一种页岩有机孔与无机孔定量表征的方法

doi:10.13809/j.cnki.cn32-1825/te.2020.01.005

摘要/Abstract

摘要：

扫描电镜图像处理后得到的面孔率结果能够有效反映页岩有机质孔隙的发育程度,在统计样本足够大的前提下能够相对准确地定量表征有机质孔隙的规模大小。由于受扫描电镜绝对分辨率的限制,面孔率结果在小于2 nm的孔径范围内低估了有机孔含量,需要通过吸附法得到的孔径分布结果进行校正,再结合TOC和有效孔隙度来计算页岩有机质孔隙度,从而间接得到有机孔和无机孔比例。渝东南地区4口页岩气井的数据表明武隆和东胜地区以有机孔为主,底部①至②小层的有机孔比例高,最高可达85.89 %;彭水地区受有机碳控制,有机孔比例不高于20 %;平桥地区有机孔比例在20 %~30 % ,层理缝及纹层构造相对发育,尤其是纹层构造中碎屑颗粒与泥质互层间可能存在的裂隙或粒缘缝对无机孔的贡献较大。有机孔比例主要受有机质丰度与有机质孔隙发育程度的影响,有机孔比例与TOC含量在纵向上的变化规律高度一致。

关键词: 页岩, 孔隙, 有机孔, 无机孔, 定量

Abstract:

The results of surface porosity obtained by scanning electron microscopy image processing can effectively reflect the development degree of shale organic matter pore. On the premise that the statistical sample is large enough, the pore size of organic matter can be quantitatively characterized relatively accurately. Due to the limitation of absolute resolution of scanning electron microscopy, the organic pore content was underestimated in the pore size range of less than 2 nm. The results of pore size distribution obtained by adsorption method need to be corrected. Combined with TOC and effective porosity, the porosity of shale organic matter can be calculated, and the proportion of organic and inorganic pore can be obtained indirectly. The data of 4 shale gas wells in southeastern Chongqing show that organic pore is the main type in Wulong and Dongsheng area, and the proportion of organic pore in bottom layer（① to ②） is high, up to 85.89 %. Pengshui area is controlled by organic carbon, and the proportion of organic pore is not more than 20 %. The organic pore proportion in Pingqiao area ranges from 20 % to 30 %, and the bedding fissures and laminar structures are relatively developed, especially the possible fissures or grain margin fissures between clastic particles and muddy interbeds in laminar structures contribute greatly to the inorganic pore. The proportion of organic pore is mainly affected by the abundance of organic matter and the degree of pore development of organic matter. The ratio of organic pore is highly consistent with the variation of TOC content in the vertical direction.

Key words: shale, pore, organic pore, inorganic pore, quantify

中图分类号:

TE135

蔡潇,靳雅夕,叶建国,彭柳,孙婧榕,朱一川. 一种页岩有机孔与无机孔定量表征的方法[J]. 油气藏评价与开发, 2020, 10(1): 30-36.

CAI Xiao,JIN Yaxi,YE Jianguo,PENG Liu,SUN Jingrong,ZHU Yichuan. A quantitative characterization method for organic and inorganic pores in shale[J]. Reservoir Evaluation and Development, 2020, 10(1): 30-36.

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井号	含气量/（cm³·g^-1）	孔隙度/%	TOC/%	镜质体反射率/%	石英/%	黏土矿物/%	长石/%	碳酸盐矿/%	黄铁矿等/%	压力系数
A井	1.82	2.51	2.74	2.64	45.5	28.5	11.7	9.8	4.5	0.96
B井	2.16	4.88	4.11	2.57	54.0	25.3	10.2	6.5	4.4	1.08
C井	3.00	3.68	3.40	3.01	50.4	32.7	6.6	6.2	4.5	1.30
D井	2.94	4.47	3.00	2.71	49.2	30.0	6.5	7.0	3.8	1.20

层号	井号
层号	A井	B井	C井	D井
⑤小层	3.30	13.73	8.88	28.42
④小层	5.88	16.71	8.44	14.70
③小层	7.26	15.50	9.64	13.31
②小层	7.63	13.64	4.16	22.91
①小层	5.90	13.00	5.95	20.69

层号	井号
层号	A井	B井	C井	D井
⑤小层	4.08	19.53	13.62	38.88
④小层	6.74	23.70	11.93	19.81
③小层	8.04	24.66	14.11	17.58
②小层	8.34	22.74	5.94	24.12
①小层	6.45	18.89	8.22	26.77

层号	井号
层号	A井	B井	C井	D井
⑤小层	0.13	1.14	0.81	2.42
④小层	0.38	2.92	0.82	1.43
③小层	0.58	3.19	1.01	1.19
②小层	0.60	3.64	0.84	4.45
①小层	0.47	2.22	0.81	3.00