Evaluation of hydrocarbon generation in source rock using geochemical studies and 1D basin modeling in Kish field, northeast Persian Gulf

The Persian Gulf basin is one of the most important regions in terms of hydrocarbon resources in the world. The Kish gas field is located in the eastern part of the Persian Gulf.  The purpose of this paper is to assess the hydrocarbon generation potential and to model the burial and thermal history of source rocks in this gas field using Rock-Eval pyrolysis, vitrinite reflection, and a 1D model.

Methodology and Approaches:

In this study, 58 rock samples were selected from layers with high natural gamma ray in Pabdeh, Gurpi, Ilam, Lafan, Sarvak, Kazhdumi, Dariyan, Gadvan, Fahliyan, Surmeh, Neyriz, Dashtak, Dalan and Faraghan Formations for Rock Eval pyrolysis and vitrinite reflection. In addition, one-dimensional modeling of burial and thermal history was performed using PetroMod software (2011-Schlumberger) on well B of the Kish field.

The TOC and S1+S2 values vary from 0.16 to 1.59%, and from 0.08 to 4.16 mg HC/g Rock, respectively. Most of the samples have low hydrocarbon potential, only a limited number from Gurpi and Pabdeh show fair hydrocarbon generation potential. The samples with fair potential have kerogen type III and II/III with the low level of maturity. The one-dimensional modeling was performed on Pabdeh, Gurpi and Sarchahan source rocks. The thermal model was calibrated with corrected down-hole temperatures and vitrinite reflections. According to the model, Pabdeh and Gurpi are immature, while the Sarchahan is currently in the gas window. It has reached the oil and gas window since 160 and 120 million years ago, and produced 95% of its potential so far.