An improved model for estimating the TOC in shale formations

Zhao, Peiqiang; Ma, Huolin; Rasouli, Vamegh; Liu, Wenhui; Cai, Jianchao; Huang, Zhenhua

doi:10.1016/j.marpetgeo.2017.03.018

Cited by 79 publications

(28 citation statements)

References 20 publications

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“…The unconventional reservoirs such as shale gas and tight oil have been paid more attention since the production of conventional oil and gas decreased [1][2][3]. It is difficult to obtain economic oil flows without horizontal well drilling and fracturing technology, as these unconventional reservoirs are impermeable or extremely low permeable [4,5]. In unconventional reservoirs, the development may be more important than the exploration.…”

Section: Introductionmentioning

confidence: 99%

“…However, the exploration of unconventional resources cannot be neglected. A series of geochemical and petrophysical properties are required to characterize and evaluate [5,6]. Among these parameters, pore structures are important factors affecting the fluid transport both in the hydrocarbon accumulation and production in porous media and are also key parameters for reservoir grading and productivity evaluation [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Liu

Shen

Yang³

et al. 2018

Energies

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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.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Liu

Shen

Yang³

et al. 2018

Energies

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“…It was originally developed using acoustic compressional slowness but also worked with density or compensated neutron measurements. Wang [14] and Zhao [15] improved the TOC estimation accuracy through a revised ∆logR method. The revisions included replacing the level of maturity (LOM) with T max , making the slope and the values of resistivity and porosity of the baseline rock vary with depth, and so on.…”

Section: Methods Explanations Referencesmentioning

confidence: 99%

Improving the Total Organic Carbon Estimation of the Eagle Ford Shale with Density Logs by Considering the Effect of Pyrite

et al. 2018

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Pyrite is a common mineral with a higher density than most other minerals in the Eagle Ford Shale formation. Hence, if pyrite is not considered in the total organic carbon (TOC) estimation, based on density logs, it may lead to errors. In order to improve the accuracy of the TOC estimation, we propose an updated TOC estimation method that incorporates the concentration of pyrite and organic porosity. More than 15 m of Eagle Ford Shale samples were analyzed using Rock-Eval pyrolysis, X-ray fluorescence (XRF), and X-ray diffraction (XRD). TOC, elemental concentration, and mineralogical data were analyzed for a better understanding of the relationship between the concentration of TOC and pyrite content in the Eagle Ford formation. An updated petrophysical model-including parameters such as organic pores, solid organic matter, inorganic pores, pyrite, and inorganic rock matrix without pyrite-was built using the sample data from the Eagle Ford. The model was compared with Schmoker's model and validated with the Eagle Ford field data. The results showed that the updated model had a lower root mean square error (RMSE) than Schmoker's model. Therefore, it could be used in the future estimation of TOC in pyrite-rich formations.

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“…Extensive studies on the methane adsorption capacity and its controlling factors in various shale formations have been conducted, showing that the total organic carbon (TOC) is a main contributor to the adsorbed gas capacity (Ross et al, 2009;Weniger et al, 2010;Gasparik et al, 2012;Zhang et al, 2012;Ji et al, 2015;Wang et al, 2016a;Zhao et al, 2017). In addition, methane in shale formations is typically in the supercritical state as the formation temperature and pressure far exceed its critical properties (-82.5 • C and 4.64 MPa) (Aranovich and Donohue, 270 Zhou, S., et al Advances in Geo-Energy Research 2018, 2(3): 269-281 1996; Do and Do, 2003).…”

Section: Introductionmentioning

confidence: 99%

Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

Zhou

Yang

Wang

et al. 2018

Adv. Geo-Energy Res.

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Abstract:Understanding the methane adsorption mechanism is critical for studying shale gas storage and transport in shale nanopores. In this work, we conducted low-pressure nitrogen adsorption (LPNA), scanning electron microscopy (SEM), and high-pressure methane adsorption experiments on seven shale samples from the Longmaxi formation in Sichuan basin. LPNA and SEM results show that pores in the shale samples are mainly nanometersized and have a broad size distribution. We have also shown that methane should be not only adsorbed in micropores (< 2 nm) but also in mesopores (2-50 nm) by two hypotheses. Therefore, we established a novel DA-LF model by combining the micropore filling and monolayer coverage theories to describe the methane adsorption process in shale. This new model can fit the high-pressure isotherms quite well, and the fitting error of this new model is slightly smaller than the commonly used D-A and L-F models. The absolute adsorption isotherms and the capacities for micropores and mesopores can be calculated using this new model separately, showing that 77% to 97% of methane molecules are adsorbed in micropores. In addition, we conclude that the methane adsorption mechanism in shale is: the majority of methane molecules are filled in micropores, and the remainder are monolayer-adsorbed in mesopores. It is anticipated that our results provide a more accurate explanation of the shale gas adsorption mechanism in shale formations.

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An improved model for estimating the TOC in shale formations

Cited by 79 publications

References 20 publications

Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Pore Structure Characterization and the Controlling Factors of the Bakken Formation

Improving the Total Organic Carbon Estimation of the Eagle Ford Shale with Density Logs by Considering the Effect of Pyrite

Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

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