0 引言
1 实验样品和方法
1.1 实验条件
表1 表面活性剂体积浓度及相应界面张力数据Table 1 Volumetric concentration of the surfactant and the corresponding interfacial tension |
TOF-1表面活性剂浓度/% | 与模拟油界面张力/(mN/m) |
---|---|
5 | 0.290 |
0.5 | 1.183 |
0.05 | 3.750 |
0.005 | 10.436 |
表2 实验岩心基础数据Table 2 Basic data of the core used in the experiment |
岩心编号 | 长度/cm | 直径/cm | 孔隙度/% | 渗透率/(10-3 μm2) |
---|---|---|---|---|
木21-2 | 2.360 | 2.508 | 9.81 | 0.159 |
里21-2 | 2.306 | 2.508 | 8.49 | 0.139 |
安25-2 | 0.081 | 2.510 | 8.89 | 0.081 |
1.2 实验方法
2 页岩油储层渗吸置换影响因素
2.1 孔隙半径对渗吸采收率的影响
表3 不同孔隙半径岩心渗吸相对采出程度Table 3 Relative recovery degree of core imbibition with different pore radius |
岩心 编号 | 孔隙度 /% | 渗透率 /(10-3 μm2) | 不同孔隙半径采出程度/% | ||
---|---|---|---|---|---|
小于10 μm | 10~20 μm | 大于20 μm | |||
平均值 | 9.06 | 0.13 | 72.05 | 16.02 | 11.92 |
木21-2 | 9.81 | 0.159 | 74.84 | 12.58 | 12.53 |
里21-2 | 8.49 | 0.139 | 80.94 | 14.55 | 4.52 |
安25-2 | 8.89 | 0.081 | 60.37 | 20.93 | 18.71 |
2.2 界面张力对渗吸采收率的影响
表4 不同界面张力下渗吸采出程度Table 4 The degree of imbibition recovery under different interfacial tension |
助排剂浓度/% | 界面张力/(mN/m) | 渗吸采出程度/% | ||
---|---|---|---|---|
木21-2 | 里21-2 | 安25-2 | ||
5 | 0.290 | 27.169 | 26.376 | 25.747 |
0.5 | 1.183 | 32.320 | 27.483 | 27.473 |
0.05 | 3.750 | 24.662 | 26.430 | 21.641 |
0.005 | 10.436 | 22.495 | 18.349 | 20.730 |
2.3 渗透率对渗吸采收率的影响
图6 长7段页岩油气测渗透率与可动油饱和度、渗吸饱和度、驱替饱和度关系Fig.6 Relationship between gas-measured permeability and movable oil saturation, imbibition saturation and displace-ment saturation of Chang 7 Member shale oil reservoir |
表5 合水地区长7段页岩油不同渗透率区间可动油饱和度Table 5 Movable oil saturation under different permeability intervals of Chang Member 7 shale oil reservoir in Heshui area |
渗透率区间 /(10-3 μm2) | 总可动油饱和度/% | 渗吸可动油饱和度/% | 驱替可动油饱和度/% |
---|---|---|---|
<0.015 | 24.1 | 8.35 | 15.75 |
0.015~0.100 | 35.28 | 9.43 | 25.85 |
0.100~0.200 | 33.67 | 5.29 | 28.39 |
2.4 渗吸作用对驱替采收率的贡献
图7 动态渗吸过程中渗吸及驱替采出量分布Fig.7 Distribution of imbibition and displacement production during dynamic imbibition |
表6 驱替过程中渗吸对采收率的贡献Table 6 Contribution of imbibition to recovery during displacement |
岩心 编号 | 渗透率 /(10-3 μm2) | 驱替速度 /(mL/min) | 焖井 时间/h | 总采收率 /% | 渗吸对采收 率的贡献/% |
---|---|---|---|---|---|
木21-11 | 0.20 | 0.10 | 48 | 70.75 | 23.03 |
木22-11 | 0.18 | 0.05 | 48 | 69.01 | 20.04 |
木22-12 | 0.18 | 0.01 | 48 | 49.64 | 14.70 |
木21-12 | 0.20 | 0.10 | 60 | 67.80 | 33.35 |
木21-12 | 0.20 | 0.10 | 72 | 70.69 | 32.87 |
木27-12 | 0.98 | 0.10 | 48 | 72.11 | 31.83 |
里23-12 | 0.097 | 0.1 | 48 | 61.125 | 40.89 |