Evaluating Uncertainty in the Volumes of Fluids in Place in an Offshore Niger Delta Field

The purpose of this work is to evaluate the uncertainty in the volumes of fluids in place in Fault Block A (Segment 3) of the G-1 Sands in the OND field located offshore Niger Delta. This would aid in business decision making and limiting risks which impacts in the development of a successful hydrocarbon exploration and exploitation program. The evaluation was performed in three parts: The first part was executed by building a grid-based model of the reservoir using Eclipse & Petrel. A 100 x 60 x 4 grid was built & faults were created in the model which delineated the reservoir into six segments. The second part of the study involved the calculation of petrophysical properties that affect the volumes of fluids in place & distributing them in the model. This was done by assigning various probability distribution functions to porosity, water saturation and net-to-gross; and calculating STOOIP for the three hydrocarbon zones using Monte Carlo simulation. One hundred realizations of STOOIP were generated for each zone in the reservoir. In the third part of the study, these realizations were plotted as histograms to determine the P10, P50 & P90 values of STOOIP, and these values showed that there was a general decrease in these values for each zone with increase in depth. This methodology can be applied to other reservoirs for proper planning in new and existing field development, as well as the understanding of management risks