A Case Study of Permeability Modeling and Reservoir Performance in the Absence of Core Data.

Abstract

Unavailability of core data in most Niger delta wells makes pertinent the need for a reliable permeability distribution. This paper accounts for how permeability was modelled in a reservoir without core data in the Niger Delta by using five empirical approaches namely, Timur, Coates, Tixier, Udegbunam and also a correlation generated from core data of a nearby field. The five permeability results from the five approaches were used in building five different 3 D geological models. Flow simulation was carried out for all the models to analyse their flow peformance. The permeability distribution from the correlation generated from the nearby field core data yielded a higher oil recovery. Introduction The permeability of a rock is one of the most important parameters neccessary for effective reservoir characterization and management. Therefore accurate knowledge of its distribution in the reservoir is critical to accurate production performance prediction. During primary depletion, areal variation of permeability influences oil recovery. Permeability measurements from cores are direct measurement of these properties. But a reservoir without core data is often associated with uncertainties as these properties have to be log derived. Permeability of a formation is affected by factors such as porosity and pore space characteristics, types, amount and distribution of clay minerals, rock matrix composition and size of matrix grains. Several authors have proposed models for permeability determination in an uncored reservoir using well logs. These models are based on correlation between permeability, porosity and irreducible water saturation. Irreducible water saturation being a function of the rock characteristics. The workflow consists of petrophysical evaluation, permeability estimation, 3D geocellular modeling, upscaling of fine grid models for flow simulation and dynamic modeling.