The Paraná Basin is located in an area of attractive economic context due to the proximity to a region with high energy demand in Brazil. The possibility of gas production from the Paraná Basin is an extremely important issue since the consumers are currently relying on gas imported from Bolivia into Brazil. However, there is a lack of land geophysical data due to the large size of the basin and the thick cover of the volcanic Serra Geral Fm. We present the first large-scale 3D land geophysical survey carried out in the central portion of the basin with the objective of uncovering its gas potential. Proof of generation conditions was achieved through analysis of drilled wells. The magnetotelluric (MT) method proved to be an excellent tool, imaging the sediments, basement and structures below the Serra Geral. However, most MT projects carried out in the basin were 2D transects for academic or reconnaissance purposes. The resistivity model obtained from the MT data detailed the volcanic cover and below, imaging dikes and sills, revealing a petroleum system similar to other basins in Brazil that are actively producing gas producing.
The Paraná Basin (figure 1) is a large sedimentary basin that occupies an area of approximately 1.5 million km2 in east-central South America. The Paraná Basin is an intracratonic basin and has an oval shape with a major N-S axis. Its contour is defined by erosional boundaries related to the continent's Meso-Cenozoic geotectonic history (Milani et al. 2007). The east of the basin was shaped by erosion as a function of crustal uplift associated with the South Atlantic rift, with an estimated sediment removal of 2,500 meters (Zanotto, 1993). The western portion of the basin is guided by a flexural bulge related to lithospheric overload caused by the Andean orogenic belt (Shiraiwa, 1994 apud Milani et al., 2007).
Large scale MT surveys have been conducted in different portions of the Paraná Basin and the method proved very efficient to image below the thick volcanic cover of the Serra Geral Fm (Philipp et al. 2014, Palshin, 2017, de Lugão et al. 2020). The 3D MT project presented here is the first of its kind in the basin. The project was designed to detail geology and comprises 462 stations, spaced every 2 km in an area of 50 km by 50 km, generally located in the central portion of the basin (figure 1).