Abstract

Geostatistical modeling is performed on the “TMB field” in the offshore area of Niger Delta using 2D seismic data. The goal of the study is determine interval velocity by using geostatistical modeling; and calculate the volume of the reservoir according to different Oil-Water-Contact (OWC) whose uncertainty was characterized by a given probability distribution. The models are completely consistent with the observed vertical and lateral distribution of the structural and petrophysical parameters. The probability distribution of Stock Tank Oil Initially In-Place (STOIIP) is obtained with 3D operator layer-based inversion scheme. After the modeling, estimation of unbiased volumes is carried out and the risk associated with the volumes is quantified. Regression analysis based on geologic zones showed that geological and petrophysical modeling results exhibit a correlation between increasing N/G and increasing STOIIP, as well as between the increasing porosity and increasing STOIIP. STOIIP increases as the value of N/G and porosity increase. The major steps in the geostatistical modeling procedure are illustrated with an example of depth conversion from the TMB field. This study shows that it compares favourably with other techniques like linear velocity modeling.

Key words: Probability distribution, geostatistical modeling, reservoir property, porosity, water saturation, gross rock volume, interval velocity, net-to-gross.