Rock Physics Models and Seismic Inversion in Reservoir Characterization, “MUN” Onshore Niger Delta Field

James Mwendwa Munyithya,Tamunonengiyeofori Dagogo,Chukwuemeka Ngozi Ehirim

doi:10.4236/ijg.2019.1011056

Abstract

Rock Physics Modelling and Seismic Inversion were carried out in an Onshore Niger Delta Field for the purpose of characterizing a hydrocarbon reservoir. The aim of the study was to integrate rock physics models and seismic inversion to improve the characterization of a selected reservoir using well-log and 3D seismic data sets. Seven reservoir sands were delineated using suite of logs from three wells. In this study, the sand 4 reservoir was selected for analysis. The result of petrophysical evaluation shows that the sand 4 reservoir is relatively thick (62 ft) with low water saturation (0.33), shale volume (0.11) and high porosity (0.32). These results indicate reservoir of good quality and producibility. Cross-plot of property pairs (acoustic impedance (Ip) vs. lambda-rho (λρ) and mu-rho (μρ) vs. lambda-rho (λρ) color-coded with reservoir properties reveals three distinct probable zones: hydrocarbon sand, brine sand and shale. Results show that low Ip, λρ and μρ associated with hydrocarbon charged sands correspond to low Sw and Vsh and high &#216. The integration of rock physics models and inverted rock attributes effectively delineated and improved understanding of already producing reservoirs, as well as other hydrocarbon charged sands of low Sw, Vsh, and high &#216 to the east of existing well locations, which indicate possible by-passed hydrocarbon pays. The results of this work can assist in forecasting hydrocarbon prospectivity and lessen chances of drilling dry holes in MUN onshore Niger delta field.

Highlights

The knowledge of elastic rock properties in reservoir characterization is important as they closely relate to quantitative reservoir properties
The results of this work can assist in forecasting hydrocarbon prospectivity and lessen chances of drilling dry holes in MUN onshore Niger delta field
The wells were analyzed for lithology and fluid using gamma ray and resistivity logs

Summary

Introduction

The knowledge of elastic rock properties in reservoir characterization is important as they closely relate to quantitative reservoir properties. Rock physics plays an important role in the hydrocarbon prospecting as a bridge between these elastic parameters and reservoir properties, providing the basic relationships between reservoir seismic response and lithology, pore fluid, pressure, temperature and porosity of the reservoir [1]. Apart from characterization, the changes in reservoir properties caused by production can be monitored using these elastic rock parameters. Ground subsidence due to hydrocarbon extraction was inferred from evaluating density, lambda-rho and acoustic impedance changes [3]. Both observations show that elastic rock properties can be used in exploration and production stages to understand the physical behavior of the reservoir

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Conclusion