--> Focusing Petroleum Exploration With Regional Geochemical Surveys

2014 Rocky Mountain Section AAPG Annual Meeting

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Focusing Petroleum Exploration With Regional Geochemical Surveys


A regional onshore geochemical exploration survey was carried out over the Yukon Flats and Nenana basins in east-central Alaska. The objectives of the survey were to focus exploration within a 2,100 square mile area and demonstrate the existence of liquid hydrocarbons in these supposed “gas-prone” basins. Lake bottom sediments were chosen as the preferred sample medium for the survey because the lakes are thought to be thermal windows through permafrost, they can be collected rapidly with helicopter support, and their effectiveness for detecting oil and gas fields was demonstrated in a previous study over the Tuk oil and gas fields in the Mackenzie Delta of northern Canada. The lake sediment samples were analyzed for headspace, saturated and unsaturated C1 to C7 hydrocarbons and also for traces of crude oil using Synchronous Scanned Fluorescence. The regional lake sediment geochemical survey over parts of the Yukon Flats and Nenana basins was effective in that liquid hydrocarbons were detected and the initial 2,100 square mile survey area was reduced to about 500 square miles of prospective ground based on the location of oil and wet gas microseeps. The location of a subsequent 40 square mile 3D seismic survey was guided by the results of the geochemical survey. Regional lake sediment geochemical exploration surveys are a cost-effective tool for demonstrating the existence of liquid-based petroleum systems in remote untested basins. The surveys also help focus more cost-prohibitive geophysical surveys and drilling.