Insights into Heterogeneity and Representative Elementary Volume of Vuggy Dolostones

Yufang Xue, Zhongxian Cai (), Heng Zhang, Qingbing Liu, Lanpu Chen, Jiyuan Gao and Fangjie Hu
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Yufang Xue: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Lumo Road No.388, Wuhan 430074, China
Zhongxian Cai: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Lumo Road No.388, Wuhan 430074, China
Heng Zhang: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Lumo Road No.388, Wuhan 430074, China
Qingbing Liu: School of Earth Resources, China University of Geosciences, Wuhan 430074, China
Lanpu Chen: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Lumo Road No.388, Wuhan 430074, China
Jiyuan Gao: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Lumo Road No.388, Wuhan 430074, China
Fangjie Hu: Research Institute of Exploration and Development, PetroChina Tarim Oilfield Company, Korla 841000, China

Energies, 2022, vol. 15, issue 16, 1-24

Abstract: Carbonate reservoirs commonly have significant heterogeneity and complex pore systems due to the multi-scale characteristic. Therefore, it is quite challenging to predict the petrophysical properties of such reservoirs based on restricted experimental data. In order to study the heterogeneity and size of the representative elementary volume (REV) of vuggy dolostones, a total of 26 samples with pore sizes ranging from micrometers to centimeters were collected from the Cambrian Xiaoerbulake Formation at the Kalping uplift in the Tarim Basin of northwestern China. In terms of the distribution of pore size and contribution of pores to porosity obtained by medical computed tomography testing, four types of pore systems (Types I–IV) were identified. The heterogeneity of carbonate reservoirs was further quantitatively evaluated by calculating the parameters of pore structure, heterogeneity, and porosity cyclicity. The results indicate that different pore systems yield variable porosities, pore structures, and heterogeneity. The porosity is relatively higher in Type-II and Type-IV samples compared to those of Type-I and Type-III. It is caused by well-developed large vugs in the former two types of samples, which increase porosity and reduce heterogeneity. Furthermore, the REV was calculated by deriving the coefficient of variation. Nine of the twenty-six samples reach the REV within the volume of traditional core plugs, which indicates that the REV sizes of vuggy dolostones are commonly much larger than the volume of traditional core plugs. Finally, this study indicates that REV sizes are affected by diverse factors. It can be effectively predicted by a new model established based on the relationship between REV sizes and quantitative parameters. The correlated coefficient of this model reaches 0.9320. The results of this study give more insights into accurately evaluating the petrophysical properties of vuggy carbonate reservoirs.

Keywords: medical-CT; vuggy carbonate; representative elementary volume; quantitative characterization of heterogeneity; Xiaoerbulake Formation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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