0 前言
1 地质背景
2 页岩生气潜力
3 页岩储层发育特征
3.1 储层矿物组成
表1 川东北地区中—上二叠统页岩主要矿物组成特征Table 1 Main mineral composition characteristics of the Middle-Upper Permian shales in northeastern Sichuan Basin |
| 层位 | 矿物组成/% | 脆性指数/% | ||
|---|---|---|---|---|
| 硅质矿物 | 黏土矿物 | 碳酸盐矿物 | ||
| 大一段 | 4.00~95.0/49.80 | 0~55.25/18.32 | 2~96.00/28.50 | 39.58~100/80.70 |
| 吴三段 | 6.35~90.56/48.80 | 2.21~64.83/17.36 | 0~73.12/33.13 | 0~100/76.54 |
| 孤峰组 | 0~82.50/47.09 | 1.30~23.40/7.46 | 4.90~94.0/37.67 | 49.3~97/84.76 |
注:表中数据表达方式为最小值~最大值/平均值。 |
3.2 孔隙类型及特征
3.2.1 孔隙类型
3.2.2 孔隙结构及孔径分布
表2 川东北地区中—上二叠统3套页岩关键地质参数Table 2 Key geological parameters of the three shale formations of the Middle-Upper Permian in northeastern Sichuan Basin |
| 参数 | 孤峰组 | 吴三段 | 大一段 |
|---|---|---|---|
| TOC/% | 0.76~27.10/9.82 | 0.30~20.98/6.60 | 0.71~15.50/6.01 |
| Ro/% | 1.85~2.54/2.34 | 1.88~3.32/2.53 | 2.02~2.22/2.16 |
| δ13C/‰ | -28~-26 | -28~-26 | -28.04~-25.15 |
| 有机质类型 | II1 | II1 | II1 |
| 孔隙度/% | 3.31~6.12/4.75 | 3.71~7.56/5.08 | 0.39~4.71/2.47(LY1井) |
| 0.04~6.25/2.49(YWD1井) | |||
| 0.04~8.34/2.53(HD1井) | |||
| 孔隙度优势区间(占比/%) | 4~6(87.5%) | 4~6(85.7%) | 0~2(85.7%) |
| 0~2(74.2%) | |||
| 0~2(84.0%) | |||
| 渗透率/(×10-3μm2) | 0.000 11~0.007/0.001 59 | 0.056 9~1.42/0.586 0 | 0.000 449~0.808/0.034 |
| 比表面积/(m2•g-1) | 3.90~55.61/30.11 | 6.63~33.12/18.76 | 4.44~69.89/22.76 |
| 比表面积占比/% | 微孔 25.38~63.28/45.91 | 微孔20.50~41.60/30.70 | 微孔17.09~55.81/38.72 |
| 介孔 36.30~72.07/53.00 | 介孔57.80~78.40/67.50 | 介孔43.48~76.89/59.52 | |
| 宏孔 0.41~2.55/1.09 | 宏孔 0.60~5.10/1.80 | 宏孔 0.61~6.56/1.75 | |
| 孔体积/(cm3•g-1) | 0.012 1~0.040 7/0.025 5 | 0.015~0.047/0.031 2 | 0.003 9~0.051 1/0.023 0 |
| 孔体积占比/% | 微孔 4.86~35.84/19.01 | 微孔 3.45~17.50/8.76 | 微孔 2.92~23.72/12.31 |
| 介孔 50.44~69.38/61.74 | 介孔56.44~79.44/69.18 | 介孔59.53~71.20/64.99 | |
| 宏孔 12.78~28.43/19.25 | 宏孔13.65~40.12/22.06 | 宏孔14.41~36.57/22.70 | |
| 连通系数 | 0.75~5.21/2.57 | 2.01~8.49/5.17 | 0.81~2.87/1.69 |
注:表中数据表达方式为最小值~最大值/平均值。 |
3.2.3 页岩孔隙连通性
3.3 储层物性
3.4 储层含气性
4 地质意义
表3 川东北中—上二叠统3套页岩与川南龙马溪组页岩储层参数对比Table 3 Comparison of shale reservoir parameters of three shale formations of the Middle-Upper Permian in northeastern Sichuan Basin with the Longmaxi shale in southern Sichuan Basin |
| 地层 | 区块 | TOC/% | 孔隙度/% | 脆性矿物/% | Ro/% | 厚度/m | 埋深/m | 含气量/(m3·t-1) |
|---|---|---|---|---|---|---|---|---|
| 大一段 | 川东北 | 0.71~15.50 | 1.30~5.70 | 59~100 | 2.0~2.2 | 20~45 | 1 000~8 000 | 0.60~9.92 |
| 吴三段 | 0.30~20.98 | 3.15~6.80 | 69~94 | 2.0~2.8 | 20~60 | 2 000~8 000 | 0.49~16.16 | |
| 孤峰组 | 0.76~27.10 | 3.31~6.12 | 76.6~98.7 | 2.3~3.0 | 5~25 | 3 000~8 000 | 0.45~12.70 | |
| 龙马溪组[33] | 泸州 | 2.80~3.30 | 4.40~5.70 | 55~72 | 2.3~3.0 | 32~65 | 3 000~4 500 | 2.90~4.60 |
| 长宁 | 3.60~4.40 | 3.50~7.00 | 66~80 | 2.3~2.9 | 25~35 | 4 000~4 500 | 5.00~7.50 | |
| 渝西 | 3.00~3.20 | 3.40~5.90 | 52~68 | 1.8~3.0 | 29~66 | 2 000~4 000 | 3.60~5.70 | |
| 威远 | 4.16~7.70 | 4.50~7.50 | 83~100 | 1.8~3.0 | 20~45 | 1 500~4 000 | 2.40~7.34 |
图12 川东北中—上二叠统页岩气勘探有利区分布图(吴三段有利区引自[10,12],大一段有利区引自[11,14],有修改)Fig. 12 Distribution map of prospective areas for shale gas exploration of the Middle-Upper Permian in northeastern Sichuan Basin (prospective areas for P3w3 cited from reference[10,12], prospective areas for P3d1 cited from reference[11,14], modified)) |
