SEISMIC INVERSION FOR RESERVOIR CHARACTERIZATION IN UNCONVENTIONAL SHALE PLAYS

Abstract

This paper examines the use of seismic inversion as an evaluation method of the reservoir in unconventional shale plays. In the Eagle Ford, Bakken and Marcellus formations, and others that contain the Shale resources, the heterogeneity, anisotropy, and multi-mineralogy of the formation pose a special challenge. Seismic inversion is very important in the conversion of seismic reflection data to quantitative rock properties in the form of acoustic impedance (AI), shear impedance (SI), density, and elastic moduli that are important to detect important features of reservoirs like Total Organic Carbon (TOC), brittleness, and geo-mechanical properties. The research paper describes the process of seismic inversion that involves data conditioning, examination of well logs, AVO/AVA analysis, inversion, interpretation and combination with other geologic as well as operating data. It also talks about the main problems encountered during the characterization of shale reservoirs, such as poor vertical resolution owing to thin beds, complicated rock physics caused by mixture of mineralogy, high anisotropy and lack of well control. Regardless of these difficulties, seismic inversion can be used to give meaningful information on where to find sweet spots, well placement, and estimate of the volume of stimulated rock as well as avoid hazards. Finally, the paper highlights the significance of the latest inversion methods and combining them with rock physics models to become effective in the development and management of shale reservoirs.