High-resolution seismic investigation in phosphate mining

Charbaoui A.^(1*), Jaffal M.^(1,2), Kchikach A.^(1,2), Eljabbar B.⁽¹⁾, Bodinier J,L.^(1,3), Rochdane S.⁽¹⁾, Khadiri O.⁽⁴⁾, Jourani E.⁽⁴⁾

 

(1) Mohammed VI Polytechnic University, Geology and Sustainable Mining (GSM), Benguerir, Morocco

(2) Cadi Ayyad University, Georessources, Geoenvironment & Civil Engineering Laboratory, Marrakech, Morocco

(3) University of Montpellier & CNRS, Geosciences Montpellier, Montpellier, France.

(4) OCP Group, Casablanca, Morocco

*Email: anas.charbaoui@um6p.ma

 

Abstract

Seismic reflection is extensively used in petroleum exploration because it is recognized as an excellent tool of geological imaging, especially for sedimentary basins. In recent years, a variant of this method, namely the high-resolution seismic reflection (HRS) has experienced a rapid development due its implementation in many shallow geophysical investigations including studies in geotechnics, hydrogeology, structural geology, seismic hazard estimation, etc. This method can provide continuous coverage of the underground in two-dimensional 2-D, as well as in three-dimensional 3-D spaces. The HRS method has a lot of successful applications in shallow underground prospecting for various purposes (Tallini et al. 2020, Ahokangas et al. 2020).

The present project is concerned with the study of the Bahira basin, which hosts some of the most important phosphate deposits of Morocco. Its main objective is to provide a detailed seismic imaging of the phosphatic series, particularly in the area where it is hidden by a plio-quaternary cover. The Bahira phosphatic series is made of a Maastrichtian to Ypresian regular intercalation of phosphate beds and sterile layers.

The studies planned in order to reach this objective include first and foremost, the knowledge of the different terms of phosphatic series through (i) the analysis the available boreholes data, so as to gather information about the thickness of the layers, their lithological lateral change, etc., and (ii) the measurement of the rock properties necessary for the seismic modelling. The next step is to carry out numerical simulations that would help establish the expected seismic response of the phosphatic series. This also would aid to determine the appropriate parameters of the subsequent data acquisition. The third step is to perform HRS survey on the areas of interest. This will includes 2D surface seismic profiling and borehole vertical profiling (VSP). The projected studies also include performing measurements of Electrical Resistivity Tomography along the same survey profiles as the HRS. This would help realize a joint inversion of the two type of data and contribute to a better understanding the phosphatic series deep structure.

 

References:

[1] Tallini M., Spadi M., Cosentino D., Nocentini M., Cavuoto G., Di Fiore V., 2020. High-resolution seismic reflection exploration for evaluating the seismic hazard in a Plio-Quaternary intermontane basin (L'Aquila downtown, central Italy). Quaternary Iternational (In press)

[2] Ahokangas E., Mäkinen J., Artimo A., Pasanen A., Vanhala H., 2020. Reflection method with landstreamer in SW Finland, Journal of Applied Geophysics 177, 104014

Keywords: Phosphatic series, high-resolution seismic imaging, numerical simulations, Joint inversion, Bahira basin, Morocco.