Quantitative modeling of organic matter connectivity in source rocks using fractal geostatistical analysis

Kuo, Lung-Chuan; Hardy, H. H.; Owili-Eger, Angelus S.C.

doi:10.1016/0146-6380(94)00111-d

Cited by 9 publications

(8 citation statements)

References 26 publications

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“…To date, fractal aggregates and surfaces have been detected in a wide variety of materials such as charcoal, soils, aerosols, aquatic colloids, marine snow, and humic acids ( − ). Although natural fractal aggregates are ubiquitous in the environment, few practical studies on their implications in environmental physicochemical processes have been performed ( , ).…”

Section: Introductionmentioning

confidence: 99%

Langmuir-Derived Model for Diffusion- and Reaction-Limited Adsorption of Organic Compounds on Fractal Aggregates

Dachs

Bayona

1997

Environ. Sci. Technol.

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Natural colloids, aerosols, and aggregates generated in wastewater treatments have fractal geometries, and so not all the surface sites of these aggregates possess the same collision probability. It is this property that modifies the classical Langmuir adsorption isotherm, since it describes the equilibrium of the rate of collisions that adhere with the rate of desorption. In this paper, the growth site probability distribution is computed for aggregates with different fractal dimensions in the two- and three-dimensional models. These distributions are then used to find the adsorption isotherms depending on a model parameter η. This parameter is related to the reactivity of the adsorbate, and its relationship to solubility and molecular size has tentatively been proposed and studied. The low concentration range of the adsorption isotherms can be fitted with the Freundlich isotherm for description purposes. When there is low affinity between adsorbate and matrix (reaction-limited adsorption), linear adsorption isotherms are obtained; conversely, isotherms are less linear when adsorbate reactivity increases. Furthermore, the increase of adsorbate solubility led to lower partition coefficients, in agreement with the results reported in the literature. Therefore, the isotherms obtained with the Langmuir-derived equation take into account the fractal geometry of aggregates and provide a good description of the linear and nonlinear isotherms of organic compounds in terms of their solubility, reactivity, and molecular size.

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Section: Introductionmentioning

confidence: 99%

Langmuir-Derived Model for Diffusion- and Reaction-Limited Adsorption of Organic Compounds on Fractal Aggregates

Dachs

Bayona

1997

Environ. Sci. Technol.

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“…This can provide a viable transport pathway for gas within the mudstone if the organic phase in connected on a larger scale. Kuo et al () suggested that uniformly distributed OM networks lose 3‐D connectivity when the TOC contents fall below 6 wt %. These Posidonia mudstones generally contain >6 wt % TOC (Table ) and so may have a well‐connected organic network.…”

Section: Discussionmentioning

confidence: 99%

Influence of Clay, Calcareous Microfossils, and Organic Matter on the Nature and Diagenetic Evolution of Pore Systems in Mudstones

et al. 2019

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Mudstones exert a fundamental control on the flow of both aqueous and nonaqueous fluids in sedimentary basins. Predicting their flow and storage properties requires an understanding of pore size and connectivity, yet there are very few quantitative descriptions of pore systems of mineralogically and texturally well-characterized mudstones. We use a combination of electron microscopy, mercury injection capillary pressure porosimetry, and CO 2 sorption methods to generate a quantitative description of the size distribution, connectivity, and evolution of pore systems in a sequence of Posidonia Shale mudstones buried to 100-180°C. We place the pore data into a detailed mineralogical, petrographical, and textural context to show that the nature and evolution of porosity and pore systems can be described in terms of associations with clay-rich, microfossil-rich, and organic matter-rich domains, common to many mudstones. Pore size distributions are described by power laws, and pore systems are well connected across the full nanometermicrometer spectrum of pore sizes. However, connected networks occur primarily through pores <10 nm radius, with typically 20-40% of total porosity associated with pores with radii <~3 nm, within both organic matter and the clay matrix. Clay-rich, microfossil-rich, and organic matter-rich domains have distinct pore size distributions which evolve in very different ways with increasing thermal maturity. We suggest that the flow of aqueous and nonaqueous fluids depends not only on the overall connectivity of pores but also the larger-scale connectivity and wetting state of clay-rich, microfossil-rich, and organic matter-rich domains.Plain Language Summary Mudstones are Cinderella sediments: important but neglected. The most abundant sediment type, they act as unconventional oil and gas reservoirs, as top seals to conventional hydrocarbon reservoirs, and as critical barriers to the leakage of CO 2 and radionuclides from underground storage sites. Risking and predicting flow and leakage through these rocks requires a quantitative description of pore systems and their connectivity. This is challenging since even the biggest pores in shales are smaller than a micron, with many pores only a few nanometers in size. Our work uses a combination of techniques to characterize and quantify the nanoporous nature of shales. Pores are generally smaller than 100 nm but are well connected, but mainly through throats less than 20 nm. We have also placed the pore system data into a geological framework in order to be more predictive about the pore systems of shales generally. By quantifying the nature of pores in the various mineral and organic building blocks of shales we can consider the larger scale flow properties of shales and thus their potential either to transmit fluid (useful for a shale gas reservoir) or to retain fluid (useful for a CO 2 or nuclear waste storage site).Quantitative descriptions of pore systems underpin our understanding of the storage and flow of both aqueous and nonaqueous fluids in...

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“…Modeling of organic matter connectivity in source rock suggests that when kerogen is in excess of 7 wt%, it may form a 3D network, which could be subject to compaction (Kuo et al, 1995). It has also been reported that mineralogy of the source rocks may play an important role in organic porosity preservation (Fishman et al, 2012).…”

Section: Organic Porosity Calculationmentioning

confidence: 99%

A dual-porosity model for evaluating petroleum resource potential in unconventional tight-shale plays with application to Utica Shale, Quebec (Canada)

Chen

Lavoie

Malo

et al. 2017

Marine and Petroleum Geology

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Unconventional tight to shale reservoirs vary from tight sandstone/siltstone to organic-rich mudstone/shale, commonly with mixed lithologies. In such reservoir systems, matrix pores and organic pores with different origins and distinct physical and chemical properties co-exist for hydrocarbon storage. Traditional resource assessment methods, designed for conventional reservoirs, cannot handle the two pore systems properly. This study proposes a dual-porosity model to respond to the need for a new method in assessing hydrocarbon resource potential in such reservoir systems. The dual-porosity model treats the two types of pores separately and derives the resource estimates from different sources of data, thus better characterizing unconventional reservoirs with complicated pore systems. The new method also has the flexibility of assessing resource potential for the entire spectrum of mixed lithologies ranging from a complete tight to a pure source rock (organic-rich shale/mudstone) reservoir. The proposed method is illustrated through the assessment of the in-place petroleum resource potential in the Upper Ordovician Utica Shale of southern Quebec, Canada. The results of the application suggest that the proposed approach effectively handles the two pore systems in tight-shale reservoirs effectively and provides a useful tool for estimating resource potential in unconventional plays.

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Quantitative modeling of organic matter connectivity in source rocks using fractal geostatistical analysis

Cited by 9 publications

References 26 publications

Langmuir-Derived Model for Diffusion- and Reaction-Limited Adsorption of Organic Compounds on Fractal Aggregates

Langmuir-Derived Model for Diffusion- and Reaction-Limited Adsorption of Organic Compounds on Fractal Aggregates

Influence of Clay, Calcareous Microfossils, and Organic Matter on the Nature and Diagenetic Evolution of Pore Systems in Mudstones

A dual-porosity model for evaluating petroleum resource potential in unconventional tight-shale plays with application to Utica Shale, Quebec (Canada)

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