Use of GPR to image beachridges, geometric analogue of pre-salt coquina deposits
Georadar; Beachridges; Reservoir Geometric Analog.
The geometric characterization of coastal ridges deposits prompts the interest of the oil industry as they are recognized as important pre-salt carbonate reservoirs, interpreted as prograding lacustrine beach systems. The objective of this work is to apply the Georadar method (Ground Penetrating Radar - GPR) to image siliciclastic beachridges deposits in order to better understand their geometries and associated deposits. The siliciclastic beachrodges were chosen because they better respond to imaging with the GPR method, in terms of resolution and depth, compared to the homonymous carbonate deposits. It is expected that the geometric information obtained can help to overcome the lack of data between the seismic scale and that of data from wells from carbonate reservoirs of pre-salt coastal coquinas. Based on the orthophotomosaic, produced for the study area, on the potiguar east coast, a geophysical acquisition plan and a geomorphological zoning were carried out. The GPR survey was execute with a 200 MHz antenna, in the common offset configuration in continuous mode, forming an irregular mesh with 6 ENE-WSW lines (300 to 350 m) and 3 NNW-SSE lines (350 m), with an approximate spacing of 70 m and total length of 3,135 km. From the terminations of the reflections and applying advanced processing (use of “attributes”), it was possible to identify and highlight the geometries of the beachridges deposits and the water table. The interpretation of the GPR lines will also be finalized and a 2.5 D virtual model will be prepared that includes the backshore, foreshore and shoreface deposits. In addition to washover deposits and those generated by longshore currents, preliminarily interpreted.