Impact of pore structure and fractal characteristics on the sealing capacity of Ordovician carbonate cap rock in the Tarim Basin, China

Jun Wu, Tailiang Fan (Corresponding Author), Enrique Gomez Rivas, Zhiqian Gao, Shuqing Yao, Wenhuan Li, Chenjia Zhang, Qingqing Sun, Yu Gu, Man Xiang

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Evaluating the heterogeneity and sealing capacity of carbonate cap rocks is of great significance for hydrocarbon production. However, the main controls on pore size distribution in carbonate cap rocks are not well constrained. In this contribution we analyze drill core samples of carbonate cap rocks from the Ordovician Yingshan Formation (Tarim Basin) to study their pore properties and investigate the controls of pore-throat structure and fractal dimension on the sealing capacity of the cap rock. Results from petrography and a combination of mercury injection capillary pressure and nitrogen gas adsorption tests reveal that there are four lithological cap rock types, with micrite being the most prevalent one, followed by calcarenite. Six types of pore-throat structures and fractal dimensions (from D1 to D6) are classified based on the pore size distributions, including macropore-I, macropore-II, mesopore-I, mesopore-II, transitional pore-I and transitional pore-II. The fractal dimensions show that there is a decreasing trend from D1 to D6 with decreasing pore-size diameter, suggesting that the macropore and mesopore types present more complex pore-throat structures than the transitional type. The total fractal dimension (Dtotal) indicates that the pore throat structures are complex and heterogeneous. The sealing heights of the gas column have a positive correlation with cement content in calcarenite and a negative correlation with microfracture density. Mesopore-II and transitional pore types make a significant contribution to enhancing the breakthrough pressure. The fractal variations mainly result from macropores and mesopores, while transitional pores and micropores weaken the impact of the whole pore system on the Dtotal value. The heterogeneity and anisotropy of macropores is the main control on the sealing capacity of the cap rock. The increasing of D1 considerably contributes to the pore shape heterogeneity and enhances the capillary resistance force to hydrocarbon migration. Therefore, the fractal dimension is an effective approach for investigating the pore throat structure and sealing capacity of carbonate cap rocks.
Original languageEnglish
Pages (from-to)557-579
Number of pages3
JournalMarine and Petroleum Geology
Volume102
Early online date15 Jan 2019
DOIs
Publication statusPublished - Apr 2019

Fingerprint

cap rock
sealing
caps
carbonate rock
Ordovician
China
fractals
carbonates
macropore
rocks
porosity
basin
throats
calcarenite
hydrocarbon migration
micrite
capillary pressure
basin evolution
petrography
gas

Keywords

  • Carbonate cap rock
  • Pore structure
  • Fractal characteristics
  • Sealing capacity

ASJC Scopus subject areas

  • Economic Geology
  • Geology
  • Geophysics
  • Oceanography
  • Stratigraphy

Cite this

Impact of pore structure and fractal characteristics on the sealing capacity of Ordovician carbonate cap rock in the Tarim Basin, China. / Wu, Jun; Fan, Tailiang (Corresponding Author); Gomez Rivas, Enrique; Gao, Zhiqian; Yao, Shuqing; Li, Wenhuan; Zhang, Chenjia; Sun, Qingqing; Gu, Yu; Xiang, Man.

In: Marine and Petroleum Geology, Vol. 102, 04.2019, p. 557-579.

Research output: Contribution to journalArticle

Wu, Jun ; Fan, Tailiang ; Gomez Rivas, Enrique ; Gao, Zhiqian ; Yao, Shuqing ; Li, Wenhuan ; Zhang, Chenjia ; Sun, Qingqing ; Gu, Yu ; Xiang, Man. / Impact of pore structure and fractal characteristics on the sealing capacity of Ordovician carbonate cap rock in the Tarim Basin, China. In: Marine and Petroleum Geology. 2019 ; Vol. 102. pp. 557-579.
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abstract = "Evaluating the heterogeneity and sealing capacity of carbonate cap rocks is of great significance for hydrocarbon production. However, the main controls on pore size distribution in carbonate cap rocks are not well constrained. In this contribution we analyze drill core samples of carbonate cap rocks from the Ordovician Yingshan Formation (Tarim Basin) to study their pore properties and investigate the controls of pore-throat structure and fractal dimension on the sealing capacity of the cap rock. Results from petrography and a combination of mercury injection capillary pressure and nitrogen gas adsorption tests reveal that there are four lithological cap rock types, with micrite being the most prevalent one, followed by calcarenite. Six types of pore-throat structures and fractal dimensions (from D1 to D6) are classified based on the pore size distributions, including macropore-I, macropore-II, mesopore-I, mesopore-II, transitional pore-I and transitional pore-II. The fractal dimensions show that there is a decreasing trend from D1 to D6 with decreasing pore-size diameter, suggesting that the macropore and mesopore types present more complex pore-throat structures than the transitional type. The total fractal dimension (Dtotal) indicates that the pore throat structures are complex and heterogeneous. The sealing heights of the gas column have a positive correlation with cement content in calcarenite and a negative correlation with microfracture density. Mesopore-II and transitional pore types make a significant contribution to enhancing the breakthrough pressure. The fractal variations mainly result from macropores and mesopores, while transitional pores and micropores weaken the impact of the whole pore system on the Dtotal value. The heterogeneity and anisotropy of macropores is the main control on the sealing capacity of the cap rock. The increasing of D1 considerably contributes to the pore shape heterogeneity and enhances the capillary resistance force to hydrocarbon migration. Therefore, the fractal dimension is an effective approach for investigating the pore throat structure and sealing capacity of carbonate cap rocks.",
keywords = "Carbonate cap rock, Pore structure, Fractal characteristics, Sealing capacity",
author = "Jun Wu and Tailiang Fan and {Gomez Rivas}, Enrique and Zhiqian Gao and Shuqing Yao and Wenhuan Li and Chenjia Zhang and Qingqing Sun and Yu Gu and Man Xiang",
note = "This study was supported by the Major National Science-Technology Projects of China (Nos. 2017ZX05005-002-003 and 2017ZX05009-002), China Scholarship Council (No. 201806400037), National Natural Science Foundation of China (No. 51574208), Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA14010201-02) and Fundamental Research Funds for the Central Universities (No. 2-9-2015-141). Many thanks to Xinxin Yin and Xue Fan for their help in rock samples preparation. We are grateful to the Editor-in-Chief Qinhong Hu, Associate Editor Hugh Daigle and three anonymous reviewers for their constructive suggestions and critical comments that significantly improved the manuscript.",
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N2 - Evaluating the heterogeneity and sealing capacity of carbonate cap rocks is of great significance for hydrocarbon production. However, the main controls on pore size distribution in carbonate cap rocks are not well constrained. In this contribution we analyze drill core samples of carbonate cap rocks from the Ordovician Yingshan Formation (Tarim Basin) to study their pore properties and investigate the controls of pore-throat structure and fractal dimension on the sealing capacity of the cap rock. Results from petrography and a combination of mercury injection capillary pressure and nitrogen gas adsorption tests reveal that there are four lithological cap rock types, with micrite being the most prevalent one, followed by calcarenite. Six types of pore-throat structures and fractal dimensions (from D1 to D6) are classified based on the pore size distributions, including macropore-I, macropore-II, mesopore-I, mesopore-II, transitional pore-I and transitional pore-II. The fractal dimensions show that there is a decreasing trend from D1 to D6 with decreasing pore-size diameter, suggesting that the macropore and mesopore types present more complex pore-throat structures than the transitional type. The total fractal dimension (Dtotal) indicates that the pore throat structures are complex and heterogeneous. The sealing heights of the gas column have a positive correlation with cement content in calcarenite and a negative correlation with microfracture density. Mesopore-II and transitional pore types make a significant contribution to enhancing the breakthrough pressure. The fractal variations mainly result from macropores and mesopores, while transitional pores and micropores weaken the impact of the whole pore system on the Dtotal value. The heterogeneity and anisotropy of macropores is the main control on the sealing capacity of the cap rock. The increasing of D1 considerably contributes to the pore shape heterogeneity and enhances the capillary resistance force to hydrocarbon migration. Therefore, the fractal dimension is an effective approach for investigating the pore throat structure and sealing capacity of carbonate cap rocks.

AB - Evaluating the heterogeneity and sealing capacity of carbonate cap rocks is of great significance for hydrocarbon production. However, the main controls on pore size distribution in carbonate cap rocks are not well constrained. In this contribution we analyze drill core samples of carbonate cap rocks from the Ordovician Yingshan Formation (Tarim Basin) to study their pore properties and investigate the controls of pore-throat structure and fractal dimension on the sealing capacity of the cap rock. Results from petrography and a combination of mercury injection capillary pressure and nitrogen gas adsorption tests reveal that there are four lithological cap rock types, with micrite being the most prevalent one, followed by calcarenite. Six types of pore-throat structures and fractal dimensions (from D1 to D6) are classified based on the pore size distributions, including macropore-I, macropore-II, mesopore-I, mesopore-II, transitional pore-I and transitional pore-II. The fractal dimensions show that there is a decreasing trend from D1 to D6 with decreasing pore-size diameter, suggesting that the macropore and mesopore types present more complex pore-throat structures than the transitional type. The total fractal dimension (Dtotal) indicates that the pore throat structures are complex and heterogeneous. The sealing heights of the gas column have a positive correlation with cement content in calcarenite and a negative correlation with microfracture density. Mesopore-II and transitional pore types make a significant contribution to enhancing the breakthrough pressure. The fractal variations mainly result from macropores and mesopores, while transitional pores and micropores weaken the impact of the whole pore system on the Dtotal value. The heterogeneity and anisotropy of macropores is the main control on the sealing capacity of the cap rock. The increasing of D1 considerably contributes to the pore shape heterogeneity and enhances the capillary resistance force to hydrocarbon migration. Therefore, the fractal dimension is an effective approach for investigating the pore throat structure and sealing capacity of carbonate cap rocks.

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