Estimating irreducible water saturation and permeability of sandstones from nuclear magnetic resonance measurements by fractal analysis

Peng, Ling; Zhang, Chi; Ma, Huolin; Pan, Heping

doi:10.1016/j.marpetgeo.2019.07.037

Cited by 29 publications

(13 citation statements)

References 59 publications

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“…The pore system’s fractal character has been validated by earlier investigations on sedimentary rocks . On the basis of SEM, thin sections, and mercury intrusions, many approaches have been put forward to compute the dimensions of fractals of pore structure. − But in this investigation, only the mercury intrusion method was taken into account. To obtain dimensions of fractals from capillary pressure curves, there have primarily been three methods developed .…”

Section: Experimental Methodsmentioning

confidence: 99%

“…There have been a number of models proposed for calculating the dimensions of fractals using mercury intrusion porosimetry (MIP). , This study used the capillary tube model to calculate the dimensions of fractals. , This simplified mathematical relationship can be expressed as follows: where Df 3 represents the dimensions of fractals of the wetting phase model, r max represents the maximum pore radius, and r min represents the minimum pore radius. Because r max is far larger than r min in the samples, the fractal formula can be obtained assuming that the wetting contact angle is unaffected by the pore-throat size. …”

Section: Experimental Methodsmentioning

confidence: 99%

“…33,34 This study used the capillary tube model to calculate the dimensions of fractals. 35,36 This simplified mathematical relationship can be expressed as follows:…”

Section: Analysis Of X-raymentioning

confidence: 99%

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Study of Fractal and Multifractal Features of Pore Structure in Tight Sandstone Reservoirs of the Permian Lucaogou Formation, Jimsar Sag, Junggar Basin, Northwest China

Han

Guan

Dan³

et al. 2022

ACS Omega

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The primary factor impacting the tight sandstone reservoirs and fluid flow capacity represents the pore-throat structure. On the basis of petrophysical characteristics test, scanning electron microscopy (SEM), and casting thin-section examination of tight sandstone reservoir specimens from the Permian Lucaogou Formation in Jimsar Sag, Junggar Basin., the full-size pore-throat parameters and distribution characteristics were determined by constant-rate mercury injection (CRMI) analysis. Using fractal theory and multifractal theory, the pore architectures of sandstone pores are analyzed. Mercury intrusion capillary pressure (MICP) is used to compute the dimensions of fractals using various fractal models and multifractal characteristics. Analysis is done on the relationships between tight sandstone pore architectures and fractal and multifractal characteristics. According to the research, a network of tightly packed sandstone pores may be assessed using the dimensions of fractals computed from a 3D capillary model. When displacement pressure is increased, the dimensions of fractals rise; when permeability, pore-throat diameter, and variable coefficient are increased, it falls. Tight sandstone pores exhibit multifractal features, according to the multifractal analysis, and multifractal parameters may depict the size, concentration, and asymmetry of the pore size distribution (PSD). Sandstone’s PSD is comparable when its multifractal parameters (Δα, Δ f , α 0 , α 1 , α 2 ) are identical. Pore diameters of tight sandstone are positively connected with information dimensions D 1 and correlation dimensions D 2 , and information dimensions D 1 have a greater impact on PSD than correlation dimensions D 2 . Additionally, the 3D capillary model’s dimensions of fractals and D 1 exhibit a substantial negative association. These findings play a significant guiding role in the quantitative characterization of unconventional reservoir pore structures. The multifractal technique is effective to define the heterogeneity of the sandstone pore system and to differentiate between distinct PSD in heterogeneity.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

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Study of Fractal and Multifractal Features of Pore Structure in Tight Sandstone Reservoirs of the Permian Lucaogou Formation, Jimsar Sag, Junggar Basin, Northwest China

Han

Guan

Dan³

et al. 2022

ACS Omega

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“…Moreover, the rate‐controlled mercury penetration method was used to analyse the pore‐throat radius of different types of tight sandstones and the correlation between the pore‐throat radius and the physical properties of reservoirs, in order to determine the impacts of pore‐throat radius on the reservoir permeability. The NMR is a useful tool for analysing the characteristics of pore fluids in reservoirs, especially for determining the movable and irreducible water saturation (Gong et al, 2019; Peng, Zhang, Ma, & Pan, 2019). The NMR T2 spectrum was analysed to determine the movable fluid saturation of samples with different physical properties in the study area and to further define the pattern of different porosity and permeability varying with the movable fluid saturation.…”

Section: Samples and Methodsmentioning

confidence: 99%

Pore structure and reservoir physical properties for effective development of tight sandstone gas: A case study from the Central Sichuan Basin, China

et al. 2022

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Several large gas fields have been found in the Central Sichuan Basin in recent years, with proven reserves of more than 100 × 10 9 m3. Among these, the tight sandstone gas in the Late Triassic Xujiahe Formation is a key target in the Sichuan Basin. The key to the discovery of high‐yield areas rich in tight sandstone gas is to determine the pore structures and the lower limits of effective physical properties of reservoirs that control natural gas accumulation. In this study, we investigate the Late Triassic second Member of the Xujiahe Formation (hereinafter referred to as the Xu2 Member) in the Central Sichuan Basin as an example. We analyse the distribution characteristics of pores and throats in the reservoirs and identify that the reservoir in the study area is mainly characterized by small pores and narrow throats. The physical properties of reservoirs in the area are mainly controlled by pore‐throat radius and the permeability–porosity ratio. Nuclear magnetic resonance analysis indicates that the irreducible water saturation is mostly more than 50% and is inversely correlated with the physical properties of reservoirs in the study area. Meanwhile, with an increase in the physical properties of reservoirs, the proportion of large pores increases and the irreducible water saturation rapidly decreases. According to the gas–water two‐phase seepage experiment, for reservoirs with good physical properties, the gas relative permeability significantly increases with an increase in gas saturation and the reservoir permeability has more significant effects. Where the reservoir permeability is less than 0.4 mD, the permeability of both gas phase and water phases is only less than 0.1, and the mobility of both gas and water is poor. Only when the reservoir permeability is more than 0.4 mD, can the gas relative permeability reach more than 0.3, and the water mobility is significantly inhibited. In this case, favourable results can be achieved from the natural gas development. As verified by the development of the tight sandstone reservoirs in the Xu2 Member in Central Sichuan Basin, the lower limits of physical properties allowing for effective natural gas development include the reservoir permeability of more than 0.1 mD (preferably more than 0.2 mD) and the reservoir porosity of greater than 6%–7%.

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“…Several models for estimating permeability have been developed (Peng et al 2019;Solatpour and Kantzas 2019). However, these correlations assumed the same surface relaxivity for the rock samples, thus, there is need to correct for the variations of surface relaxivity across samples.…”

Section: Permeabilitymentioning

confidence: 99%

A review on the applications of nuclear magnetic resonance (NMR) in the oil and gas industry: laboratory and field-scale measurements

Elsayed

Isah

Hiba

et al. 2022

J Petrol Explor Prod Technol

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This review presents the latest update, applications, techniques of the NMR tools in both laboratory and field scales in the oil and gas upstream industry. The applications of NMR in the laboratory scale were thoroughly reviewed and summarized such as porosity, pores size distribution, permeability, saturations, capillary pressure, and wettability. NMR is an emerging tool to evaluate the improved oil recovery techniques, and it was found to be better than the current techniques used for screening, evaluation, and assessment. For example, NMR can define the recovery of oil/gas from the different pore systems in the rocks compared to other macroscopic techniques that only assess the bulk recovery. This manuscript included different applications for the NMR in enhanced oil recovery research. Also, NMR can be used to evaluate the damage potential of drilling, completion, and production fluids laboratory and field scales. Currently, NMR is used to evaluate the emulsion droplet size and its behavior in the pore space in different applications such as enhanced oil recovery, drilling, completion, etc. NMR tools in the laboratory and field scales can be used to assess the unconventional gas resources and NMR showed a very good potential for exploration and production advancement in unconventional gas fields compared to other tools. Field applications of NMR during exploration and drilling such as logging while drilling, geosteering, etc., were reviewed as well. Finally, the future and potential research directions of NMR tools were introduced which include the application of multi-dimensional NMR and the enhancement of the signal-to-noise ratio of the collected data during the logging while drilling operations.

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Estimating irreducible water saturation and permeability of sandstones from nuclear magnetic resonance measurements by fractal analysis

Cited by 29 publications

References 59 publications

Study of Fractal and Multifractal Features of Pore Structure in Tight Sandstone Reservoirs of the Permian Lucaogou Formation, Jimsar Sag, Junggar Basin, Northwest China

Study of Fractal and Multifractal Features of Pore Structure in Tight Sandstone Reservoirs of the Permian Lucaogou Formation, Jimsar Sag, Junggar Basin, Northwest China

Pore structure and reservoir physical properties for effective development of tight sandstone gas: A case study from the Central Sichuan Basin, China

A review on the applications of nuclear magnetic resonance (NMR) in the oil and gas industry: laboratory and field-scale measurements

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