AAPG Annual Convention and Exhibition

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The Dual Role of Heavy Compounds in Conventional and Unconventional Petroleum Systems


Non-hydrocarbon heavy compounds, particularly asphaltenes, can be problematic in conventional reservoirs. They can obstruct the porosity and the permeability in the near-wellbore, as well as clog production tubing or above ground flow-lines and facilities. Prevention or remediation of asphaltene deposition adds huge costs to oilfield development. Asphaltenes are also found in source rock. They are a part of the naturally occurring continuum of compounds that result as organic matter is transformed into oil and gas. Interestingly, these high molecular weights compounds are kerogen moieties and can extend the amount of time that a source rock actively generates hydrocarbons. Also, there is a compelling correlation between source rock age and the amount of asphaltene created. The occurrence of asphaltene is related to the kerogen type and shows an orderly variation through geological time. This fact can be used in our screening process as we select which source rocks to target for unconventional drilling and production. While referring to some well-known US unconventional oil /shale gas systems we will discuss the role of heavy compounds at the oil window and their importance in the later stage of hydrocarbon generation for an unconventional play.