Effect of mineralogy and organic matter on mechanical properties of shale

Kumar, Vikas; Sondergeld, Carl H.; Rai, Chandra

doi:10.1190/int-2014-0238.1

Cited by 29 publications

(15 citation statements)

References 15 publications

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“…Another is the difficulty in isolating kerogen from the shale rock because the process of extracting kerogen may damage the structure of kerogen, thereby changing its mechanical properties. To overcome this limitation, techniques such as nanoindentation are used to measure the mechanical properties of kerogen in situ. ,− The Young’s modulus of kerogen measured from nanoindentation measurements ranges between 6 and 15 GPa. However, the resolution of the technique is limited to the order of micrometers, and in some cases it may not be able to resolve the elastic properties of kerogen, which is often found in the submicron intergranular spaces in the shale rock.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Effect of Maturity on the Elastic Moduli of Kerogen Using Atomistic Simulations

2020

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The mechanical properties of kerogen, the organic constituent of shale source rocks, change as it becomes progressively buried under sediment over geologic time. While these changes are due to both mechanical and chemical mechanisms, the individual impact of these mechanisms is poorly understood. In this work, we use atomistic models to isolate how the elastic properties of kerogen change with maturity. Our results show that increases in kerogen density upon burial are accommodated by proportional increases in the stacking of polyaromatic islands present in its structure. The increased stacking leads to the formation of π−π stacking bonds, which correlates to the increases in the elastic moduli. These results are useful for several reasons. First, they provide an estimate of Poisson's ratio for kerogen over a range of densities and maturities. Second, the results demonstrate how atomistic modeling can be applied to gain new insight into the relationship between kerogen structure and its mechanical properties. Third, the agreement between the elastic moduli measured via simulation and experiment shows that atomistic methods can be utilized to accurately characterize kerogen, which is important for building accurate rock models for hydraulic fracturing simulation.

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Section: Introductionmentioning

confidence: 99%

Modeling the Effect of Maturity on the Elastic Moduli of Kerogen Using Atomistic Simulations

2020

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“…Under normal stratigraphic conditions, the rock skeleton bore overlying formation pressure. The mechanical properties and ability to resist compaction of the shale do not strongly differ when the mineral composition and OM content are similar. ,, However, cracking and converting OM causes volume expansion and overpressure generation while increasing thermal maturity. , Thermal simulation experiments under formation conditions suggested that the highest volume of gas produced during thermal evolution was 1720 times the volume of oil . When the retention coefficient was 0.9, the maximum pressure coefficient of the Qiongzhusi Formation was 2.45 .…”

Section: Discussionmentioning

confidence: 99%

“…The mechanical properties and ability to resist compaction of the shale do not strongly differ when the mineral composition and OM content are similar. 57 , 58 , 63 However, cracking and converting OM causes volume expansion and overpressure generation while increasing thermal maturity. 64 , 65 Thermal simulation experiments under formation conditions suggested that the highest volume of gas produced during thermal evolution was 1720 times the volume of oil.…”

Section: Discussionmentioning

confidence: 99%

“…The mechanical properties of OM are significantly different from those of other minerals in shale . An increased TOC content results in a decreased Young’s modulus, thereby increasing the ductility of the shale, , which makes the shale and pores more likely to be compacted. Moreover, Ma et al suggested that compared to the non-deformed zone, OM pores in the mesopores and macropores in the deformed zone collapse during tectonic deformation.…”

Section: Discussionmentioning

confidence: 99%

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Impact of Minerals and Sealing Systems on the Pore Characteristics of the Qiongzhusi Formation Shale in the Southern Sichuan Basin

Liu

Zhou

et al. 2022

ACS Omega

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The characteristics, distribution, and preservation of pores are vital in controlling the storage and distribution of shale gas. The Qiongzhusi Formation shales taken from different members with similar tectonic and thermal evolutions were used to evaluate the response of pore characteristics to minerals and sealing systems using field-emission scanning electron microscopy and gas adsorption. Because of differences in mineral structure and arrangement, feldspar, organic matter (OM)–clay, OM–rutile, and OM–apatite aggregates facilitate multiple types of pores in the shale and influence the relative proportions of surface porosity for different types of pores owing to differences in mineral structure and arrangement. Rigid frameworks and pressure shadows formed by rigid minerals and OM–mineral aggregates preserved OM and pores to some extent. The sealing capacity of the floor controls the sealing system and hydrocarbon expulsion efficiency of the Qiongzhusi Formation in different members. During thermal evolution, the amount of hydrocarbons generated and expelled affected the stress equilibrium state between the pore pressure and external stress, influencing the compaction intensity of shales. The OM pore development characteristics were evolved with variation in the stress equilibrium state in different sealing systems. Once the stress equilibrium state was disrupted, the OM pores deformed, narrowed, or even closed under the influence of compaction owing to the loss of overpressure support. The pore characteristics of the Qiongzhusi Formation shales responded significantly to different sealing systems. A few OM pores are flat and slitlike in the open system, whereas numerous OM pores are round and elliptical in the semiopen system. Meanwhile, the average diameter of the OM pores in the open system was reduced by approximately 40.2% compared with that of the semiopen system. Furthermore, the pore volume and specific surface area of the mesopores for open system shales were reduced by 38.4% and 37.7%, respectively, compared to the semiopen system. These findings will improve the understanding of the distribution and preservation of pore in shale and help assess the sweet-spot members for the Qiongzhusi Formation shale gas.

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“…The mechanical behavior of organic matter is particularly difficult to constrain and is the focus of much current research. Due to its relative softness, the mechanical behavior of shale is greatly influenced by even a few percent of this constituent (Kumar et al., 2015; Sayers, 2013; Vernik & Milovac, 2011). Various methods have been used in attempts to constrain its mechanical properties, including nanoindentation (Ahmadov et al., 2009; Zargari et al., 2013; Zeszotarski et al., 2004) and ultrasonic measurements on samples of isolated kerogen (Yan & Han, 2013).…”

Section: Introductionmentioning

confidence: 99%

Effect of Diagenesis on Geomechanical Properties of Organic‐Rich Calcareous Shale: A Multiscale Investigation

et al. 2021

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Effect of mineralogy and organic matter on mechanical properties of shale

Cited by 29 publications

References 15 publications

Modeling the Effect of Maturity on the Elastic Moduli of Kerogen Using Atomistic Simulations

Modeling the Effect of Maturity on the Elastic Moduli of Kerogen Using Atomistic Simulations

Impact of Minerals and Sealing Systems on the Pore Characteristics of the Qiongzhusi Formation Shale in the Southern Sichuan Basin

Effect of Diagenesis on Geomechanical Properties of Organic‐Rich Calcareous Shale: A Multiscale Investigation

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