The Benefits and Application of Rapid Mineral Analysis Provided by Fourier Transform Infrared Spectroscopy

Abstract

ABSTRACT Quantitative mineralogical information is critical to the characterization and exploitation of hydrogarbon reservoirs. Fourier transform infrared (FTIR) spectroscopy can now routinely provide this information. The instrumentation used to perform FTIR spectroscopy does not require ionizing radiation or special utilities, making the instrument more versatile. Using a computer to interpret the raw data removes the subjectivity prevalent in other techniques. The major advantages of FTIR over other analytical methods are that it is rapid (5 to 6 samples per hour) and cost effective. Furthermore, FTIR can be performed on a minimal amount of sample. Typical samples such as drill cuttings, trimmed ends of core plugs, and sidewall core samples are suitable. FTIR is a valuable mineral analysis technique, whether used by itself, or in conjunction with other investigative methods. Specifically, its rapid nature lends itself to many different applications. Rapid, quantitative mineralogy may be used to calculate matrix density, yielding more reliable porosity calculations from compensated density logs. Correction of Vsh from gamma-ray logs can be done using the total clay and potassium feldspar content given by an FTIR analysis. In some areas, a timely mineral analysis may identify low resistivity "pay zones" in clay rich areas. Rapid mineral determination can be useful in quickly determining formation breaks or marker beds, and delineating zones of cementation. This type of information also provides an important first step in formation evaluation. Mineral composition, coupled with scanning electron microscopy, may identify fluid-sensitive minerals and potential production problems. Examples of such applications as described above are given in this paper.