Identification of source of a marine Yamama oils using biomarkers and carbon isotope analysis, in Ratawi oilfield, southern Mesopotamian Basin, Iraq.

Abstract

Yamama Formation (Late Berriasian- Aptian cycle) is one of the main Lower Cretaceous carbonate promising reservoir in the Mesopotamian Basin, southern Iraq. The Yamama obviously is oil producing throughout Rumaila North, Zubair, Majnoon, West Qurna, Nahr Umr, Nasiyria, Abu Khima, Rafedain, Samawa, and Luhais oilfields southern Iraq.

Eight crude oil samples and fifteen source rock extract s from Lower Cretaceous Yamama and Mishrif formations from Ratawi and selected oilfields have been analyzed using Gas Chromatography – Mass Spectroscopy (GC-MS), to get biomarkers ratio in the branched, cyclic, and aromatic fractions, and carbon e isotope analysis. In addition, thirty rock samples from the Upper Jurassic and Lower Cretaceous sequences, have been subjected to source rock analysis.

Yamama Formation crude oils are interpreted as being sourced from:

Geochemical analysis of the Yamama source rocks indicate good quality source rock with fair to good total organic carbon (up to 4.5 wt% TOC) and rich in amorphogen, show good hydrogen indices and are likely to have charged Yamama reservoirs during the Miocene period.

The geochemical evidence suggests that the Yamama oils may have been sourced from the Lower Cretaceous Yamama Formation itself.

AAPG Datapages/Search and Discovery Article #90226 © 2015 European Regional Conference and Exhibition, Lisbon, Portugal, May 18-19, 2015