Pore Characterization of the Marcellus Shale by Nitrogen Adsorption and Prediction of Its Gas Storage Capacity

In a shale gas reservoir, pore characterization is an important factor to determine gas storage capacity. However, the nanometer (nm) scale pore system in shale is difficult to explore by traditional optical, scanning electron microscopy (SEM) or even nuclear magnetic resonance (NMR) well logging. We investigated the pore structure and storage capacity of the Marcellus Shale through integration of petrophysical analysis from lab and well logging data, and nitrogen adsorption. The isotherm of Marcellus Shale is a composite isotherm, which has features of Type I, Type II and Type IV isotherms with Type H4 of hysteresis loop, suggesting slit-like pores developed in the Marcellus Shale. Quantitative analysis of pore volumes from the nitrogen adsorption indicates that density porosity may be more proper to approximate shale porosity and estimating the shale gas volume. In addition, the specific surface area, micropore and mesopore volumes have positive relationship with kerogen volume and total organic content (TOC). By employing Langmuir and Brunauer-Emmet-Teller (BET) models, simulated result indicates that higher adsorbed quantity of the Marcellus Shale could be the result of increase of micropore volume contributed, by increase of kerogen or TOC content. The proposed equations rapidly compute TOC, a key parameter to predict gas storage capacity in over-matured shale such as the Marcellus Shale.

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Shale Gas-in-Place Calculations Part I: New Pore-Scale Considerations

SPE Journal ◽

10.2118/131772-pa ◽

2011 ◽

Vol 17 (01) ◽

pp. 219-229 ◽

Cited By ~ 289

Author(s):

Ray J. Ambrose ◽

Robert C. Hartman ◽

Mery Diaz-Campos ◽

I. Yucel Akkutlu ◽

Carl H. Sondergeld

Keyword(s):

Shale Gas ◽

Organic Material ◽

Storage Capacity ◽

Pore Space ◽

Ion Beam ◽

Gas Storage ◽

Organic Content ◽

Free Gas ◽

Adsorbed Phase ◽

Small Pore

Summary Using focused-ion-beam (FIB)/scanning-electron-microscope (SEM) imaging technology, a series of 2D and 3D submicroscale investigations revealed a finely dispersed porous organic (kerogen) material embedded within an inorganic matrix. The organic material has pores and capillaries having characteristic lengths typically less than 100 nm. A significant portion of total gas in place appears to be associated with interconnected large nanopores within the organic material. Thermodynamics (phase behavior) of fluids in these pores is quite different; gas residing in a small pore or capillary is rarefied under the influence of organic pore walls and shows a different density profile. This raises serious questions related to gas-in-place calculations: Under reservoir conditions, what fraction of the pore volume of the organic material can be considered available as free gas, and what fraction is taken up by the adsorbed phase? How accurately is the shale-gas storage capacity estimated using the conventional volumetric methods? And finally, do average densities exist for the free and the adsorbed phases? We combine the Langmuir adsorption isotherm with the volumetrics for free gas and formulate a new gas-in-place equation accounting for the pore space taken up by the sorbed phase. The method yields a total-gas-in-place prediction. Molecular dynamics simulations involving methane in small carbon slit-pores of varying size and temperature predict density profiles across the pores and show that (a) the adsorbed methane forms a 0.38-nm monolayer phase and (b) the adsorbed-phase density is 1.8–2.5 times larger than that of bulk methane. These findings could be a more important consideration with larger hydrocarbons and suggest that a significant adjustment is necessary in volume calculations, especially for gas shales high in total organic content. Finally, using typical values for the parameters, calculations show a 10–25% decrease in total gas-storage capacity compared with that using the conventional approach. The role of sorbed gas is more important than previously thought. The new methodology is recommended for estimating shale gas in place.

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Overmature Shale Gas Storage Capacity Evaluation

10.2523/16774-abstract ◽

2013 ◽

Cited By ~ 1

Author(s):

Hua Tian ◽

Shuichang Zhang ◽

Shaobo Liu ◽

Jianping Chen

Keyword(s):

Shale Gas ◽

Storage Capacity ◽

Gas Storage ◽

Capacity Evaluation

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Models of shale gas storage capacity during burial and uplift: Application to Wufeng-Longmaxi shales in the Fuling shale gas field

Marine and Petroleum Geology ◽

10.1016/j.marpetgeo.2019.06.012 ◽

2019 ◽

Vol 109 ◽

pp. 233-244 ◽

Cited By ~ 6

Author(s):

Sile Wei ◽

Sheng He ◽

Zhejun Pan ◽

Xiaowen Guo ◽

Rui Yang ◽

...

Keyword(s):

Shale Gas ◽

Storage Capacity ◽

Gas Storage ◽

Gas Field

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Overmature Shale Gas Storage Capacity Evaluation

10.2523/iptc-16774-abstract ◽

2013 ◽

Cited By ~ 1

Author(s):

Hua Tian ◽

Shuichang Zhang ◽

Shaobo Liu ◽

Jianping Chen

Keyword(s):

Shale Gas ◽

Storage Capacity ◽

Gas Storage ◽

Capacity Evaluation

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Well logging evaluation of the shale gas potential in the lower Silurian Longmaxi Formation, Weiyuan, southern Sichuan Basin, China

Interpretation ◽

10.1190/int-2020-0069.1 ◽

2021 ◽

pp. 1-64

Author(s):

Guangzhao Zhou ◽

Zhiming Hu ◽

Xiangui Liu ◽

Xianggang Duan ◽

Jin Chang

Keyword(s):

Spatial Distribution ◽

Shale Gas ◽

Sichuan Basin ◽

Vitrinite Reflectance ◽

Well Logging ◽

Carbonaceous Shale ◽

Organic Carbon Content ◽

Type I ◽

Longmaxi Formation ◽

Marine Shale

Recent observations of shale gas breakthroughs have in the Weiyuan marine shale gas play in the Sichuan Basin have attracted great interest. To better understand these breakthroughs, we use core description, FIB-SEM data, XRD data, organic geochemistry, and well logging data, to better understand the reservoir characteristics carbonaceous shale, calcareous shale, and siliceous shale lithology, with a focus on the organic-rich shale units. We find conventional well log methods are effective in mapping the spatial distribution of the organic-rich shale in the Weiyuan area where the. total organic carbon content in the Longmaxi Formation ranges from 1.35%-6.95%, averaging 4.42%. The kerogen is Type I-II and the vitrinite reflectance (Ro) is greater than 2.57%, which indicates that the formation is susceptible to shale gas accumulation. The clay mineral content ranges from 48 wt.% to 63 wt.% (avg. 51 wt.%).with illite and chlorite averaging 73.8% and 25.7%, respectively. The brittle mineral quartz and plagioclase content ranges from 32 wt.% to 61 wt.% (avg. 47 wt.%). Compared to the surrounding litholgic units, the marine shale exhibits relatively high GR, CNL, AC, RT, K, and U values and relatively low DEN, PE and Th/U values, allowing us to construct. Cross-plots to define the units of interest. Using the same process, we quantify the TOC content providing a spatial distribution of organic-rich shale using conventional well logging.

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Pore structure and heterogeneity of shale gas reservoirs and its effect on gas storage capacity in the Qiongzhusi Formation

Geoscience Frontiers ◽

10.1016/j.gsf.2021.101244 ◽

2021 ◽

pp. 101244

Author(s):

Shangbin Chen ◽

Zhuo Gong ◽

Xueyuan Li ◽

Huijun Wang ◽

Yang Wang ◽

...

Keyword(s):

Pore Structure ◽

Shale Gas ◽

Storage Capacity ◽

Gas Storage ◽

Gas Reservoirs ◽

Shale Gas Reservoirs

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Compositional characterization and storage capacity of shale samples from La Luna and Conejo Formations (Middle Magdalena basin and the Eastern Cordillera): Implications for evaluation of cretaceous shale gas in Colombia

Boletín de Ciencias de la Tierra ◽

10.15446/rbct.n37.43685 ◽

2015 ◽

pp. 45-53 ◽

Cited By ~ 1

Author(s):

Paula Andrea Pacheco Sintura ◽

Agustín Cardona Molina ◽

Farid B. Cortés

Keyword(s):

Shale Gas ◽

Storage Capacity ◽

Total Porosity ◽

Organic Content ◽

Gas Reservoir ◽

Eastern Cordillera ◽

And Storage ◽

Compositional Characterization ◽

Petroleum Source Rock ◽

La Luna

Shale gas has become a major non-conventional energetical resource. La Luna Formation which is commonly considered as the main petroleum source rock, have also shown to be a major reservoir for shale gas resources. In order to understand the "real" potential of this unit and define exploration strategies, the correlation between compositional and petrophysical patterns. We have analyzed 11 shale samples from La Luna and Conejo Formation in the Middle Magdalena basin and the Eastern Cordillera in order to established its composition, total organic contents, thermal maturity, as well as its total porosity and adsorption capacity. Obtained results suggest that due to its organic content, the presence of quartz and carbonate that these shales have a good quality as a gas reservoir and may have also a moderately good behavior during fracturing.

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Pore structure and sorption capacity investigations of Ediacaran and Lower Silurian gas shales from the Upper Yangtze platform, China

Geomechanics and Geophysics for Geo-Energy and Geo-Resources ◽

10.1007/s40948-021-00262-5 ◽

2021 ◽

Vol 7 (3) ◽

Author(s):

Zhazha Hu ◽

Garri Gaus ◽

Timo Seemann ◽

Qian Zhang ◽

Ralf Littke ◽

...

Keyword(s):

Organic Matter ◽

Pore Structure ◽

Clay Minerals ◽

Sorption Capacity ◽

Shale Gas ◽

Gas Storage ◽

Micropore Volume ◽

Thermal Maturity ◽

Yangtze Platform ◽

Lower Silurian

Abstract The shale gas potential of Ediacaran and Lower Silurian shales from the Upper Yangtze platform is assessed in this study with a focus on the contributions of clay minerals and organic matter to sorption capacity. For this purpose, a multidisciplinary assessment was carried out using petrophysical, mineralogical, petrographic and geochemical methods. In terms of TOC contents (4.2%), brittle mineral contents (68.6%) and maximum gas storage capacities (0.054–0.251 mmol/g) Ediacaran shales from this study show comparable properties to other producing shale gas systems although the thermal maturity is extremely high (VRr = 3.6%). When compared to lower Silurian shales from the same region, it is evident that (1) deeper maximum burial and (2) a lack of silica-associated preservation of the pores resulted in a relatively lower mesopore volume, higher micropore volume fraction and lower overall porosity (Ediacaran shales: 1.4–4.6%; Silurian shales: 6.2–7.4%). Gas production is therefore retarded by poor interconnectivity of the pore system, which was qualitatively demonstrated by comparing experimental gas uptake kinetics. TOC content exhibits a prominent control on sorption capacity and micropore volume for both shales. However, different contributions of clay minerals to sorption capacity were identified. This can partly be attributed to different clay types but is likely also related to burial-induced recrystallisation and different origins of illite. Additionally, it was shown that variations in sorption capacity due to incorrect estimates of clay mineral contribution are in the same range as variations due to differences in thermal maturity. Article highlights Pore structure and gas storage characteristics are evaluated for the first time for Ediacaran Shales from the Upper Yangtze platform Due to a lower free gas storage capacity and diffusivity, the Ediacaran shale can be regarded as a less favorable shale gas prospect when compared to the Silurian shale Clay mineral contribution to sorption capacity is evaluated taking clay mineralogy into consideration Maturity-related changes of organic matter sorption capacity have been discussed on the basis of a compiled data set

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