Geochemistry plays a key role in oil and gas business and often, it has the reputation of providing the most economical way to establish the ground truth for any analytical work done to trace hydrocarbon presence. Conventional ways in determining hydrocarbon fluid type and flow potential such as wireline formation tester, optical fluid analyzer, well testing, downhole and surface fluid samples could be an advantage or a headache if delineation of hydrocarbon presence is masked by high contamination from drilling fluid or non-representative samples. Hence, geochemistry method offers a blessing in tracing the hydrocarbon presence. Methodology and principles of gas-chromatograph (GC) fingerprinting, case studies for application and value creation to the business are the scopes of this paper.

Examining the DNA and composition unique to each hydrocarbon fluid sample in the lab can be an intriguing process which requires shorter time compared to conventional analytical work. Requiring only few drops of hydrocarbon fluid, synthetic-based mud and base oil samples as input into the GC spectrometer machine, the unique chromatogram signature from each fluid will be overlaid onto each other for comparison and quantification of contamination level.

The case studies presented in this paper will highlight the key characteristics of live hydrocarbon signature as compared to the dead oil or drilling fluid signature which acts as the outlier or contaminant to the samples. Values created in terms of proving the hydrocarbon discovery, determination of potential well barrier leaks and refining well testing decision based on the fingerprinting results which involves stakeholder's interest will also be highlighted.

In a nutshell, application of GC fingerprinting to ascertain hydrocarbon fluid type is successfully proven, cost effective and technically viable approach. Recognizing the DNA and unique signature of each fluid will be an added advantage for short term and long term.

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