Fractal study on pore structure of tight sandstone based on full-scale map

Zhao, Xiaowei; Yang, Zheng; Lin, Wei; Xiong, Shengwu; Luo, Yousong; Liu, X.; Xia, Debin

doi:10.1504/ijogct.2019.102788

Cited by 22 publications

(16 citation statements)

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“…The pore sizes obtained by different methods are different. It is impossible to fully characterize the pore structure of tight reservoirs just by one single method 11‐19 …”

Section: Introductionmentioning

confidence: 99%

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Fang

et al. 2020

Energy Science & Engineering

106

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The full pore size distribution represents the integrated characteristics of micro‐nano pore‐throat systems in tight reservoirs. And it involves experiments of different scales to fully analyze the microscope properties. In this paper, we established a new approach for full pore size characterization through conducting the high‐pressure mercury intrusion (HPMI) experiments and low‐temperature nitrogen gas adsorption (LTN2GA) experiments. Meanwhile, we studied the petrology feature of the tight sandstones through X‐ray diffraction (X‐rD) and TESCAN Integrated Mineral Analyzer (TIMA). Then, we investigated the HPMI capillary pressure curves and pore size distribution characteristics, as well as the adsorption‐desorption isotherms features and BET‐specific surface area. Finally, the BJH, non‐local density functional theory (NLDFT) and the quenched solid density functional theory (QSDFT) are contrasted for analyzing the adsorption and pore size distribution characteristics. The HPMI method characterizes the macropores distribution accurately, and the micro/mesopores take up of 14.47% of the total pore spaces. The physisorption isotherms take on the combining shape of type II and IV(a), and the hysteresis loops are like type H3 combined with H4. The BET‐specific surface area is inversely proportional to permeability, and the constant of adsorption heat shows consistence with the analysis results of mineral content. QSDFT can characterize the pore size distribution of micro/mesopores more accurately than the BJH, HPMI, and NLDFT method. By combining the pores narrower than 34 nm calculated from QSDFT method and pores larger than 34 nm calculated from HPMI data with mercury intrusion pressure lower than 42.65 MPa, the full pore size distribution features of tight sandstones are accurately characterized. The micro/mesopores from the new combination method are 3.72% more than that calculated from the HPMI data, and it is of great significance for the accurate pore distribution evaluation and development of tight reservoirs.

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“…The pore sizes obtained by different methods are different. It is impossible to fully characterize the pore structure of tight reservoirs just by one single method 11‐19 …”

Section: Introductionmentioning

confidence: 99%

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Fang

et al. 2020

Energy Science & Engineering

106

View full text Add to dashboard Cite

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“…where [6]. It can be found that the comprehensive fractal dimension of the tight sandstones in E Basin and Y Basin is basically same.…”

Section: Comprehensive Fractal Dimension and Its Applicationmentioning

confidence: 85%

“…Zhao et al proposed to characterize the fractal features of tight sandstones using comprehensive fractal dimensions. Its calculation formula is as follows [6]:…”

Section: Comprehensive Fractal Dimension and Its Applicationmentioning

confidence: 99%

“…Generally, the development of tight oil requires volumetric fracturing to obtain an industrial oil stream [5]. In addition, the pore throat structure is a significant parameter affecting the seepage of tight oil during the development [6][7][8][9]. However, characterizing the multiscale (nano-millimeter) pore throat structure distribution system of tight sandstones is a difficult research point.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of pore throat characteristics of tight sandstone reservoirs

et al. 2020

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The characterization of pore throat structure in tight reservoirs is the basis for the effective development of tight oil. In order to effectively characterize the pore -throat structure of tight sandstone in E Basin, China, this study used high-pressure mercury intrusion (HPMI) testing technology and thin section (TS) technology to jointly explore the characteristics of tight oil pore throat structure. The results of the TS test show that there are many types of pores in the tight sandstone, mainly the primary intergranular pores, dissolved pores, and microfractures. Based on the pore throat parameters obtained by HPMI experiments, the pore throat radius of tight sandstone is between 0.0035 and 2.6158 µm. There are two peaks in the pore throat distribution curve, indicating that the tight sandstone contains at least two types of pores. This is consistent with the results of the TS experiments. In addition, based on the fractal theory and obtained capillary pressure curve by HPMI experiments, the fractal characteristics of tight sandstone pore throat are quantitatively characterized. The results show that the tight sandstones in E Basin have piecewise fractal (multifractal) features. The segmentation fractal feature occurs at a pore throat radius of approximately 0.06 µm. Therefore, according to the fractal characteristics, the tight sandstone pore throat of the study block is divided into macropores (pore throat radius > 0.06 µm) and micropores (pore throat radius < 0.06 µm). The fractal dimension DL of the macropores is larger than the fractal dimension DS of the micropores, indicating that the surface of the macropores is rough and the pores are irregular. This study cannot only provide certain support for characterizing the size of tight oil pore throat, but also plays an inspiring role in understanding the tight pore structure of tight sandstone.

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“…It is generally believed that the fractal dimension of SQRT (K/Φ) in three-dimensional Euclidean space is mostly in the range of 2-3 [18,19]. e closer the fractal dimension is to 2, the weaker the heterogeneity is and the better the reservoir capability is.…”

mentioning

confidence: 99%

Prediction of Intraformational Remaining Oil Distribution Based on Reservoir Heterogeneity: Application to the J‐Field

Zhang

Fang

Wang

et al. 2021

Advances in Civil Engineering

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At high water cut stage, the study of remaining oil distribution in water-flooding reservoir is the basis of implementing potential-tapping measures and enhancing oil recovery. At present, most of the oilfields in China have entered the stage of ultrahigh water cut. The reserves of the oilfields are highly developed, the situation of water flooding is extremely complex, and it is difficult to predict the distribution of the remaining oil, which seriously restricts the adjustment of the production measures, tapping the potential and improving the ultimate recovery rate. In view of aforementioned difficulties, this study puts forward a research approach to predict remaining oil distribution based on reservoir heterogeneity, which can quantitatively characterize reservoir heterogeneity. In order to avoid the drawback that a single parameter cannot fully describe the characteristics of pore structure, the composite index of pore structure (SQRT(K/Φ)) is introduced to study the pore microstructure. The composite index of pore structure is used to predict the distribution of remaining oil in the formation, and the results are basically consistent with those calculated by numerical simulation. It is concluded that the larger the fractal dimension of the composite index of pore structure is, the stronger the heterogeneity of reservoir is; the smaller the composite index of pore structure is, the smaller the recovery degree is. The composite index of pore structure is used to analyze and predict the distribution of remaining oil in the layer, which provides a new direction for the prediction method of remaining oil.

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Fractal study on pore structure of tight sandstone based on full-scale map

Cited by 22 publications

References 0 publications

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Analysis of pore throat characteristics of tight sandstone reservoirs

Prediction of Intraformational Remaining Oil Distribution Based on Reservoir Heterogeneity: Application to the J‐Field

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