[CCoE Notice] Ph.D. Dissertation Announcement: September 4, 3:00p

[Grayson, Audrey A]

PhD Dissertation Announcement

Study of Dielectric Logging Tools and Dielectric Properties of Rocks

Yinxi ZHANG

Date: Sep 4th, 2014

Place: W342

Time:  3:00 pm to 4:00 pm


Committee Chair:       Richard Liu

Committee Members:
Donald Wilton
David Jackson
Thomas Holley
Heidar Malki

Abstract:  In the past a few decades, dielectric dispersion has been observed from core data. Dielectric tools are mainly used for identifying fresh water zones from oil or gas bearing formations. New generation dielectric tools are also used in detecting shale reservoir, heavy oil, and residue oil in invasion zones. This dissertation investigates both design and simulation of novel array dielectric tools and dielectric constant of formation cores by lab measurements.

A multi-component, multi-spacing array dielectric tool working at 5 different frequencies in the range of 10 MHz to 1 GHz is studied. It covers the frequency gap between propagation tools and conventional dielectric tools. Tool sensitivity is carefully investigated to demonstrate tool capability in exploring formation properties including permittivity, conductivity, dipping and anisotropy. Meanwhile, tool simulations with COMSOL provide comprehensive evaluation of tool performance. It is found that from the simulation results, influence from the tool pad and borehole mud can be negligible when the tool is pushed against borehole wall. However, existence of mudcake and invasion would affect the measurements as well as depth of investigation. In addition, vertical resolution is studied for different formation conditions. The designed tool is proven to be able to detect thin resistive beds or beds with high dielectric constant.

Practical core measurements for dielectric constant and conductivity were also conducted in this dissertation, a parallel plate system is used for the study. Relative dielectric constant and conductivity are measured in a frequency range from 10 KHz to 1GHz. Measured data agree well with the resistivity log inversion results, and large dielectric enhancement at the induction frequencies is observed. Based on the measurement results, dielectric and conductivity corrections are applied to the original log to correct the errors caused by dielectric dispersions.

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