Abarghani Arash, Gentzis Thomas, Liu Bo, Khatibi Seyedalireza, Bubach Bailey, Ostadhassan Mehdi
Department of Petroleum Engineering, University of North Dakota, Grand Forks, North Dakota 58202, United States.
Core Laboratories, Reservoir Geology Group, 6316 Windfern Road, Houston, Texas 77040, United States.
ACS Omega. 2020 Mar 24;5(13):7135-7148. doi: 10.1021/acsomega.9b03467. eCollection 2020 Apr 7.
Samples were taken at different levels of thermal maturity in the unconventional Bakken source rock. Programmed pyrolysis derived , solid bitumen reflectance, liptinite group maceral UV fluorescence, and nuclear magnetic resonance spectroscopy as different thermal maturity indicators were utilized in order to compare redox-sensitive trace metal (TM) concentration to maturity variations and disclose any probable relationship. Comparing redox-sensitive TMs with total organic carbon revealed the presence of anoxic/euxinic conditions in the depositional environment of the Bakken Shale. Although some of the TMs (V and Mo) exhibit slightly positive correlations with some of the thermal maturity indices used in this study, the correlations between other redox-sensitive TMs with maturity were neutral. Collectively, this study demonstrates that thermal maturity may have an impact on some redox-sensitive TMs such as Mo and V concentrations in marine sediments. Additional samples spanning higher maturities will need to be included because there is a possibility that an increase in thermal maturity may lead to the release and liberation of some redox-sensitive TMs from the organic matter (OM) directly. Remineralization and decomposition of OM with thermal maturity advance could release sulfur as a source of thermogenic HS, which could accelerate pore water/rock interaction and authigenic Fe-sulfides. This could enhance the capability of uptaking of most of the redox-sensitive TMs and increase their concentration in pore water.
在非常规巴肯源岩的不同热成熟度水平下采集了样本。利用程序升温热解衍生的参数、固体沥青反射率、类脂组显微组分紫外荧光以及核磁共振光谱作为不同的热成熟度指标，以便将对氧化还原敏感的痕量金属（TM）浓度与成熟度变化进行比较，并揭示任何可能的关系。将对氧化还原敏感的痕量金属与总有机碳进行比较，揭示了巴肯页岩沉积环境中存在缺氧/富硫环境。尽管一些痕量金属（钒和钼）与本研究中使用的一些热成熟度指标呈现出略微正相关，但其他对氧化还原敏感的痕量金属与成熟度之间的相关性呈中性。总体而言，本研究表明热成熟度可能会对海洋沉积物中一些对氧化还原敏感的痕量金属（如钼和钒的浓度）产生影响。由于热成熟度的增加有可能直接导致一些对氧化还原敏感的痕量金属从有机质（OM）中释放出来，因此需要纳入跨越更高成熟度的额外样本。随着热成熟度的提高，有机质的再矿化和分解可能会释放出硫作为热成因硫化氢的来源，这可能会加速孔隙水/岩石相互作用以及自生硫化铁的形成。这可能会增强对大多数对氧化还原敏感的痕量金属的吸收能力，并增加它们在孔隙水中的浓度。
