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Thermal reconstruction of sedimentary basins - Applications and implications for O&G exploration

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GeoLogin 3G aims to constrain the thermal histories of onshore and offshore basin systems for Oil & Gas exploration.

 

I can produce a broad and detailed  evolution in terms of temperature and timing and this in any basin.

 

For this purpose I developed an  approach using different analyses in isotope geochemistry + Petrology and observations geology (Fig. 1).

Figure 1 : Application of low-Temperature thermochronology and implications for reconstructing the thermal history of O&G rich sedimentary basins. Four thermochronomters are used : (U-Th-Sm)/He and Fission-Track on apatite and zircon minerals : AHe, ZHe, AFT & ZFT. Circles (1) indicate the 'direct' or conventional approach and circles (3) the 'indirect or unconventional approach whereas circle (2) is targeting fault dating. Additional U-Pb and Raman Spectroscopy are also proposed.

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There are two ways to tackle the past thermal history in orogen-basin settings, the direct and indirect approaches (Fig. 1):

 

  • The first one aims to 'directly' constrain the thermal history of the orogen on bedrocks from the orogen and/or substratum of the basin. This allows an immediate inspection of thermal history for the first 15-10 kilometres of the crust.

 

  • ‘Indirect’ or 'detrital' thermochronology traces cooling records that are no longer present in the orogen since erosion has removed the record of earlier stages. This approach is not detailed here because it has no interest for O&G prospect but indicate that burial/heating was not sufficient to reset one or more thermochronometers. See Ruiz et al. (2004 & 2006) for further reading.

Sediments

 

Sediments, in terms of thermochronology can be divided in 3 groups:

 

1) Sediments with Apatite & Zircon that yield a thermochronological age older than the stratigraphic age. This suggests that burial/heating has not been sufficient to "reset", i.e. put the clock back to 0 Ma. The dated sedimentary remained at temperature below the metastable temperature zones.

 

2) Sediments with Apatite and Zircon that have been fully reset. They can be considered as a "thermochronological" substratum and their thermal reconstruction is straightforward.

 

3) Beach sandstone, shales or carbonates do not host apatite minerals. A trick allows me to reconstruct their thermal history.

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