Preliminary study on nanopores, nanofissures, and in situ accumulation of Gulong shale oil

doi:10.13745/j.esf.sf.2022.8.32

Abstract

Abstract:

The shale oil resource in the Qingshankou formation, Gulong Sag amounts to 15.1 billion tons, making it an important petroleum “backup” resource. Electron backscattering (HDBSD) shows that nm pores and fissures are well developed in the Gulong shale oil reservoir. The nm pores are mostly 10-50 nm in diameter (median 20-30 nm) and have irregular or polygonal shapes. They are mainly a kind of E-F nano holes, and some E-E nano pores, and connected to the nano fissures that have slit widths mostly between 10-50 nm (median 20-30 nm). The nm fissures are mainly formed in clays via F-F condensation. Clay coagulation is closely related to organic matter, especially algae. The clay colloid is negatively charged due to isocrystalline replacement, and metal cations are absorbed around it to form a positive clay group. The positively charged clays in turn adsorb the negatively charged humic acid (organic matter) and lightly degraded algae to form an organic clay flocculant. When the organic clay flocculates reach the hydrocarbon generation/release threshold, organic matter shrinks up to 87% in volume. Due to capillary resistance (~12 MPa) from nano fissures, the discharged hydrocarbon cannot migrate out, thus forming the special continuous in-situ shale oil reservoir of Gulong.

Key words: shale, clay, organic matter, nano-pore and nano-fissure, in-situ accumulation, Gulong Sag

CLC Number:

P618.130.2

HE Wenyuan. Preliminary study on nanopores, nanofissures, and in situ accumulation of Gulong shale oil[J]. Earth Science Frontiers, 2023, 30(1): 156-173.

Figures/Tables 21

Fig.1 Structural zoning and location map of the study area. Modified after [1].

Fig.2 East-west seismic profile of Gulong Sag in Songliao Basin and its interpretation. Modified after [1].

Fig.3 Strata columnar in the study area. Modified after [1].

Fig.4 Microstructure or fabric of Gulong shale of Qingshankou Formation

Fig.5 Arrangement of clay-organic aggregate and its particles

Fig.6 Algal debris-clay aggregates

Fig.7 Organic carbon distribution of 4 Wells in Qingshankou Formation of Gulong Sag

Fig.8 Backscattering diagram and energy spectrum diagram of the Qing 1 section of Guye 3HC well

Fig.9 Histogram of energy spectrum analysis

Table 1 Analysis results of energy spectrum of the Qing 1 section of Guye 3HC well

点号	w_B/%
点号	C	O	Na	Mg	Al	Si	K	Fe
70	41.12	21.54	0.31	0.61	9.31	17.56	5.15	2.31
71	35.66	23.55	0.30	0.58	10.95	20.03	5.79	2.55
72	40.83	13.53	0.33	0.58	11.13	22.84	7.19	3.02
73	50.95	20.26	0.83	0.35	5.56	15.22	2.42	1.66
74	56.44	18.07	0.89	0.25	4.19	12.99	1.72	2.18
75	26.41	32.72	4.84		7.50	23.59	0.26	3.63
76	16.99	33.35	4.11		10.53	32.09	2.08	0.85
77	60.47	12.55	1.11	0.12	3.12	13.24	0.98	5.39
78	41.42	16.36			2.08	37.15	2.34	0.65
79	31.26	19.41	0.54	0.55	8.05	34.64	3.78	1.77
82	72.24	15.66	0.46	0.13	1.70	6.56	0.82	0.74
80	31.84	19.42	0.28	0.81	11.65	27.72	5.78	2.50
81	82.69	10.77	0.68		0.63	2.17	0.24	0.36
83	44.19	21.45	0.51	1.21	6.72	13.73	3.43	3.68
84	53.87	21.30	0.39	0.39	5.33	13.99	2.78	1.31
85	80.18	7.19	0.29	0.14	2.39	5.72	1.29	1.26
86	91.46	0.21	1.51	3.70	0.44	0.05	0.76	1.36
87	89.24		0.28	0.12	1.80	4.42	0.90	1.21
平均值	52.63	18.08	1.04	0.68	5.73	16.87	2.65	2.02

Fig.10 Nano-fissures and the organic matters in clay

Fig.11 The organic matters (solid bitumen) nano-pores and nano-fissures in the clay

Fig.12 Image analysis of dana-kongna fractures between clay domains

Fig.13 Correlation of the area shrinkage rate of algea and vitrinite with temperature (a) and Ro (b). Modified after [23].

Fig.14 Field mission scanning electron microscopic characteristics of shale of Member 1 of Qingshankou Formation in different hydrocarbon generation simulation stages, Gulong area. Modified after [23].

Fig.15 Nanopore micropores and liquid hydrocarbon filling in kerogen

Fig.16 Schematic diagram of wormlike micro-fissures and organic matter filled in them

Fig.17 Shows the development of a large number of dewatering dessication pores and dessication fissures

Fig.18 (Solid) bitumen in the large nano and micron pores

Fig.19 Correlation between pressurization (a) or resistances (b, c) of shale oil and gas and organic matter Ro in the Gulong area. Modified after [23].

Fig.20 Schematic diagram of Gulong shale oil five stage migration and accumulation system. Modified after [1].

References 31

[1]	何文渊, 崔宝文, 王凤兰, 等. 古龙凹陷青山口组页岩储集空间及其油态的研究[J]. 地质论评, 2022, 68(2): 693-741.
[2]	陈昭年, 陈发景. 松辽盆地反转构造运动学特征[J]. 现代地质, 1996, 10(3): 390-396.
[3]	王广昀, 王凤兰, 蒙启安, 等. 古龙页岩油战略意义及攻关方向[J]. 大庆石油地质与开发, 2020, 39(3): 8-19.
[4]	孙龙德. 古龙页岩油(代序)[J]. 大庆石油地质与开发, 2020, 39(3): 1-7.
[5]	王凤兰, 付志国, 王建凯, 等. 松辽盆地古龙页岩油特征及分类评价[J]. 大庆石油地质与开发, 2021, 40 (5): 144-156.
[6]	崔宝文, 张顺, 付秀丽, 等. 松辽盆地古龙页岩有机层序划分及影响因素[J]. 大庆石油地质与开发, 2021, 40(5): 13-28.
[7]	庞彦明, 张元庆, 蔡敏, 等. 松辽盆地古龙页岩油水平井开发技术经济界线[J]. 大庆石油地质与开发, 2021, 40(5): 134-142.
[8]	王永卓, 王瑞, 代旭, 等. 松辽盆地古龙页岩油箱体开发设计方法[J]. 大庆石油地质与开发, 2021, 40(3): 157-169.
[9]	冯子辉, 霍秋立, 曾花森, 等. 松辽盆地古龙页岩有机组成与有机孔隙形成演化[J]. 大庆石油地质与开发, 2021, 40(5): 40-55.
[10]	KRIZEK R J, EDIL T B, OZAYYDIN I K. Preparation and identification of clay samples with controlled fabric[J]. Engineering Geology, 1975, 9: 13-38. DOI URL
[11]	BENNETT R H, BRYANT W R, KELLER G H. Clay fabric and geotechnical properties of selected submarine cores from the Mississippi Delta[C]//NOAA Professional Perer No.9. Washington:Department of Commerce/NOAA/ERL, 1977: 86.
[12]	BRYANT W R, KELLER G H. Clay fabric of selected submarine sediments: fundamental properties and models[J]. Journal of Sedimentary Research, 1981, 51: 217-232.
[13]	SCHIEBER J, REMUS L, KEVIN B, et al. An SEM study of porosity in the Eagle Ford Shale of Texas: pore types and porosity distribution in a depositional and sequencestratigraphic context[M]//BREYER J A. The Eagle Ford Shale: a renaissance in U. S. oil production. Tulsa: American Association of Petroleum Geologists Memoir, 2016, 110: 167-186.
[14]	BENNETT R H, O’BRIEN N R, HULBERT M H. Determinants of clay and shale microfabric signatures: processes and mechanisms[M]//BENNETT R H, BRYANT W R, HULBERT M H. Microstructure of fine-grained sediments from mud to shale. New York: Springer-Verlag, 1991: 22.
[15]	AVNIMELECH Y, MENZEL R G. Coflocculation of algae and clay to clarify turbid impoundments[J]. Journal of Soil and Water Conservation, 1984, 39(3): 200-203.
[16]	AVNIMELECH Y, TROEGER B W, REED L W. Mutual flocculation of algae and clay: evidence and implications[J]. Science, 1982, 216: 63-65. PMID
[17]	VAN OLPHEN H. An introduction to clay colloid chemistry[J]. Soil Science, 1964, 97(4): 290.
[18]	DEGENS E T. Geochemistry of sediments: a brief survey[M]. New Jersey: Prentice Hall, 1965: 342.
[19]	SWAIN F M. Geochemistry of humus[M]//BREGER I A. Organic geochemistry. New York: Pergamon Press, 1963: 81-147.
[20]	HARE E. Geochemistry of proteins, peptides and amino acids[M]//EGLINTON G, MURPHY M T J. Organic geochemistry: methods and results. Berlin: Springer-Verlag, 1969: 438-63.
[21]	MOON C F, HURST C W. Fabric of muds and shales: an overview[J]. Geological Society London Special Publications, 1984, 15: 579-593. DOI URL
[22]	梁光河. 大陆板块漂移是海底扩张驱动的吗?[C]//中国地球科学联合学术年会论文集. 北京: 中国地球物理学会, 2014: 541.
[23]	何文渊, 蒙启安, 冯子辉, 等. 松辽盆地古龙页岩油原位成藏理论认识及勘探开发实践[J]. 石油学报, 2022, 43(1): 1-13. DOI
[24]	傅容珊, 黄建华, 李力刚, 等. 地球在膨胀吗? 板块运动与地球几何尺度变化[C]//中国地球物理学会第 14 届年会论文集. 西安: 西安地图出版社, 1998: 385.
[25]	GERASIMENKO M D. The problem of the change of the Earth dimension in the light of space geodesy data[M]//SCALERA G, JACOB K H. Why expanding Earth? Berkeley: INGV Publisher, 2003: 395-405.
[26]	孙榕, 申文斌. 由空间大地测量数据探测地球膨胀[C]//中国地球物理学会第26届年会、中国地震学会第13次学术大会论文集. 北京: 地震出版社, 2010: 719-720.
[27]	何永祥. 天然沸石对水体中甲基橙和亚甲基蓝的吸附研究[D]. 郑州: 郑州大学, 2007.
[28]	梁狄刚, 冉隆辉, 戴弹申, 等. 四川盆地中北部侏罗系大面积非常规石油勘探潜力的再认识[J]. 石油学报, 2011, 32(1): 8-17. DOI
[29]	柳波, 吕延防, 冉清昌, 等. 松辽盆地北部青山口组页岩油形成地质条件及勘探潜力[J]. 石油与天然气地质, 2014, 35(2): 280-285.
[30]	金旭, 李国欣, 孟思炜, 等. 陆相页岩油可动用性微观综合评价[J]. 石油勘探与开发, 2021, 48(1): 222-232.
[31]	冯子辉, 柳波, 邵红梅, 等. 松辽盆地古龙地区青山口组泥页岩成岩演化与储集性能[J]. 大庆石油地质与开发, 2020, 39(3): 72-85.