ABSTRACT: Improved Cuttings Analysis by Thermal Extraction Chromatography

SEGREST, CHARLES, and JOHN SEBIAN, Core Laboratories, Midland, TX

Thermal extraction chromatography (TEC) and relative hydrocarbon fluorescence (RHF) provide improved assessment of hydrocarbon productive potential from drill cuttings, full cores, and percussion or drilled sidewalls.

Both rock quality and hydrocarbon content are evaluated by both techniques. RHF is used as a screening tool for TEC sample

selection. Identification of productive intervals, oil-water and gas-oil contacts, type of production, maturity of oil, secondary contacts, and apparent gravity can be assessed.

Fluorescence (RHF) is determined by use of a digital fluoroscope. Total fluorescence intensity and "rate of cut" or rock quality are evaluated over large gross intervals. Zones of interest are identified and a more thorough investigation of these zones is done using TEC. In TEC analysis, the hydrocarbon content in the rock sample is pyrolized into an FID chromatograph using a megabore column. The characteristic hydrocarbon fingerprint is developed and evaluated. TEC is more definitive than RHF, but both may provide comparable interpretations, in which case, future analysis can limit use of TEC and depend more on RHF for interpretation purposes, reducing the overall cost of analysis. This technique can enhance electric logging interpretations in difficult to predict formations. In addi ion, the nature of the analysis techniques removes operator sensitivity in the interpretation of fluorescence and "rate of cut" as described by mud loggers. This allows comparisons to be made to past measurements which improves the interpretative value of these techniques.

The methods described are both cost effective and rapid, providing data in a completion time framework. Examples of past measurements are given and related to actual production. Discussions also focus on interpretation of the data.

AAPG Search and Discovery Article #91018©1992 AAPG Southwest Section Meeting, Midland, Texas, April 21-24, 1992 (2009)