Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas Enrichment

The Silurian Longmaxi (S<sub>1</sub>l) marine shale and Jurassic Dongyuemiao (J<sub>1</sub>d) lacustrine shale in the Sichuan Basin, West China have attracted considerable attention from the oil-and-gas industry in China. Currently, the differences in pore types and pore stru...

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Main Authors: Pengwei Wang, Haikuan Nie, Zhongbao Liu, Chuanxiang Sun, Zhe Cao, Ruyue Wang, Pei Li
Format: Article
Language:English
Published: MDPI AG 2023-01-01
Series:Minerals
Subjects:
Online Access:https://www.mdpi.com/2075-163X/13/2/190
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author Pengwei Wang
Haikuan Nie
Zhongbao Liu
Chuanxiang Sun
Zhe Cao
Ruyue Wang
Pei Li
author_facet Pengwei Wang
Haikuan Nie
Zhongbao Liu
Chuanxiang Sun
Zhe Cao
Ruyue Wang
Pei Li
author_sort Pengwei Wang
collection DOAJ
description The Silurian Longmaxi (S<sub>1</sub>l) marine shale and Jurassic Dongyuemiao (J<sub>1</sub>d) lacustrine shale in the Sichuan Basin, West China have attracted considerable attention from the oil-and-gas industry in China. Currently, the differences in pore types and pore structures between them are poorly understood, which has limited shale-resource exploration in the Sichuan Basin. This paper systemically compares the pore characteristics of Longmaxi shale and Dongyuemiao shale and investigates their impact on shale-gas enrichment by integrating field-emission scanning electron microscopy (FE–SEM), X-ray diffraction (XRD), low-pressure gas (CO<sub>2</sub> and N<sub>2</sub>) adsorption and mercury-intrusion porosimetry, high-pressure sorption isotherms, gas-saturation measurement, molecular-dynamics simulation, etc. The results show that the S<sub>1</sub>l organic-rich marine shale and the J<sub>1</sub>d lacustrine shale have different pore types and pore structures. The S<sub>1</sub>l shale is dominated by organic pores, mainly micropores and mesopores with ink-bottle-like pore shapes, while the J<sub>1</sub>d shale is primarily composed of clay-mineral pores, mainly mesopores and macropores with slit- or plate-like pore shapes. Organic pores can provide considerable storage space for shale-gas enrichment in S<sub>1</sub>l marine shale, which also determines the adsorption capacity of shale reservoirs. Although organic pores are not the most prevalent in the Dongyuemiao lacustrine shale, they also play an important role in enhancing reservoir quality and absorbed-gas enrichment. Clay-mineral pores contribute weakly to the storage space of J<sub>1</sub>d-lacustrine-shale reservoirs. Mesopores are the most important form of storage space in both S<sub>1</sub>l shale and J<sub>1</sub>d shale, contributing significantly to shale-gas enrichment. Micropores are secondary in importance in S<sub>1</sub>l marine shale, while macropores are secondary contributors to pore volume in J<sub>1</sub>d lacustrine shale.
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spelling doaj.art-b5856955209d4c2d9725fca6812fec772023-11-16T22:18:07ZengMDPI AGMinerals2075-163X2023-01-0113219010.3390/min13020190Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas EnrichmentPengwei Wang0Haikuan Nie1Zhongbao Liu2Chuanxiang Sun3Zhe Cao4Ruyue Wang5Pei Li6Research Institute of Petroleum Exploration & Production, SINOPEC, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Production, SINOPEC, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Production, SINOPEC, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Production, SINOPEC, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Production, SINOPEC, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Production, SINOPEC, Beijing 100083, ChinaResearch Institute of Petroleum Exploration & Production, SINOPEC, Beijing 100083, ChinaThe Silurian Longmaxi (S<sub>1</sub>l) marine shale and Jurassic Dongyuemiao (J<sub>1</sub>d) lacustrine shale in the Sichuan Basin, West China have attracted considerable attention from the oil-and-gas industry in China. Currently, the differences in pore types and pore structures between them are poorly understood, which has limited shale-resource exploration in the Sichuan Basin. This paper systemically compares the pore characteristics of Longmaxi shale and Dongyuemiao shale and investigates their impact on shale-gas enrichment by integrating field-emission scanning electron microscopy (FE–SEM), X-ray diffraction (XRD), low-pressure gas (CO<sub>2</sub> and N<sub>2</sub>) adsorption and mercury-intrusion porosimetry, high-pressure sorption isotherms, gas-saturation measurement, molecular-dynamics simulation, etc. The results show that the S<sub>1</sub>l organic-rich marine shale and the J<sub>1</sub>d lacustrine shale have different pore types and pore structures. The S<sub>1</sub>l shale is dominated by organic pores, mainly micropores and mesopores with ink-bottle-like pore shapes, while the J<sub>1</sub>d shale is primarily composed of clay-mineral pores, mainly mesopores and macropores with slit- or plate-like pore shapes. Organic pores can provide considerable storage space for shale-gas enrichment in S<sub>1</sub>l marine shale, which also determines the adsorption capacity of shale reservoirs. Although organic pores are not the most prevalent in the Dongyuemiao lacustrine shale, they also play an important role in enhancing reservoir quality and absorbed-gas enrichment. Clay-mineral pores contribute weakly to the storage space of J<sub>1</sub>d-lacustrine-shale reservoirs. Mesopores are the most important form of storage space in both S<sub>1</sub>l shale and J<sub>1</sub>d shale, contributing significantly to shale-gas enrichment. Micropores are secondary in importance in S<sub>1</sub>l marine shale, while macropores are secondary contributors to pore volume in J<sub>1</sub>d lacustrine shale.https://www.mdpi.com/2075-163X/13/2/190pore typespore structuremarine shalelacustrine shaleSichuan Basin
spellingShingle Pengwei Wang
Haikuan Nie
Zhongbao Liu
Chuanxiang Sun
Zhe Cao
Ruyue Wang
Pei Li
Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas Enrichment
Minerals
pore types
pore structure
marine shale
lacustrine shale
Sichuan Basin
title Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas Enrichment
title_full Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas Enrichment
title_fullStr Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas Enrichment
title_full_unstemmed Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas Enrichment
title_short Differences in Pore Type and Pore Structure between Silurian Longmaxi Marine Shale and Jurassic Dongyuemiao Lacustrine Shale and Their Influence on Shale-Gas Enrichment
title_sort differences in pore type and pore structure between silurian longmaxi marine shale and jurassic dongyuemiao lacustrine shale and their influence on shale gas enrichment
topic pore types
pore structure
marine shale
lacustrine shale
Sichuan Basin
url https://www.mdpi.com/2075-163X/13/2/190
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