High Pressure Mercury Intrusion Porosimetry Analysis of the Influence of Fractal Dimensions on the Permeability of Tight Sandstone Oil Reservoirs

This paper investigated fractal characteristics of microscale and nanoscale pore structures in carbonates using High-Pressure Mercury Intrusion (HPMI). Firstly, four different fractal models, i.e., 2D capillary tube model, 3D capillary tube model, geometry model, and thermodynamic model, were used to calculate fractal dimensions of carbonate core samples from HPMI curves. Afterwards, the relationships between the calculated fractal dimensions and carbonate petrophysical properties were analysed. Finally, fractal permeability model was used to predict carbonate permeability and then compared with Winland permeability model. The research results demonstrate that the calculated fractal dimensions strongly depend on the fractal models used. Compared with the other three fractal models, 3D capillary tube model can effectively reflect the fractal characteristics of carbonate microscale and nanoscale pores. Fractal dimensions of microscale pores positively correlate with fractal dimensions of the entire carbonate pores, yet negatively correlate with fractal dimensions of nanoscale pores. Although nanoscale pores widely develop in carbonates, microscale pores have greater impact on the fractal characteristics of the entire pores. Fractal permeability model is applicable in predicting carbonate permeability, and compared with the Winland permeability model, its calculation errors are acceptable.

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The validity of high pressure mercury intrusion porosimetry

Journal of Colloid and Interface Science ◽

10.1016/0021-9797(78)90212-6 ◽

1978 ◽

Vol 67 (1) ◽

pp. 42-47 ◽

Cited By ~ 36

Author(s):

Douglas N Winslow

Keyword(s):

High Pressure ◽

Mercury Intrusion Porosimetry ◽

Mercury Intrusion

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FRACTAL CHARACTERIZATION OF TIGHT OIL RESERVOIR PORE STRUCTURE USING NUCLEAR MAGNETIC RESONANCE AND MERCURY INTRUSION POROSIMETRY

Fractals ◽

10.1142/s0218348x18400170 ◽

2018 ◽

Vol 26 (02) ◽

pp. 1840017 ◽

Cited By ~ 28

Author(s):

FUYONG WANG ◽

KUN YANG ◽

JIANCHAO CAI

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Pore Structure ◽

Pore Size ◽

Mercury Intrusion Porosimetry ◽

Fractal Dimensions ◽

Structure Characterization ◽

Tight Oil ◽

Petrophysical Properties ◽

Mercury Intrusion

Tight oil sandstones have the characteristics of narrow pore throats, complex pore structures and strong heterogeneities. Using nuclear magnetic resonance (NMR) and mercury intrusion porosimetry (MIP), this paper presents an advanced fractal analysis of the pore structures and petrophysical properties of the tight oil sandstones from Yanchang Formation, Ordos Basin of China. Firstly, nine typical tight oil sandstone core samples were selected to conduct NMR and MIP test for pore structure characterization. Next, with the pore size distribution derived from MIP, it was found that the relationships between NMR transverse relaxation time [Formula: see text] and pore size are more accordant with the power function relations, which were applied to derive pore size distribution from NMR rather than the linear relation. Moreover, fractal dimensions of micropores, mesopores and macropores were calculated from NMR [Formula: see text] spectrum. Finally, the relationships between the fractal dimensions of different size pores calculated from NMR [Formula: see text] spectrum and petrophysical properties of tight oil sandstones were analyzed. These studies demonstrate that the combination of NMR and MIP can improve the accuracy of pore structure characterization and fractal dimensions calculated from NMR [Formula: see text] spectrum are effective for petrophysical properties analysis.

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Full‐Scale Pore Structure and Fractal Dimension of the Longmaxi Shale from the Southern Sichuan Basin: Investigations Using FE‐SEM, Gas Adsorption and Mercury Intrusion Porosimetry

Minerals ◽

10.3390/min9090543 ◽

2019 ◽

Vol 9 (9) ◽

pp. 543 ◽

Cited By ~ 10

Author(s):

Wang ◽

Jiang ◽

Chang ◽

Zhu ◽

...

Keyword(s):

Organic Matter ◽

Fractal Dimension ◽

Pore Structure ◽

Clay Minerals ◽

Sichuan Basin ◽

Mercury Intrusion Porosimetry ◽

Fractal Dimensions ◽

Full Scale ◽

Mercury Intrusion ◽

Longmaxi Shale

Pore structure determines the gas occurrence and storage properties of gas shale and is a vital element for reservoir evaluation and shale gas resources assessment. Field emission scanning electron microscopy (FE‐SEM), high‐pressure mercury intrusion porosimetry (HMIP), and low‐pressure N2/CO2 adsorption were used to qualitatively and quantitatively characterize full‐scale pore structure of Longmaxi (LM) shale from the southern Sichuan Basin. Fractal dimension and its controlling factors were also discussed in our study. Longmaxi shale mainly developed organic matter (OM) pores, interparticle pores, intraparticle pores, and microfracture, of which the OM pores dominated the pore system. The pore diameters are mainly distributed in the ranges of 0.4–0.7 nm, 2–20 nm and 40–200 μm. Micro‐, meso‐ and macropores contribute 24%, 57% and 19% of the total pore volume (PV), respectively, and 64.5%, 34.6%, and 0.9% of the total specific surface area (SSA). Organic matter and clay minerals have a positive contribution to pore development. While high brittle mineral content can inhibit shale pore development. The fractal dimensions D1 and D2 which represents the roughness of the shale surface and irregularity of the space structure, respectively, are calculated based on N2 desorption data. The value of D1 is in the range of 2.6480–2.7334 (average of 2.6857), D2 is in the range of 2.8924–2.9439 (average of 2.9229), which indicates that Longmaxi shales have a rather irregular pore morphology as well as complex pore structure. Both PV and SSA positively correlated with fractal dimensions D1 and D2. The fractal dimension D1 decreases with increasing average pore diameter, while D2 is on the contrary. These results suggest that the small pores have a higher roughness surface, while the larger pores have a more complex spatial structure. The fractal dimensions of shale are jointly controlled by OM, clays and brittle minerals. The TOC content is the key factor which has a positive correlation with the fractal dimension. Clay minerals have a negative influence on fractal dimension D1, and positive influence D2, while brittle minerals show an opposite effect compared with clay minerals.

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Fractal analysis of bentonite modified with heteropoly acid using nitrogen sorption and mercury intrusion porosimetry

Journal of the Serbian Chemical Society ◽

10.2298/jsc101027126p ◽

2011 ◽

Vol 76 (10) ◽

pp. 1403-1410 ◽

Cited By ~ 2

Author(s):

Srdjan Petrovic ◽

Zorica Vukovic ◽

Tatjana Novakovic ◽

Zoran Nedic ◽

Ljiljana Rozic

Keyword(s):

Fractal Dimension ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Heteropoly Acid ◽

Mercury Intrusion Porosimetry ◽

Fractal Dimensions ◽

Surface Fractal Dimension ◽

Mercury Intrusion ◽

Surface Fractal

Experimental adsorption isotherms were used to evaluate the specific surface area and the surface fractal dimensions of acid-activated bentonite samples modified with a heteropoly acid (HPW). The aim of the investigations was to search for correlations between the specific surface area and the geometric heterogeneity, as characterized by the surface fractal dimension and the content of added acid. In addition, mercury intrusion was employed to evaluate the porous microstructures of these materials. The results from the Frankel-Halsey-Hill method showed that, in the p/p0 region from 0.75 to 0.96, surface fractal dimension increased with increasing content of heteropoly acid. The results from mercury intrusion porosimetry (MIP) data showed the generation of mesoporous structures with important topographical modifications, indicating an increase in the roughness (fractal geometry) of the surface of the solids as a consequence of the modification with the heteropoly acid. By comparison, MIP is preferable for the characterization because of its wide effective probing range.

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Effect of Shale Sample Particle Size on Pore Structure Obtained from High Pressure Mercury Intrusion Porosimetry

Geofluids ◽

10.1155/2021/5581541 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Zhiye Gao ◽

Longfei Duan ◽

Qinhong Hu ◽

Shuling Xiong ◽

Tongwei Zhang

Keyword(s):

Particle Size ◽

High Pressure ◽

Pore Structure ◽

Mercury Intrusion Porosimetry ◽

Rapid Development ◽

Structure Characterization ◽

Barnett Shale ◽

Skeletal Density ◽

Mercury Intrusion ◽

Shale Sample

With the rapid development of unconventional oil and gas, the pore structure characterization of shale reservoirs has attracted an increasing attention. High pressure mercury intrusion porosimetry (HPMIP) has been widely used to quantitatively characterize the pore structure of tight shales. However, the pore structure obtained from HPMIP could be significantly affected by the sample particle size used for the analyses. This study mainly investigates the influence of shale sample particle size on the pore structure obtained from HPMIP, using Mississippian-aged Barnett Shale samples. The results show that the porosity of Barnett Shale samples with different particle sizes obtained from HPMIP has an exponentially increasing relation with the particle size, which is mainly caused by the new pores or fractures created during shale crushing process as well as the increasing exposure of blind or closed pores. The amount and proportion of mercury retention during mercury extrusion process increase with the decrease of shale particle size, which is closely related to the increased ink-bottle effect in shale sample with smaller particle size. In addition, the fractal dimension of Barnett Shale is positively related to the particle size, which indicates that the heterogeneity of pore structure is stronger in shale sample with larger particle size. Furthermore, the skeletal density of shale sample increases with the decrease of particle size, which is possibly caused by the differentiation of mineral composition during shale crushing process.

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Characterization of Pore Throat Size Distribution in Tight Sandstones with Nuclear Magnetic Resonance and High-Pressure Mercury Intrusion

Energies ◽

10.3390/en12081528 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1528 ◽

Cited By ~ 11

Author(s):

Hongjun Xu ◽

Yiren Fan ◽

Falong Hu ◽

Changxi Li ◽

Jun Yu ◽

...

Keyword(s):

Nuclear Magnetic Resonance ◽

High Pressure ◽

Pore Throat ◽

Tight Sandstone ◽

Mercury Intrusion ◽

Linear Conversion ◽

Conversion Method ◽

Conversion Coefficients ◽

Nonlinear Conversion

Characterization of pore throat size distribution (PTSD) in tight sandstones is of substantial significance for tight sandstone reservoirs evaluation. High-pressure mercury intrusion (HPMI) and nuclear magnetic resonance (NMR) are the effective methods for characterizing PTSD of reservoirs. NMR T2 spectra is usually converted to mercury intrusion capillary pressure for PTSD characterization. However, the conversion is challenging in tight sandstones due to tiny pore throat sizes. In this paper, the linear conversion method and the nonlinear conversion method are investigated, and the error minimization method and the least square method are proposed to calculate the conversion coefficients of the linear conversion method and the nonlinear conversion method, respectively. Finally, the advantages and disadvantages of these two different conversion methods are discussed and compared with field case study. The research results show that the average linear conversion coefficients of the 20 tight sandstone core plugs collected from Yanchang Formation, Ordos Basin of China is 0.0133 μm/ms; the average nonlinear conversion coefficient is 0.0093 μm/ms and the average nonlinear conversion exponent is 0.725. Although PTSD converted from NMR spectra by the nonlinear conversion method is wider than that obtained from linear conversion method, the nonlinear conversion method can retain the characteristic of bi-modal distribution in PTSD.

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Insights into Multifractal Characterization of Coals by Mercury Intrusion Porosimetry

Energies ◽

10.3390/en12244743 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4743

Author(s):

Sijian Zheng ◽

Yanbin Yao ◽

Shasha Zhang ◽

Yong Liu ◽

Jinhui Yang

Keyword(s):

Multifractal Analysis ◽

Mercury Intrusion Porosimetry ◽

Practical Method ◽

Unconventional Reservoirs ◽

Tight Sandstone ◽

Mercury Intrusion ◽

The Matrix ◽

High Mercury ◽

Heterogeneity Characteristics

Mercury intrusion porosimetry (MIP) as a practical and effective measurement has been widely used in characterizing the pore size distribution (PSD) for unconventional reservoirs (e.g., coals and shales). However, in the process of MIP experiments, the high mercury intrusion pressure may cause matrix compressibility and result in inaccurate estimations of PSD. To get a deeper understanding of the variability and heterogeneity characteristics of the actual PSD in coals, this study firstly corrected the high mercury intrusion pressure data in combination with low-temperature N2 adsorption (LTNA) data. The results show that the matrix compressibility was obvious under the pressure over 24.75 MPa, and the calculated matrix compressibility coefficients of bituminous and anthracite coals range from 0.82 to 2.47 × 10−10 m2/N. Then, multifractal analysis was introduced to evaluate the heterogeneity characteristics of coals based on the corrected MIP data. The multifractal dimension Dmin is positively correlated with vitrinite content, but negatively correlated with inertinite content and mercury intrusion saturation. The multifractal dimension Dmax shows negative relationships with moisture and ash content, and it also emerges as a “U-shaped” trend with efficiency of mercury withdrawal. It is concluded that multifractal analysis can be served as a practical method not only for evaluating the heterogeneity of coal PSDs, but also for other unconventional reservoirs (e.g., shale and tight sandstone).

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