scholarly journals Use of Gas Adsorption and Inversion Methods for Shale Pore Structure Characterization

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2880
Author(s):  
Bryan X. Medina-Rodriguez ◽  
Vladimir Alvarado

The analysis of porosity and pore structure of shale rocks has received special attention in the last decades as unconventional reservoir hydrocarbons have become a larger parcel of the oil and gas market. A variety of techniques are available to provide a satisfactory description of these porous media. Some techniques are based on saturating the porous rock with a fluid to probe the pore structure. In this sense, gases have played an important role in porosity and pore structure characterization, particularly for the analysis of pore size and shapes and storage or intake capacity. In this review, we discuss the use of various gases, with emphasis on N2 and CO2, for characterization of shale pore architecture. We describe the state of the art on the related inversion methods for processing the corresponding isotherms and the procedure to obtain surface area and pore-size distribution. The state of the art is based on the collation of publications in the last 10 years. Limitations of the gas adsorption technique and the associated inversion methods as well as the most suitable scenario for its application are presented in this review. Finally, we discuss the future of gas adsorption for shale characterization, which we believe will rely on hybridization with other techniques to overcome some of the limitations.

This paper provides a general note on the state of the art in the application of nondestructive testing techniques (NDT) for the detection of defects or deteriorations in metallic and nonmetallic oil and gas pipes. The advantages and disadvantages of each technique will be pointed out.


Fractals ◽  
2019 ◽  
Vol 27 (01) ◽  
pp. 1940006 ◽  
Author(s):  
LEI ZHANG ◽  
XUEJUAN ZHANG ◽  
HAO CHAI ◽  
YAOCAI LI ◽  
YONGJIE ZHOU

Fractal dimension is an important parameter in the evaluation of tight reservoirs. For an outcrop section of the Nenjiang formation in the Songliao Basin, China, the pore structure and pore fractal characteristics of shale parasequences were investigated using fractal theory. In addition, factors causing pore structure changes were analyzed using the results of low-temperature nitrogen adsorption and scanning electron microscope (SEM) experiments. Conducive to gas migration and secondary pores development such as dissolution, results showed that nanoscale pores dominated by fracture-like morphology and consequent good internal connectivity were observed in each pore size section within the target layer. Each parasequence is characterized by a sequential upward decrease of average pore size and an upward increase of total pore volume, with an increasing number of pores from 2[Formula: see text]nm to 50[Formula: see text]nm. Pores are isolated from each other, with poor connectivity and relatively complex composition of brittle minerals and clay minerals. Main components of the brittle minerals, quartz and feldspar, occur in 20–50% and higher clay mineral content ranging from 50% to 70%. In the parasequence cycle, clay mineral gradually decreases while the brittle mineral content increases. Fractal dimension is negatively correlated with clay mineral content and positively correlated with brittle mineral (quartz and feldspar) content. The fractal dimension calculated by the imaging method and the FHH method shows an upward increasing tendency in each of the parasequence cycles. This is as a result of different phenomena, varied sediment hydrodynamic forces leading to particle size differences and increased brittle minerals resulting in microcracks, therefore, the fractal dimension of the large pores (imaging method) increases upward in the parasequence. Simultaneously, with increased content and accompanied dissolution of brittle minerals causing an increase of small pores from base to top of the parasequence, the fractal dimension of the small pores (FHH method) grows.


Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2879 ◽  
Author(s):  
Yuming Liu ◽  
Bo Shen ◽  
Zhiqiang Yang ◽  
Peiqiang Zhao

The Bakken Formation is a typical tight oil reservoir and oil production formation in the world. Pore structure is one of the key factors that determine the accumulation and production of the hydrocarbon. In order to study the pore structures and main controlling factors of the Bakken Formation, 12 samples were selected from the Bakken Formation and conducted on a set of experiments including X-ray diffraction mineral analysis (XRD), total organic carbon (TOC), vitrinite reflectance (Ro), and low-temperature nitrogen adsorption experiments. Results showed that the average TOC and Ro of Upper and Lower Bakken shale is 10.72 wt% and 0.86%, respectively. The Bakken Formation develops micropores, mesopores, and macropores. However, the Upper and Lower Bakken shale are dominated by micropores, while the Middle Bakken tight reservoir is dominated by mesopores. The total pore volume and specific surface area of the Middle Bakken are significantly higher than those of the Upper and Lower Bakken, indicating that Middle Bakken is more conducive to the storage of oil and gas. Through analysis, the main controlling factors for the pore structure of the Upper and Lower Bakken shale are TOC and maturity, while those for Middle Bakken are clay and quartz contents.


BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3053-3063
Author(s):  
Liangyan Guo ◽  
Hongchao Cheng ◽  
Junfeng Chen ◽  
Wentao Chen ◽  
Jingyao Zhao

The microscopic pore structure of wood is an important factor that affects its macroscopic properties. In this study, an oak sample was used for pore structure characterization. X-ray computed tomography imaging was carried out, and the scanning results (a multi-layer two-dimensional planar image) were rendered using Avizo software (a three-dimensional stereo image). A digital image processing method was used to identify the characteristics of the three-dimensional pore structure features and to calculate the characteristic parameters, i.e., the porosity (volume/surface), pore area and volume, pore size distribution, and the connectivity. The 27 mm3 oak sample had the following characteristics: a pore size which ranged from 8.56 µm to 1262.84 µm; a pore volume of 1.01 × 1010 µm3; a pore area and volume porosity of 1.12 × 109 µm2 and 37.6%, respectively; a surface porosity range of approximately 36.1% to 39.1%; a pore diameter for axial connection ranging from approximately 164.57 µm to 1262.84 µm; and had corresponding proportions of the pore area and volume of approximately 74.4% and 67.3%, respectively. This information provided useful structural data for the construction of future models.


Fuel ◽  
2015 ◽  
Vol 158 ◽  
pp. 908-917 ◽  
Author(s):  
Baisheng Nie ◽  
Xianfeng Liu ◽  
Longlong Yang ◽  
Junqing Meng ◽  
Xiangchun Li

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Shuwen Zhang ◽  
Xuefu Xian ◽  
Junping Zhou ◽  
Guojun Liu ◽  
Yaowen Guo ◽  
...  

In order to study the effects of particle size on the determination of pore structure in shale, the outcrop of Ordovician Wufeng (WF) and Silurian Longmaxi shale (LMX) samples from Sichuan basin were chosen and crushed into various particle sizes. Then, pore structure was analyzed by using low-pressure gas adsorption (LPGA) tests. The results show that the pore of shales is mainly composed of slit-type pores and open pores. The specific surface areas of shale are mainly contributed by micropores, while the largest proportion of the total pore volume in shale is contributed by mesopores. With the decreasing of particle size, the specific surface area of both samples is decreased, while average pore diameter and the total pore volume are increased gradually. The influences of particle size on the pore structure parameters are more significant for micropore and macropore, as the particle sizes decrease from 2.36 mm to 0.075 mm, the volume of micropores in Longmaxi shale increases from 0.283 cm3/100 g to 0.501 cm3/100 g with an increment almost 40%, while the volume of macropores decreases from 0.732 cm3/100 g to 0.260 cm3/100 g with a decrement about 50%. This study identified the fractal dimensions at relative pressures of 0–0.50 and 0.50–0.995 as D1 and D2, respectively. D1 increases with the decrease of particle size of shale, while D2 shows an opposite tendency in both shale samples.


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