Geochemistry as a State of the Art Reservoir Investigative Tool

Compositional variations are observed in conventional and unconventional reservoirs worldwide due to various in-reservoir processes. Geochemical characterization of these variations in reservoir fluids provides valuable information regarding baffles and barriers to vertical and lateral fluid communication. The review presented here shows that gas chromatography mass spectrometry (GCMS) allows rapid, accurate, and economical characterization of the numerous geochemical compound classes that comprise reservoir fluids. In the Cretaceous McMurray formation of Alberta, compounds such as alkylnaphthalenes, alkylphenanthrenes, and alkyldibenzothiophenes vary in concentration corresponding to the level of biodegradation in a given reservoir section. Concentration profiles are interrupted and offset by baffles and barriers to fluid communication. Such information allows geoscientists and engineers to make informed decisions about well placement and maximize hydrocarbon recovery. It is possible to access these data through the analysis of legacy core samples by GCMS, as well as helping to show the extent of steam chamber formation. Prevailing economic conditions make it imperative that producers maximize recovery efficiency, and detailed knowledge of reservoir structure and hydrocarbon quality through the use of molecular geochemistry is an important part of working more effectively with the tools at hand.