Clay Minerals and Organic Matter from Deeply Buried Ordovician-Silurian Shale in Western Iraq: Implications for Maturity and Hydrocarbon Generation

  • Ali I. Al-Juboury Department of Geology, College of Sciences, University of Mosul, Iraq
  • Mohammed A. Al-Haj Department of Geology, College of Sciences, University of Mosul, Iraq
  • Adrian Hutton School of Earth and Environmental Sciences, Wollongong University, 2522 NSW, Australia
  • Brian Jones School of Earth and Environmental Sciences, Wollongong University, 2522 NSW, Australia
Keywords: Organic matter, illite-smectite, maturity, Ordovician -Silurian shale, Iraq

Abstract

The present work is conducted on the Paleozoic (Ordovician) Khabour and the (Silurian) Akkas shales in the Akkas-1 well of western Iraq. The study is aiming to determine the implications of clay mineral transformation, organic mineral distribution and maturity of hydrocarbon generation, using X-ray diffraction (XRD), scanning electron microscopy (SEM) in addition to organic matter concentrations. In the shale of the Khabour Formation, amorphous organic matter is common and includes various Tasmanite-type organic matter, vitrinite, inertinite, and bituminite. The main clay minerals observed include illite, chlorite, kaolinite, in addition to mixed-layer illite-smectite and rare smectite. In Silurian shale, high content of organic matter is recorded in addition to abundant vitrinite and low content of grainy organic matter (Tasmanites) and pyrite. Illite and kaolinite are commonly found in addition to chlorite and illite-smectite clay minerals. Conversion of smectite to mixed-layer illite-smectite (I-S) and an increase in vitrinite reflectance are commonly observed below 2500 m depth in the studied formations, which coincides with oil and gas generation. These results could be used as an indication of higher maturity and hydrocarbon generation in the deeply buried shale of the Khabour and Akkas formations in western Iraq.

Published
2020-11-28
How to Cite
Al-Juboury, A. I., Al-Haj, M. A., Hutton, A., & Jones, B. (2020). Clay Minerals and Organic Matter from Deeply Buried Ordovician-Silurian Shale in Western Iraq: Implications for Maturity and Hydrocarbon Generation. Iraqi Journal of Science, 61(11), 3017-3034. https://doi.org/10.24996/ijs.2020.61.11.23
Section
Geology