Synthetic Array Curves from Dual Induction Logs

Hu, Guoyu ¹; Geldmacher, Ingo ¹
(1) Weatherford International, Houston, TX.

Description

The traditional dual induction tool makes two apparent resistivity measurements at two different depths of investigations. In Weatherford’s Simultaneous Triple Induction (STI) instrument, these are combined with an SFL to deliver three curves. Typical presentation of these measurements is by means of an enhanced resolution algorithm. However, it is more desirable to illustrate multiple depths of investigation curves with a variety of fixed depths of investigations. Based on the use of multiple frequencies at which the STI operates, we can derive an additional “synthetic” array logging response.

Application

This is achieved through a non-linear processing approach. Here, rigorous non-linear 2D modeling is used to forward model the induction tool response. The synthetic array curves are an improved version of the presentation of the traditional dual induction measurement at multiple frequencies by creating a “pseudo” array response. Usefulness and limitations of the method will also be discussed.

Results

We will show how synthetic array curves are generated through modeled examples and on field test examples.

Significance

Combined use of multi-frequency data for traditional induction tools, e.g., the dual induction tools, has not been adequately addressed at least in published work. Our work shows that there is information untapped for in this area and with understanding of its limitations, more information on the near borehole region can be inferred than using the single frequency approach.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.