WHY AFTA^® ?

Since the timing of maximum paleotemperatures within sequences containing prospective hydrocarbon source rocks generally coincides with maximum hydrocarbon generation, good control on the timing is a critical factor in assessing regional hydrocarbon prospectivity. Areas where the main phase of hydrocarbon generation occurred after structures were formed will clearly be more prospective than areas where structures post-date hydrocarbon generation.

AFTA thermal history reconstructions provide direct determination of the timing (as well as the magnitude) of maximum paleotemperatures. When combined with conventional maturity indicators, particularly vitrinite reflectance (VR), this approach allows identification and characterisation of the major episodes of heating and cooling which have affected a sedimentary sequence. Specifically, the Geotrack methodology of Thermal History Reconstruction provides the following information:

• magnitude of maximum paleotemperatures in individual samples
• timing of cooling from maximum paleotemperatures
• the style of cooling from maximum paleotemperatures (fast; slow)
• characterisation of mechanisms of heating and cooling
• measurement of paleogeothermal gradients and determination of paleo-heat flow
• determination of section removed by uplift and erosion (where appropriate)
• reconstructed thermal and burial/uplift histories based on these parameters

Using this information the thermal history of likely hydrocarbon source rocks can be reconstructed with confidence, on the basis of measured parameters, rather than relying on modelled results which often have little rigorous basis. The resulting improvements in assessment of hydrocarbon prospectivity is clearly beneficial in reducing exploration risk.

The technical basis of Apatite Fission Track Analysis - details.