scholarly journals Characteristics of Organic Matter Particles and Organic Pores of Shale Gas Reservoirs: A Case Study of Longmaxi-Wufeng Shale, Eastern Sichuan Basin

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 137
Author(s):  
Guochang Wang ◽  
Shengxiang Long ◽  
Yongmin Peng ◽  
Yiwen Ju
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Sichuan Basin ◽  
Pore System ◽  
Gas Reservoirs ◽  
Sem Images ◽  
Eastern Sichuan Basin ◽  
Eastern Sichuan ◽  
Organic Porosity ◽  
Organic Pores

Heterogeneity of organic matter (OM), including size, type, and organic pores within OM, is being recognized along with increasing study using SEM images. Especially, the contribution of organic pores to the entire pore system should be better understood to aid in the evaluation of shale reservoirs. This research observed and quantitatively analyzed over 500 SEM images of 19 core samples from Longmaxi-Wufeng Shale in the eastern Sichuan Basin to summarize the features of OM particles and OM-hosted pores and their evolution during burial. The features of organic pores as well as the embedded minerals within OM particles enables to recognize four different type of OM particles. The organic pore features of each type of OM particles were quantitatively described using parameters such as pore size distribution (PSD), pore geometry, and organic porosity. The PSD of weakly or undeformed porous pyrobitumen indicates that the large organic pores (usually 200 nm to 1 um) is less common than small pores but the major contributor to organic porosity. The organic porosity of OM particles covers a large range of 1–35%, indicating a high heterogeneity among OM particles. Based on analysis of 81 OM particles, the average of organic porosity of the five samples were calculated and ranges from 3% to 12%. In addition, samples from well JY1 have higher organic porosity than JY8. These results helped to reveal how significant the organic pores are for shale gas reservoirs. In addition to presenting many examples of OM particles, this research should significantly improve the understanding of type and evolution of OM particles and contribution of OM-hosted pores to the entire pore system of high to over mature shale.

Organic matter-hosted pore system in the Wufeng-Longmaxi (O 3 w-S 1 1) shale, Jiaoshiba area, Eastern Sichuan Basin, China

2017 ◽  
Vol 173 ◽  
pp. 40-50 ◽  
Author(s):  
Haiyan Hu ◽  
Fang Hao ◽  
Junfeng Lin ◽  
Yongchao Lu ◽  
Yiquan Ma ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sichuan Basin ◽  
Pore System ◽  
Eastern Sichuan Basin ◽  
Eastern Sichuan

Geological controls and methane sorption capacity of marine shales of the Fuling shale gas field in the eastern Sichuan Basin, China

2017 ◽  
Vol 23 (4) ◽  
pp. 466-475 ◽  
Author(s):  
Xiaoming Zhang ◽  
Wanzhong Shi ◽  
Qinhong Hu ◽  
Shiwan Zhang ◽  
Haiyan Hu ◽  
...  
Keyword(s):  
Sorption Capacity ◽  
Shale Gas ◽  
Sichuan Basin ◽  
Gas Field ◽  
Eastern Sichuan Basin ◽  
Methane Sorption ◽  
Eastern Sichuan

Shale-gas reservoir-prediction study in Daanzhai, Eastern Sichuan Basin

2014 ◽  
Vol 33 (5) ◽  
pp. 526-534 ◽  
Author(s):  
Zhongping Li ◽  
Fangyan Huang ◽  
Xinwei He ◽  
Wanlong Zhang ◽  
Yuting He
Keyword(s):  
Shale Gas ◽  
Sichuan Basin ◽  
Reservoir Prediction ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Eastern Sichuan Basin ◽  
Eastern Sichuan

scholarly journals Differences of Main Enrichment Factors of S1l11-1 Sublayer Shale Gas in Southern Sichuan Basin

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5472
Author(s):  
Xuewen Shi ◽  
Chao Luo ◽  
Gaohui Cao ◽  
Yifan He ◽  
Yi Li ◽  
...  
Keyword(s):  
Shale Gas ◽  
Sichuan Basin ◽  
Mineral Content ◽  
Enrichment Factors ◽  
Gas Content ◽  
Longmaxi Formation ◽  
The Difference ◽  
Organic Porosity ◽  
Gas Bearing ◽  
Organic Pores

In this study, shale cores from 20 wells in the S1l11-1 sublayer of Longmaxi Formation buried in shallow shale (<3500 m) and deep shale (>3500 m) in the southern Sichuan Basin, China were collected to compare their pore structures and gas-bearing properties using multiple experiments. Results showed that the deep layer has relatively lower brittle mineral content, which is disadvantageous in terms of the higher requirements it imposes on hydraulic fracturing. Results also showed that the most important factor controlling the differential enrichment of S1l11-1 shale gas in southern Sichuan Basin is porosity. Moreover, the porosity composition of shallow shale and deep shale has significant differences: the porosity of shallow shale is dominated by organic pores, while for deep shale, both organic and inorganic pores are important. The inorganic pores provide significant storage space for free gas in deep shale; their contribution warrants more attention. We also found that the difference in organic porosity of the shallow and deep shale samples resulted from large differences in pore development ability, while the highest inorganic porosity was concentrated near the optimal mineral composition when the content of quartz plus feldspar plus pyrite was about 70%. This study revealed the primary factor controlling the difference in gas content between shallow and deep shale and detailed the characteristics of microscopic pore structure, providing a basis for the exploration and development of deep shale gas in the Wufeng-Longmaxi Formation in the southern Sichuan Basin.

scholarly journals Coevolutionary Dynamics of Organic-Inorganic Interactions, Hydrocarbon Generation, and Shale Gas Reservoir Preservation: A Case Study from the Upper Ordovician Wufeng and Lower Silurian Longmaxi Formations, Fuling Shale Gas Field, Eastern Sichuan Basin

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Zhijun Jin ◽  
Haikuan Nie ◽  
Quanyou Liu ◽  
Jianhua Zhao ◽  
Ruyue Wang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Sichuan Basin ◽  
Hydrocarbon Generation ◽  
Upper Ordovician ◽  
Gas Field ◽  
Pressure System ◽  
Lower Silurian ◽  
Eastern Sichuan Basin ◽  
Eastern Sichuan

Shale gas deposits are self-sourced, self-accumulating, and self-preserving in the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation of the Fuling Shale Gas Field in the eastern Sichuan Basin. They were both seemingly mixed by secondary oil cracking and kerogen cracking gases during the high maturation window. The reservoir space primarily consists of mineral pores and organic matter (OM) pores, and the shale gas was mainly trapped by a high-pressure system. In this study, the Fuling O3w-S1l Shale Gas Field in the eastern Sichuan Basin was used as a case study to discuss the coevolutionary process and organic-inorganic interactions of hydrocarbon generation, accumulation, and preservation. The results indicate that the processes and mechanisms of organic-inorganic interactions and coevolution of hydrocarbon generation and reservoir preservation are quite different among the shale graptolite zones (GZ) with respect to hydrocarbon generation, types and characteristics of shale gas reservoirs, seal characteristics, and their spatiotemporal relations. In the WF2-LM4 GZ, the favorable OM, biogenic authigenic quartz and organic-inorganic interactions are highly coupled, leading to the high level of coevolution demonstrated within the field, as well as to the favorable conditions for shale gas accumulation. Conversely, the overlying LM5-LM8 GZ seemingly exhibits early densification and late charge and has a reverse mode of reservoir development (i.e., low degree of coevolution). These two coevolutionary processes were conducive to the development of a high degree of spatiotemporal matching between the reservoir (i.e., WF2-LM4 GZ) and the seal (i.e., LM5-LM8 GZ). This is due to underlying differences in their coevolutionary histories. The synthetic work presented here on the coevolutionary processes and mechanisms of formation for organic-inorganic interactions and hydrocarbon generation and reservoir preservation reveals insights into the driving mechanisms of shale gas enrichment, providing a basis for effectively predicting favorable enrichment intervals for shale gas worldwide.

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