Petrophysical Reservoir Characterisation and Flow Unit Assessment of D-3 Reservoir Sands Vin Field, Niger Delta

Petrophysical evaluation and flow unit assessment of the D-3 reservoir sand in the Vin field, offshore Niger Delta has been performed. The aims of the study are to assess the reservoir quality and flow units in the field through the integration of results from core analysis, production data, seismic data, and petrophysical parameters. Well log suites from 22 wells comprising gamma ray, resistivity, neutron, density, seismic data, and ditch cutting samples were obtained and analyzed. Petrophysical evaluation was carried out using various petrophysical computations. Field wide correlation from the western to the eastern part of the field was also carried out. Assessment of the flow unit was done using Flow Zone Indicator (FZI), Stratified Modified Lorenz plot, porosity-permeability cross plot and Winland technique. Field wide correlation revealed that the reservoir is laterally extensive and thins towards the east. Reservoir rock qualities were generally very good with Volume of shale ranging from 0.08 to 0.14, with an average of 0.11. Porosity values ranges from 0.22 to 0.40 with an average value of 0.34 while permeability values is between 130mD to 10,000 mD, with an average value of 2692 mD. Average water saturation values ranges from 0.17 to 0.42, while the average net to gross ratio is 0.89. The bulk water volume values are nearly constant, meaning the reservoir is homogenous and at irreducible water saturation. This implies that the reservoir can produce water-free hydrocarbon. The Stratified Modified Lorenz (SML) plot revealed three flow units with two high speed zones (FZ 1 and FZ 3) and one low speed zone (FZ 2). Based on the FZI, three flow units (FZ-1 to FZ-3) were identified in the reservoir with FZ-1 having the best reservoir quality. Winland technique presents three Petrofacies (Mega porous, Macro porous, Micro porous). Porosity-permeability cross plot also revealed three distinct facies based on ditch cuttings description. These facies are: U1- fine grained well sorted sandstone, U2- very fine grained well sorted sandstone, and U3- very fine grained shaley sandstone. Each of these facies is associated to a unique flow unit meaning that different depositional environment and diagenetic processes control the geometry of the reservoir and consequently the flow unit index. By modelling the reservoir behaviour and simulating their behaviour, uncertainties associated with field development in the Vin field and fields in the eastern Niger Delta will be reduced from the outcome of this study