Evaluation of Petrophysical Properties in the Ak Field of the Niger Delta Province of Nigeria Using Integrated Data

Abstract

The AK field is an oil field draining the Agbada Formation, one of the three units of the Niger Delta Province, which started forming about 50 million years ago. Reservoirs from the AK field are sandstones and are located in the central offshore area of the Niger Delta. The sedimentary basin consists of thick succession of non-marine and shallow marine deposits. Reservoir modeling is often associated with uncertainties that lead to inadequate description of the reservoir and inappropriate prediction of field performance. Various techniques are being developed to reliably predict reservoir properties for appropriate reservoir characterization and field performance respectively. The reliability with which this can be achieved is tied to validating the data acquired from one method of investigation with another. Amongst the various methods are seismic inversion and well integration. The case study for this research is the AK field of the Niger Delta Province. Well log data for thirteen (13) wells and seismic volume spanning the field are collected and analyzed to predict water saturation, porosity, permeability, shale volume and net-to-gross sand distribution. The analysis was performed using Schlumberger-Petrel software. Multiple inter-wells data sets acquired from well logs and seismic survey from the field were tied together to estimate petrophysical properties. A Geological model comprising structural and stratigraphic framework for the AK field strata was constructed by combining data from 13 well logs and a seismic volume spanning the areal extent of the field. The property distribution within the reservoir was achieved by employing geostatistics - Sequential Gaussian Simulation (SGS), Variogram and trend maps.