Nanopore structures of isolated kerogen and bulk shale in Bakken Formation

Liu, Kouqi; Ostadhassan, Mehdi; Zou, Jie; Gentzis, Thomas; Rezaee, Reza; Bubach, Bailey; Carvajal‐Ortiz, Humberto

doi:10.1016/j.fuel.2018.04.034

Cited by 57 publications

(75 citation statements)

References 42 publications

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“…They showed that during step-like pyrolysis, first disconnected pores appear, then the poorly connected pore network transforms into a well-connected one accordingly with maturation and expulsion process, which was proved using TGA [57]. The maturation process also affects the surface roughness of the pores, which is demonstrated by means of multifractal analysis [58].…”

Section: Laboratory Investigationmentioning

confidence: 92%

Cyclic Subcritical Water Injection into Bazhenov Oil Shale: Geochemical and Petrophysical Properties Evolution Due to Hydrothermal Exposure

et al. 2021

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In situ shale or kerogen oil production is a promising approach to developing vast oil shale resources and increasing world energy demand. In this study, cyclic subcritical water injection in oil shale was investigated in laboratory conditions as a method for in situ oil shale retorting. Fifteen non-extracted oil shale samples from Bazhenov Formation in Russia (98 °C and 23.5 MPa reservoir conditions) were hydrothermally treated at 350 °C and in a 25 MPa semi-open system during 50 h in the cyclic regime. The influence of the artificial maturation on geochemical parameters, elastic and microstructural properties was studied. Rock-Eval pyrolysis of non-extracted and extracted oil shale samples before and after hydrothermal exposure and SARA analysis were employed to analyze bitumen and kerogen transformation to mobile hydrocarbons and immobile char. X-ray computed microtomography (XMT) was performed to characterize the microstructural properties of pore space. The results demonstrated significant porosity, specific pore surface area increase, and the appearance of microfractures in organic-rich layers. Acoustic measurements were carried out to estimate the alteration of elastic properties due to hydrothermal treatment. Both Young’s modulus and Poisson’s ratio decreased due to kerogen transformation to heavy oil and bitumen, which remain trapped before further oil and gas generation, and expulsion occurs. Ultimately, a developed kinetic model was applied to match kerogen and bitumen transformation with liquid and gas hydrocarbons production. The nonlinear least-squares optimization problem was solved during the integration of the system of differential equations to match produced hydrocarbons with pyrolysis derived kerogen and bitumen decomposition.

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Section: Laboratory Investigationmentioning

confidence: 92%

Cyclic Subcritical Water Injection into Bazhenov Oil Shale: Geochemical and Petrophysical Properties Evolution Due to Hydrothermal Exposure

et al. 2021

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“…Organic pores in shale reservoirs are mainly developed during the thermal cracking of the hydrocarbon generation phase, and the sizes of organic pores range from 5 nm to 700 nm (as shown in Figure 1). Such organic nanometer pores are well developed in shale reservoirs, providing tremendous surface areas for shale gas adsorption as well as flow paths for gas flow [1,6,7].…”

Section: Gas Flow and Transport Mechanismsmentioning

confidence: 99%

“…The annual production of them has become increasingly important to the global energy supply. As a kind of unconventional natural gas, shale gas is trapped in the source rock with self-accumulation, which is very tight with the permeability range from nD to mD [1][2][3][4][5][6][7]. The shale gas storage in shale reservoirs are mainly with the status of free gas, adsorbed gas, and dissolved gas.…”

Section: Introductionmentioning

confidence: 99%

A Review of Gas Flow and Its Mathematical Models in Shale Gas Reservoirs

et al. 2020

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The application of horizontal wells with multistage hydraulic fracturing technologies has made the development of shale gas reservoirs become a worldwide economical hotspot in recent years. The gas transport mechanisms in shale gas reservoirs are complicated, due to the multiple types of pores with complex pore structure and special process of gas accumulation and transport. Although there have been many attempts to come up with a suitable and practical mathematical model to characterize the shale gas flow process, no unified model has yet been accepted by academia. In this paper, a comprehensive literature review on the mathematical models developed in recent years for describing gas flow in shale gas reservoirs is summarized. Five models incorporating different transport mechanisms are reviewed, including gas viscous flow in natural fractures or macropores, gas ad-desorption on shale organic, gas slippage, diffusion (Knudsen diffusion, Fick diffusion, and surface diffusion), stress dependence, real gas effect, and adsorption layer effect in the nanoshale matrix system, which is quite different from conventional gas reservoir. This review is very helpful to understand the complex gas flow behaviors in shale gas reservoirs and guide the efficient development of shale gas. In addition to the model description, we depicted the type curves of fractured horizontal well with different seepage models. From the review, it can be found that there is some misunderstanding about the essence of Knudsen/Fick diffusion and slippage, which makes different scholars adopt different weighting methods to consider them. Besides, the contribution of each mechanism on the transport mechanisms is still controversial, which needs further in-depth study in the future.

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“…15 Nitrogen adsorption nowadays has become a standard technique for pore structure analysis in shale characterization. [16][17][18][19][20][21] In addition to its applicability for pore size distribution, pore surface area and pore volume determination, researchers have combined fractal dimension analysis with adsorption isotherms to obtain more information from the pores. [22][23][24][25][26] Based on the literature, nearly all the authors utilized the FHH model solely to characterize fractal dimensions of shale rocks without any strong basis.…”

Section: Introductionmentioning

confidence: 99%