Thermal reconstruction of sedimentary basins - Applications and implications for O&G exploration
GeoLogin 3G aims to constrain the thermal histories of onshore and offshore basin systems for Oil & Gas exploration.
We produce a broad and detailed evolution in terms of temperature and timing and this in any basin.
For this purpose we 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 conventional approach and circles (2) the unconventional approach.
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 within or below the metastable temperature zones.
2) Sediments with Apatite and Zircon that have been fully reset. They can be considered as part of the "thermochronological" substratum and their thermal reconstruction is straightforward.
3) Beach sandstone, shales or carbonates do not host apatite minerals. A basic trick allows us to reconstruct their thermal history.
We can produce, compile, look for existing databases for you in order to constrain the:
Paleo-thermal history, or time of residence of basin fill series within the oil (160-60°C) and gas (200-160°C) temperature windows (OTW and GTW) whatever the lithology is (Fig. 2). Please note that these windows are dependant on the composition of the organic material.
Analyses are completed using outcrop and/or core/cuttings samples.
Rates of erosion in the orogen and sedimentation in the basin ( Fig. 1)
Date and quantify: 1) deformation, e.g. fault and fold propagation, fault gouges and differential exhumation, salt tectonics but also 2) missing or eroded sedimentary piles.
Illite crystallinity analyses to compare with paleo-thermal reconstructions
Additional geochemical and mineralogical analyses, e.g. Rock Eval and vitrinite reflectance
We are surprised that there is still a lack of knowledge in the thermal aspect of basin systems in the O&G industry because there aren’t many of parameters to generate oil and gas as temperature does. Unfortunately Academia preferred to concentrate on development when industry needs it since decades. The approach we developed add values to future operational and exploration studies in order to achieve scientific and economical advancements in the oil and gas industry.
Figure 2: Temperature-time models for an Aptian-Albian reservoir. 1, 2, 3, 4 are the four low-temperature thermochronometers with their metastable temperature zones (light grey, see 'methods') and Oil and Gas Temperature Windows, i.e. OTW (160-60°C) and GTW (200-160°C) respectively.
AFT (150 Ma) & ZFT (180 Ma): Apatite and Zircon Fission-Track analyses. AHe (18 Ma), ZHe (178 Ma): U-Th-Sm/He analyses on apatite and zircon respectively.