CHARACTERIZATION AND GEOSTATISTICAL MODELING OF RESERVOIRS IN ‘FALAD’ FIELD, NIGER DELTA, NIGERIA

Abstract

This study was aimed at characterising and modeling some reservoirs in ‘Falad’ Field, Niger Delta, Nigeria. In mitigating the challenge caused by the heterogeneitic nature of the reservoirs, this work integrated the results from seismic interpretation, well logs and geostatistics to describe the reservoir properties of the inter-well spaces within the study area. Four reservoirs namely RES 1, RES 2, RES 3 and RES 4 were delineated and correlated across four wells. Their reservoir properties (lithology, net pay, net to gross (NTG), porosity, permeability and water saturation) were determined in which two reservoirs i.e. RES 1 and RES 2 with the best quality were picked for modeling after ranking. Structural interpretation of the field was carried out using 3D seismic data, nine faults were mapped (F1-F9) and the fault polygon was generated. Structural and property modeling (net to gross, porosity, permeability, water saturation and facies) were distributed stochastically within the constructed 3D grid using Sequential Gaussian Simulation, Sequential Indicator Simulation and Gaussian Random Function Simulation algorithms. The average determined porosity, permeability, NTG and water saturation with respect to each reservoir from RES 1 to RES 4 were 19.5%, 21.3%, 21.3%, 20%; 461.75 md, 814.5 md, 585.75 md, 570 md; 51%, 41%, 37%, 13%; and 24%, 41%, 48.8%, 46.9% respectively. The reservoir structural model showed two of the major faults mapped (F1 and F3) oriented in the SW-NE direction while the other one (F4) is oriented in the NW-SE direction. The study has been able to show from the structural maps and models new prospective areas i.e. some of the western part of the study area and also subsurface information for future field development.