SRA-TEPI™

Assessment of the type of hydrocarbons present in rock cuttings or cores can be achieved through a combination of thermal extraction gas chromatographic (TEGC) fingerprinting and analysis of physical properties such as API gravity and sulfur content. TEGC fingerprinting is done using an SR Analyzer–TEPI™ ( Thermal Extraction Pyrolysis Inlet ) instrument. Thermal extraction using the SRA-Thermal Extraction Pyrolysis Inlet (SRA-TEPI™) is a technique where volatiles are vaporized from a solvent matrix strictly by heat. It is different from solvent extraction in that no sample preparation is required. It is different from thermal desorption in that the vaporized products are eluted directly onto a GC column rather than an adsorbent, thereby enhancing reproducibility. Thermal extraction and elution into a GC column is comparable to syringe injection. Using the TEPI, the pyrolysis process is carried out on solid, semi-solid or liquid samples and thus heat is used to decompose complex organic matrices such as kerogen into smaller, easier to analyze fragments. For instance, high molecular weight synthetic or geopolymers can be cracked to low molecular weight compounds that are GC amenable. This allows study of structure and decomposition products. Rock oil extracts containing various qualities of oil or contaminants have diagnostic Thermal Extraction Gas Chromatography fingerprints and so based on their TEGC fingerprints, identification and characterization to determine whether they are normal oil (mid 30’s API), biodegraded including pyrobitumen (15-20 API), condensate (>50 API), waxy oil (25 – 30 API), residual oil or contaminates such as diesel is achieved.

Using the SRA-TEPI™ an analyst can also use the hydrocarbon fingerprint and molecular ratios to evaluate rock-to-oil correlations, oil-to-oil correlations, maturity, migration pathways, reservoir connectivity, as well as to evaluate post generative effects such as water washing, thermal alteration, and biodegradation. One additional benefit of this technique is that since the hydrocarbons are volatilized from the rock by temperature there is little or no loss of light or gaseous hydrocarbons during the analysis.