Estimating of organic porosity in the Silurian shales around Hendek (Sakarya, NW Anatolia) using the rock-eval pyrolysis data

In recent years, in unconventional resources, organic porosity developed from thermal maturation of original organic matter has been determined as an important storage capacity. In this study, the organic porosity development of the Silurian Fındıklı Formation consisting of shales in the northwestern Black Sea region of Hendek (Sakarya) district was investigated. Rock-Eval pyrolysis data show that the TOC values of the Fındıklı Formation vary from 0.04 to 1.26 wt % and HI values range from 0 to 40 mg HC/g TOC. These measured values were evaluated together with other parameters calculated from Rock-Eval pyrolysis and the samples were determined to contain Type IV kerogen and highly thermally mature. The pyrolysis results of the Ereğli Gülüç, İğdir-Örenköy and samples from Hendek-Kocaali measured sections were considered due to distribution of graptolites and the appearance of Orthoceras fossils. The lower TOC values less than 1 % (wt %) imply that the Kocaali units were deposited more oxic conditions and their age should be Middle-Late Silurian. Organic porosity values were determined according to 6 different assumed coreesponding to marine type II kerogen HI data (250, 300, 350, 400, 450, 475). Total organic porosity ratio calculated in original organic matter or kerogen are between 13.74 and 28.82%. It was concluded that the increasing trends in TOC values from Ereğli to İğdir had no direct effect on organic porosity values.