Estimation of Original Oil in Place & Aquifer Characterization of Ghani Field – Farrud Reservoir

Abstract

The material balance MB method is a powerful technique used to study reservoir performance and describing 
the important properties of the reservoir, including the estimates of original oil in place, and the strength of 
aquifer. It also provides the understanding of drive mechanisms at work, such as solution gas, water influx, and 
gas cap.  
This study aims to determine the original oil in place of the Farrud reservoir using both Volumetric & Material 
Balance methods using MBAL Software. Also, diagnostic the aquifer influx presents into the reservoir and 
their strength. Two scenarios involved in this study; the first scenario is building a reservoir model without 
aquifer connecting. The second scenario, three aquifer models were selected to achieve the matching between 
observed reservoir and simulation data.  
The Original Oil in Place Ghani-Farrud reservoir estimated by volumetric method was 735.24 MMSTB and 
the material balance used by Campbell Method was 920.8 MMSTB, the different between two values was 
about 21.8 %; that due to the uncertainty and lack of the data collected at the early lifetime, as well as the 
heterogeneities in the average reservoir parameter calculations. MBAL software led to the best analytical 
Matching between measured reservoir and simulation pressure which is improved by Hurst-van Everdingen 
Modified model with minimum standard deviation of 0.635. Based on the diagnostic plot of the Campbell, the 
a moderate strength aquifer is associated with the Farrud reservoir model. The Hurst-van Everdingen Modified 
model described the aquifer properties.