Hydrocarbons

GRDC uses a nine component hydrocarbon analysis including the saturated hydrocarbons Methane through Pentane, the unsaturated hydrocarbons Ethene and Propene, and the isoalkanes, isobutane and isopentane. The analysis is preformed using standard gas chromotography.

Hydrocarbons seep naturally from the reservoir to the surface and are detected in minute amounts within the soil matrix, either as pore gas or as lightly held molecules on the soil grain surface. GRDC uses a bulk soil sample for analysis so that any free or loosely held hydrocarbons present will be captured in the sample "headspace" upon sample preparation. Tightly held "occluded" hydrocarbons are not removed in the sampling or preparation process and are not available for analysis. Therefore, the signature obtained will be "apical" or coincident with the hydrocarbons at depth instead of a "halo"configuration where the anomalies would be associated with the periphery of the reservoir at depth.

GRDC uses a three STEP (Surface Techniques for the Exploration of Petroleum) exploration program when running surveys. The primary role of surface geochemical exploration is anomaly detection. Is a statistically valid signature present? A reconnaissance survey is used for this purpose and can be either a sample traverse or loose sample grid. Once an anomaly is located a detailed survey is run to delineate aerial extent and verify the source of the hydrocarbons as being either biogenic or thermogenic.  This step is accomplished through high density sampling and multivariate data processing procedures. Characterization of the anomaly is the final step. Comparison of compositional ratios with known analogs allows estimates of reservoir age, maturity, and fluids to be made. This can be very diagnostic when integrated with existing geology and geophysics.

Great strides have been made in surface geochemical surveying. Exploration now spans any number of techniques or combination of methods. GRDC always recommends a multi-parameter approach and provides several indirect methods in conjunction with the hydrocarbon surveys FREE of charge, which allows for a complete evaluation of a prospect.