Exploratory Testing of a New Well-Logging Technique
Authors: Barrett K.E. , Lowery R.L. , Rowe A.M. 
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

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.

It is the purpose of this paper to describe a very simple instrumentation system that measures directly a single rock property its texture. This system uses a piezo-electric displacement probe to generate a signal as the probe traverses a formation rock simple. The signals generated by this transducer are analyzed by two different methods depending upon the gross characteristics of the formation. One method involves a frequency spectrum analysis of the output wave; the other method is based on the interpretation of the time history of the output wave. The equipment set-up used in these tests was relatively simple, using common laboratory instruments.

This work shows that unique texture properties exist and can be measured under ideal laboratory conditions by these two methods. The two methods were found to complement each other. For example, a vugular limestone gives a confusing frequency spectrum, but generally has a very distinctive time history.

Although the results are encouraging, considerable research will be required to design a system that will give optimum results in the adverse environment encountered in a well bore.

Introduction

Most well-logging techniques are based on measuring responses [or signals] that are influenced by such factors as the size of the wellbore, the drilling fluid, the formation matrix rock, and formation fluid content. These signals either are-generated by naturally occurring phenomena within the formation or result from an artificially created disturbance in the wellbore. In many cases it is extremely difficult to make a quantitative interpretation of these signals in view of the many variables involved. Even qualitative interpretation is difficult, as evidenced by the oversight of productive horizons.

The purpose of this study was to investigate the use of transducers to measure a single rock property its texture. Transducers have been successfully used to detect slight variations in surface roughness as evidenced by the success of high-fidelity crystal cartridges Also, stylus-type transducers are currently being used for surface roughness comparators. It seems logical that similar transducers could also be adapted to generate characteristic logs of formation rock.