Maximize Mass Spectrometer Mud Gas Data-Experienced Analysis Matters

Abstract

Modern surface logging of mud gases at the well site while drilling often makes use of a mass spectrometer. Today's portable mass spectrometers have detection capabilities which far exceed traditional gas chromatography. While the mass spectrometer's mud gas data provides a tremendous amount of information, it is not fully understood and greatly underutilized. The mass spectrometer gas curves can provide useful information given by more than visual inspection of individual curves, but a much greater understanding of their meaning and use comes with statistical analysis, ratios, cross-plots, and experienced interpretation. Statistical analysis of mud gas data can reveal reservoir qualities not otherwise readily observed. For example, normalizing mud gas values and direct comparison with various molecular weight species can begin to characterize hydrocarbon compositions and isolate zones of interests. Standardizing mud gas values and comparison with rate of penetration can establish a mean value across a well's data set and allow gas curves to be evaluated as they deviate from average which can be indicative of particular “sweet spots” or even depleted sections. Applying gas component ratios and cross-plotting the mass spectrometer data set provides convincing evidence for zones of “likeness” or “unlikeness” which may signal compartmentalization, compositional variations, water saturation, secondary porosity/permeability and other notable geologic conditions.

AAPG Datapages/Search and Discovery Article #90193 © 2014 Rocky Mountain Section AAPG Annual Meeting, Denver, Colorado, July 20-22, 2014