Integration of geochemical data, well logs and seismic sections for source rock characterization of the Albian Kazhdumi Formation in the central Persian Gulf basin, South Iran

Abstract

This study presents indirect methods of source rocks characterization by integrating geochemical data with well logs and seismic inversion results. Well logs and seismic data are commonly more available than scarce geochemical data in oil and gas fields. Combining high vertical resolution well logs with high lateral resolution seismic data generates some enhanced geochemical data on inter-well spaces where no well is drilled.Acoustic impedance was obtained and utilized for the TOC prediction and source rock detection because of its good correlation with geological parameters such as the lithology and fluid contents. A cross-plot of log-derived water saturation versus acoustic impedance successfully differentiates source from non-source rocks based on geological variations of lithology, porosity, formations density, and the TOC content. The impact of the TOC content on acoustic properties was elaborated in the next step. Acoustic impedance is obtained as the most important seismic attribute for the TOC prediction. Well logs and seismic data are integrated to predict the TOC logs from seismic data. First, seismic data were inverted to obtain the acoustic impedance. Then, the produced acoustic impedance was used as a seismic attribute for the TOC prediction. The outcome is used to illustrate and follow the TOC variation to distinguish source rocks in the oil and gas fields. The study is carried out in the Cretaceous succession in three hydrocarbon fields in the central part of the Persian Gulf to observe the TOC variations in the Albian-aged Kazhdumi Formation.