Dielectric Constant Logging, A Salinity Independent Estimation of Formation Water Volume

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines. Abstract A knowledge of the dielectric constant of earth materials provides a potential method of directly measuring formation water saturation. Dielectric logging has been studied theoretically and experimentally in order to supply this valuable knowledge. Laboratory core measurements, theoretical borehole-system computer models, instrument design and a detailed field example are combined to illuminate the concepts and demonstrate the value of dielectric constant logging. Introduction An open hole logging method which directly distinguishes oil from water in formations having low or unknown water salinity has been needed for many years. A potential technique for solving this problem relies upon a determination of the dielectric constant of the formation. Dielectric constant is a basic electrical property of matter for which oil and water have distinctly different characteristics. It is measured in units of farads per meter. It is well known that resistivity log interpretations are dependent upon a knowledge of formation water salinity. Unknown or variable salinity often leads to ambiguity in the log interpretation. Dielectric constant measurements can circumvent this problem because the formation dielectric constant is primarily determined by the water volume, not the water salinity. Large water volumes produce high dielectric constant values, and small volumes produce low dielectric values. produce low dielectric values. Efforts to build logging systems which measure formation dielectric constant have been underway. Russian scientists have been active in this field for several years and have published papers on the subject. published papers on the subject. The various aspects of dielectric logging have been discussed separately in these publications.