Chemical Composition of the Mineral Matter of the Attarat Um Ghudran Oil Shale, Central Jordan

Abstract

The concession area of the Jordan Oil Shale Energy Co (JOSE) is located in the southern border zone of the Attarat Um Ghudran deposit, next to the Wadi Maghara deposit, both consisting of marinite type oil shale (OS). These deposits of the Upper Cretaceous to Lower Paleogene Muwaqqar Chalk-Marl Formation form a huge north-southward elongated oil shale basin in Central Jordan, with resources over 55 billion tons. JOSE has drilled a regular grid of boreholes with a full coring of the up to 90 m thick OS seam and its lower and upper contact layers. Visually, the OS unit is a rather homogenous dark-colored (grey, black, brownish grey) succession of finely bedded (laminated) kerogen-bearing carbonate rocks that has been in earlier papers described as a uniform lithological unit. The aim of the geological and lithological studies of the JOSE exploration area was (i) to investigate the vertical variation of OS composition and, if present, to define layers within the OS unit, and (ii) to identify lithological varieties and chemical composition of OS present in different layers.On the basis of field evidence, downhole gamma-logging, chemical analyses and other criteria, an original detailed scheme of the layered structure of oil shale and barren rocks was introduced. A total of eight OS layers (indexed as A, B1, B2, C, D, E1, E2, E3) and at least four barren dolomitic limestone interlayers were distinguished. The present publication is dedicated to the chemical study of the layers and the total OS seam. A representative gapless collection of 632 conventional core samples from 12 cores serves as the base for the comparative study of the layers. Two main (SiO 2 , CaO) and two subordinate chemical (Al 2 O 3 and P 2 O 5 ) components of the mineral matter (MM), and loss on ignition (LOI 500 °C) approximately reflecting the content of organic matter (OM), are the basic variables discussed. Contents of SiO 2 and CaO always show negative correlation, 19whereas local enrichment with Al 2 O 3 and P 2 O 5 occurs in certain interbeds. OM content in samples has no strong correlation with mineral matter abundances. The eight distinguished OS layers comprise both those strongly enriched in CaO, or oppositely in SiO 2 . The layers differ in rate of internal heterogeneity reflected in variation of standard deviation values. With rare exceptions, the barren limestone interlayers are dolomitized, strongly enriched with MgO and depleted of CaO. The database on the distribution of mineral compounds and trace elements serves for the 3-D block modelling of the deposit composition. However, further data analysis is required for the understanding of lateral changes of the layers' mineral composition, and geological and geochemical structure.

Illuminating and optimising a three‐dimensional model of an oil shale seam and its volume distribution using the transient electromagnetic induction method, central part of Jordan

“…Visual core sample examination, as well as x-ray diffraction and scanning electron microscope studies for the AUG area (Puura et al 2016), reveals oil shale as a dark grey to a brownish grey succession of laminated kerogen-bearing units. The highly carbonate layer of the oil shale seam is characterised by two main types of structure and texture: first and the most common is laminated to almost-massive mudstone composed of variably calcareous to siliceous minerals and kerogen with subsidiary clay minerals; and second, the infrequent, dense alternation of thin beds of mudstone at certain levels, including a millimetre scale of dominant carbonate grain-bearing wackestone or packstone lenses.…”

“…Puura et al (2016) documented eight layers where kerogen is infrequently varied between mudstone, packstone, and wackestone. Puura et al (2016) documented eight layers where kerogen is infrequently varied between mudstone, packstone, and wackestone.…”

“…The oil shale seam in the study area is intrinsically anisotropic as it consists of laminated kerogen-bearing layers of calcareous to siliceous mudstone, sedimentological features entail digenesis, and varied mineralogical compositions. Puura et al (2016) documented eight layers where kerogen is infrequently varied between mudstone, packstone, and wackestone.…”

“…The oil shale has the potential to be one of the largest unconventional hydrocarbon resources in the world (Dyni 2010). Alali et al (2015) ranked Jordan's shale oil reserves as the sixth largest in the world, which will encourage Jordan's government to consider it as a future unconventional source of energy (Puura et al 2016). Further geological investigations may lead to an increase in this reserve estimate.…”

“…Further geological investigations may lead to an increase in this reserve estimate. Alali et al (2015) ranked Jordan's shale oil reserves as the sixth largest in the world, which will encourage Jordan's government to consider it as a future unconventional source of energy (Puura et al 2016).…”