An Integrative Modeling Approach to Estimating Volume of Generated Oil from Lower Cretaceous Sulaiy Formation in Southern Iraq

Basim Alkubaisi

doi:10.46717/igj.54.1c.9ms-2021-03-29

Abstract

Thermal maturity and petroleum generation capacity of the source rocks of Lower Cretaceous Sulaiy Formation were studied and evaluated via modeling the thermal maturation of ten wells in this study by using the Arrhenius equation for chemical reactions or (time-temperature index of thermal maturation). A thermal maturation map of the Sulaiy Formation shows that it a high maturity level increasing eastward; also, the geochemical analysis indicated suitable organic content in quantity and quality to generate hydrocarbons. The onset of oil migration from the Sulaiy Formation is calculated by this study to be at the end of Lower Eocene time (53 million years ago), and as it is a late hydrocarbon generation and migration; thus indicating mainly vertical migration paths. According to quantitative estimation, the oil generated and migrated vertically from the Sulaiy Formation towards the Lower Cretaceous reservoirs in southern Iraq estimated at 42.6 x 109 bbl. This study elevated the status of the Sulaiy Formation to a major source of oil tapped in the Lower Cetaceous reservoirs of southern Iraq.

Highlights

The process of identifying oil generating rocks is considered within any zone is a basic and effective tool in the study of the hydrocarbon potential of that zone and is an important factor in reducing the risk factor in exploratory process
The thermal maturation values calculated according to Arrhenius equation that has been used for Iso-thermal maturation (Iso-TTI) mapping of Sulaiy Formation (Fig.10)
The projection of the calculated and observed TR values versus depth is used to determine the main zone of oil generation within the Sulaiy Formation which is determined at depth (4480-4510 m.) (Fig. 9).according to the above results we can consider the rocks of the Sulaiy Formation as a well-supplied source of oil for southern Iraq reservoir and some surrounding areas

Summary

Introduction

The process of identifying oil generating rocks is considered within any zone is a basic and effective tool in the study of the hydrocarbon potential of that zone and is an important factor in reducing the risk factor in exploratory process. The black shales between the limestone beds can be considered as a good source for hydrocarbons generation because the shales are rich in organic matters and have reached the level of maturation zone (Mamaseni, 2020). The thickness of it ranging between 100-400m and decreasing until wedge out to the west. Determining the thermal maturation level and oil generation prospects depends on one of the following principles: The rate of chemicals reaction doubles by 10oC for each heat increment (Waples, 1980). The second principles, which was adopted in this study, is based

Methods

Results

Conclusion