- Some of the main questions that could be answered by geochemistry, analytical programs and studies during appraisal relate to oil quality and fluid properties, source rock type and maturity indicators from oil and gas geochemistry, secondary or post-accumulation in-reservoir processes affecting fluid quality and/or volume of the accumulation, like biodegradation, water washing, trap leakage due to evaporative or migration fractionation. We'll discuss these topics in the following slides.