7 | 置换前 |
| 25.2 | 19.5 | 41.9 | 0.0 | 1.0 | 0.0 | 12.4 | 置换6 h | |
| 25.1 | 16.2 | 37.1 | 0.0 | 4.5 | 0.0 | 17.1 | 置换12 h | |
| 40.2 | 11.6 | 30.1 | 0.0 | 1.6 | 0.0 | 16.5 | 置换24 h |
2.3 SEM微观孔喉结构影响
3 气藏中CO2置换实验
3.1 CO2置换实验
图7 S2气藏S2-168岩心不同焖井时间CO2置换效率Fig.7 CO2 replacement efficiency at different simmering time of S2-168 cores in S2 gas reservoir |
图8 H8气藏H8-162岩心不同焖井时间CO2置换效率Fig.8 CO2 replacement efficiency at different simmering times of H8-162 cores in H8 gas reservoir |
表5 不同数量级渗透率岩心相同焖井时间(12 h)后的CO2置换效率测试结果Table 5 Test results of CO2 replacement efficiency of cores with different magnitudes of permeability after the same simmer time (12 h) |
| 岩心编号 | 渗透率/(10-3 μm2) | 饱和甲烷量/mL | CO2注入量/mL | 降压返排气量 /mL | 置换效率/% |
|---|---|---|---|---|---|
| S2-151 | 0.001 693 | 1.105 | 0.21 | 302 | 79.28 |
| S2-175 | 0.000 037 | 1.098 | 0.23 | 283 | 72.97 |
| S2-166 | 0.000 556 | 1.078 | 0.18 | 275 | 76.23 |
| H8-131 | 0.000 027 | 1.125 | 0.25 | 319 | 79.03 |
| H8-133 | 0.000 022 | 1.07 | 0.21 | 287 | 77.2 |
| H8-173 | 0.000 692 | 1.132 | 0.24 | 298 | 74.29 |
3.2 XRD矿物成分分析
表6 气藏岩心中CO2置换前后沉积岩X-射线衍射分析结果Table 6 X-ray diffraction analysis results of sedimentary rocks before and after CO2 replacement in the cores of gas reservoirs |
| 岩心编号 | 石英/% | 钾长石/% | 斜长石/% | 白云石/% | 方解石/% | 黄铁矿/% | 黏土矿物/% | 备注 |
|---|---|---|---|---|---|---|---|---|
| H8-162 | 0.4 | 0.0 | 0.0 | 1.4 | 98.1 | 0.1 | 0.0 | 置换前 |
| 0.3 | 0.0 | 0.0 | 1.3 | 98.4 | 0.0 | 0.0 | 置换12 h | |
| S2-168 | 0.3 | 0.0 | 0.0 | 0.0 | 89.9 | 0.0 | 9.8 | 置换前 |
| 0.0 | 0.0 | 0.0 | 0.0 | 93.0 | 0.9 | 6.0 | 置换12 h |

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