Geomechanics and Geoenergy Journal

Geomechanics and Geoenergy Journal

Determination of The Oil Ring in the Pushed-aside Reservoirs, Using Seismic Data and Petrophysical Logs- A case study from an oil reservoir in the south Iran

Document Type : Original Article

Authors
karim Khorsandpour 1
Ali Misaghi 2
Mohsen SeyedAli 3
1 , Department of Applied Geology, Faculty of Earth Sciences, Kharazmi University
2 Department of Applied Geology. Faculty of Earth Sciences, Kharazmi University
3 Department of Geophysics, Iranian Offshore Oil Company
10.22107/jpg.2024.464663.1236
Abstract
Usually in anticline structures where the presence of hydrocarbons has been proven, gas and oil are laterally to each other, which due to the difference in density, the gaseous layer at the top (peak) and the oil fluid at the bottom of the anticline structure. Drilling is done at the points that include the maximum height of the oil column and usually these points are at the top of the structure. However, in some special cases, and in the “Pushed-aside” oil reservoirs, it has been seen that the oil column is located in the edges of the anticline structure next to the gas layer at the top, but due to drilling on the center of this structure and the well entering the bottom layer through the gas layer, the oil in the edges of the structure remains in place without extraction. The phenomenon that oil is in the form of an oil ring (donut-shaped) and appears to have been pushed from the center to the sides by the gas cap and the thermodynamic conditions of the oil column reservoir can have a profound effect on the detection and amount of oil in the reservoir.
In this research, by using the well logs and seismic data, the remaining oil ring of Aboozar oil field and the fluids boundary of the upper horizon of the reservoir were determined by using the analysis of amplitude variation with offset. Direct modeling results can be used to plot AVO curves and detect classification of AVO anomalies. With Pre-stack inversion, using different AVO Attributes and the LMR parameters the fluid type and lithology of the upper horizon of the reservoir were identifiable. The results indicate the presence of oil in the proximity of gas in the Upper Asmari Formation, as the oil ring.
Keywords
Amplitude Reflection Variation with Offset
Pre-Stack Inversion
AVO Analysis
AVO Attributes
LMR Parameters
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Geomechanics and Geoenergy Journal
Volume 7, Issue 2
Winter 2024
Pages 53-67