Geochemical and gas chromatography study on oil produced by hydrous pyrolysis from kerogen type II oil shale samples in Ghali kuh Mountain area of Lorestan Iran

The first discovery studies on oil shale in the Zagros Basin are in the Qali Kuh region in Lorestan province. The results of their studies showed that Sarglu Formation in Qali Kuh region has the characteristics of oil shale. There are different methods for evaluating rocks in terms of hydrocarbon generation potential. One of the best methods is to use hydrous pyrolysis. This method can determine the production capacity of oil shales by simulating near-reality conditions.

In this study, the hydrocarbon generation potential of Sarglu Formation has been studied using hydrous pyrolysis method. Therefore, for this study, hydrous pyrolysis cell was performed according to the desired specifications. Also, gas chromatography and carbon isotope analysis were performed to complete the studies on the samples.

Hydrous pyrolysis test for oil shale samples of Qali Kuh region is performed at six temperature points of 330, 310, 290, 270, 250 and 350 ° C for 72 hours. Most hydrocarbon generation in this experiment occurs at 330 ° C. At 330 ° C, the percentage of gaseous hydrocarbons and non-hydrocarbon gases (CO2, N2, H2) is set as a bar graph in Figure 1.
 
 
Fig. 1. percentage of the frequency of different hydrocarbon and non-hydrocarbon compounds in the gaseous product of aqueous pyrolysis at 330 ° C
 
The rock-eval study on the sample of oil shale studied shows that the type of organic matter in the sample of Type II kerogen (Figure 2).
 
 
Fig. 2. Diagram of hydrogen index versus total organic carbon to determine the type of organic matter
 
In Figure 3, the Pri / n-C17 diagram is plotted in terms of Phy / n-C18. The above data is shown as a blue dot in Figure 3, which shows that the organic matter of samples is mainly of type II kerogen and was deposited in the marine sedimentary environment with reducing conditions.
 
 
Fig. 3. Graphs of ratios of paristan and phytan biomarkers to normal alkanes and sediment environment indices and kerogen types
 

This study showed that the highest oil generation occurs at a temperature of 330 ° C, which is equal to 739 mg of oil per 50 g of sample. According to a study conducted in this region, 15.72 liters of oil is generated per ton of oil shale. In fact, the above study clarifies that with the help of laboratory methods such as hydrous pyrolysis, it is possible to evaluate the production of hydrocarbon compounds such as oil from oil shale samples on a very small scale. This facilitates calculating and accurate estimating of oil production on a large scale.