Microscopic pore throat structures and water flooding in heterogeneous low-permeability sandstone reservoirs: A case study of the Jurassic Yan'an Formation in the Huanjiang area, Ordos Basin, Northern China

Zhong, Xinyu; Zhu, Yushuang; Jiao, Tao; Qi, Zhao; Luo, Jun; Xie, Ying; Liu, Linyu

doi:10.1016/j.jseaes.2021.104903

Cited by 23 publications

(27 citation statements)

References 34 publications

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“…This paper focuses on the effect of the throat's size and distribution on CO 2 -oil miscible flooding. The mainstream throat contributes 95% to the permeability of core samples, and its radius can be calculated by the following equation (Meng and Liu, 2019;Wang et al, 2020b;Zhong et al, 2021).…”

Section: Methodology Quantitative Characterization Of Microscopic Por...mentioning

confidence: 99%

Prediction of Minimum Miscibility Pressure for CO2 Flooding Based on Microscopic Pore-Throat Structure

et al. 2022

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CO2 flooding can effectively enhance the recovery of low-permeability reservoirs and realize CO2 geological storage. During the displacement process, the minimum miscible pressure (MMP) of CO2 and oil is an important parameter that affects the displacement effect and storage efficiency. However, the microscopic pore-throat structure of low-permeability reservoirs has significant influences on the fluids and phase behaviors. This paper presented a method to determine the miscible state of CO2 flooding based on the microscopic pore-throat structure. Firstly, a physic model was established to quantitatively characterize the microscopic pore-throat structure. Secondly, taking into consideration the P-R equation of state, the gas-liquid equilibrium in the narrow pore-throat was calculated. On this basis, a MMP prediction model was established correspongdingly by considering the multi-stage contact and mass transfer of CO2-oil. Finally, the results obtained by the proposed model were compared with the experimental results of CO2 flooding, and then the model was applied to the actual reservoir to predict plane distribution of MMP. The curves of MMP distribution and pressure drawdown between wells were combined to determine the position of miscible front and non-miscible area at different production stages. The results have shown that the MMP of core sample calculated by the model was 20.3 MPa, which was comparable to that of CO2 flooding experiment, e.g., 20 MPa, and thus indicatesd a high accuracy of the model. The MMP in the well control area of the Y29-101 well group was 19.8 MPa. During the unsteady flow stage, the miscible-phase front was 430 m from the injection well, while it was 310 m from the injection well during the stable flow stage. This method can accurately determine the specific phase distribution of CO2-oil in the formation, which is of great significance to promote the development of CO2 flooding and storage technology, improve the recovery of low permeability reservoirs, ensure energy supply and reduce carbon emission.

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Section: Methodology Quantitative Characterization Of Microscopic Por...mentioning

confidence: 99%

Prediction of Minimum Miscibility Pressure for CO2 Flooding Based on Microscopic Pore-Throat Structure

et al. 2022

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“…In addition, the sand bodies develop various types of cross-bedding, which are vertically bell-shaped and box-shaped. According to the difference of throats, the pore types of the Yan'an Formation sandstones mainly include four types (Figure 3) (Bhatti et al, 2020;Zhong et al, 2021). The first type has constricted throats with little difference in the size of pores and throats (Figure 3A); the second type has a thin-necked throat, and the size of the throats is significantly lower than the pores (Figure 3B); the third type has deformed sheet-like throats, which are associated with mineral compaction (Figure 3C); the fourth type has tubular throats, which are usually developed in the intercrystalline pores of interstitials, and the pores are mostly filled by kaolinite and illite (Figure 3D).…”

Section: Pore Typesmentioning

confidence: 99%

“…The porosity of the samples is mainly distributed in 9-17%, and the gas permeability is mainly The target sandstone has experienced strong cementation. Cementation refers to the precipitation of supersaturated dissolved components in pore water under the conditions of elevated temperature and pressure, and then the clastic sediments are cemented into rocks (Wang et al, 2017;Zhong et al, 2021). The cementation experienced by the target layer mainly includes clay, siliceous, calcareous and feldspar cementations.…”

Section: Pore Typesmentioning

confidence: 99%

“…FIGURE 1The study area is located in the western margin of the Ordos Basin in the western part of the North China Craton (NCC)(Zhong et al, 2021).Notes: (A) Location of the Ordos Basin; (B) Location of the study area; (C) Lithologic characteristics of the Yan'an Formation coal measures; (D) A stratigraphic profile in the central part of the Ordos Basin.…”

mentioning

confidence: 99%

“…FIGURE 3Major pore types in sandstone reservoirs(Zhong et al, 2021). (A) pore-shrinkage-type throat; (B) neck-shaped throat; (C) sheet-type throat; (D) tubular throat.…”

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confidence: 99%

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Experimental evaluation of microscopic pore structure and fluid migration characteristics of coal-measure sandstone reservoirs

Pan

Peng

2022

Front. Earth Sci.

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Research on the microscopic migration characteristics of fluids in coal measure sandstone has always been a hot spot in the evaluation of reservoir properties. In this study, taking the Yan’an Formation sandstone reservoirs in the Block A of the Ordos Basin as an example, the pore structures and fluid migration characteristics of coal-measure sandstones are systematically studied using a large number of thin sections, SEM (Scanning Electron Microscope), NMR (Nuclear Magnetic Resonance), relative permeability and water-flooding test results. The results show that the Jurassic sandstones in the target layer mainly develop lithic quartz sandstone, and the main pore types are intergranular and dissolution pores, followed by a small amount of intercrystalline pores. The surface porosity of the target sandstones mainly ranges from 7.90 to 10.79%, with an average value of 8.78%. The good correlation between porosity and permeability indicates that the target layer is a pore-type reservoir. The T2 relaxation time of the target layer is mainly distributed within 100 ms. Moreover, the reservoir of the Yan’an Formation has a high saturation of movable fluids, which is mainly distributed in 43.17–71.24%, with an average value of 56.90%. Meanwhile, samples with fractures have higher movable fluid saturations. In addition, the average irreducible water saturation of the Yan’an Formation sandstone reservoir is 35.14%, and the final oil displacement efficiency is 51.14% on average. There is a good positive correlation between the oil displacement efficiency and the co-permeability zone. As the co-permeability zone range increased from 15 to 55%, the oil displacement efficiency increased from 30 to 65%. When the cores develop fractures, they have characteristics of high permeability, high oil recovery rate, high oil displacement efficiency in the anhydrous period, low irreducible water saturation and low residual oil saturation.

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Permeability prediction method of unconsolidated sandstone reservoirs using CT scanning technology and random forest model

Liu,

Feng,

Zhou

et al. 2024

J Petrol Explor Prod Technol

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Developing unconsolidated sandstone reservoirs presents a formidable challenge due to their loose formation, which often triggers alterations in pore parameters and seepage characteristics during water injection processes. This study focuses on a specific reservoir, utilizing micro-CT scanning to examine the intricate relationship between permeability and pore throat structure. Leveraging a random forest model, we establish an empirical formula tailored for high permeability reservoirs. Furthermore, we conduct in-situ CT scanning experiments across various displacement multiples to analyze the pore structure of unconsolidated sandstone cores. The derived relationship curves elucidate the positive correlations between porosity and average pore throat radius with displacement multiples, while revealing a negative correlation with tortuosity. These findings enable the formulation of quantitative formulas for permeability and displacement multiples within the studied block. Such insights prove instrumental in devising effective water injection development strategies, predicting dynamic reserves, and projecting water drive development for analogous unconsolidated sandstone reservoirs undergoing high water cut phases.

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Microscopic pore throat structures and water flooding in heterogeneous low-permeability sandstone reservoirs: A case study of the Jurassic Yan'an Formation in the Huanjiang area, Ordos Basin, Northern China

Cited by 23 publications

References 34 publications

Prediction of Minimum Miscibility Pressure for CO2 Flooding Based on Microscopic Pore-Throat Structure

Prediction of Minimum Miscibility Pressure for CO2 Flooding Based on Microscopic Pore-Throat Structure

Experimental evaluation of microscopic pore structure and fluid migration characteristics of coal-measure sandstone reservoirs

Permeability prediction method of unconsolidated sandstone reservoirs using CT scanning technology and random forest model

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