We continue our Lebanon neoBASIN project series, this time, taking a look at some large, basement-driven structural highs that have been identified in the Triassic and Paleozoic intervals in the survey area.
Our highly constrained, multi-measurement methodology for developing these types of 2-D cross-sectional models is covered elsewhere (you might review our MMI 101 narrated slideshow (click here) or read our 2014 Marcellus case study from URTeC (click here) if you want a richer refresher.
In a nutshell, we develop these models by evaluating the response of actual acquired multi-physics geo-data (in this case, gravity, magnetic and EM resistivity measurements), making certain assumptions about the thickness and physical properties (density, magnetic susceptibility, and resistivity) of key intervals, and iterating until the model converges with all acquired data and with any other constraints we might have, such as outcrop, well or seismic (which we didn’t have in this case) information.
In the image above, you’ll note that we determined that there were some topographic highs in the basement (the red interval) and that these basement-involved features affected the younger intervals deposited above them – in particular, the Paleozoic (green) and Triassic (purple) horizons. Faults were mapped with other datasets, in particular magnetic but also EM. To learn more about the importance of basement topography, faulting and composition in hydrocarbon exploration, read our article in E&P.
These fault-bounded structural highs were seen in other parts of the survey area as well. In many cases, interpretations of the acquired Grav-Mag and EM datasets suggest that these features continue ‘into and out of the page’, thereby creating elongated anticlinal structures that could be intriguing exploration targets.
Now if only NEOS had some seismic imaging capabilities to further delineate the vertical and lateral extent of these anticlinal structures (???), but I digress…
In Part 1 of this series, we described the presence of oil seeps on the surface, in many cases, concentrated along faults and juxtaposed stratigraphic intervals outcropping on the surface. If the seeps were generated from Paleozoic or Triassic source rocks, what are the odds that some of the hydrocarbons became trapped in structures like these as they migrated towards the surface?
In an upcoming post, we’ll share some intra-horizon resistivity anomalies that indicate an increase in interval resistivity in structures similar to the ones highlighted here as one moves up the geologic column.