Method and system for processing seismic images to obtain a reference RGT surface of a geological formation

A method implemented by a computer for processing a seismic image obtained from seismic measurements performed on a geological formation, said method comprising:

• determining a relative geological time (RGT) image based on the seismic image;
• obtaining setpoints for the RGT image, said setpoints representing constraints to be satisfied by a reference RGT surface to be determined;
• retrieving an RGT surface of the RGT image for each of the setpoints, wherein each point of an RGT surface is defined by a vertical position and at least one horizontal position;
• and
• determining the reference RGT surface by combining the RGT surfaces determined for the setpoints, wherein a vertical position of a respective point of the reference RGT surface is obtained by combining the vertical positions of the points of the RGT surfaces having a same at least one horizontal position as the respective point of the reference RGT surface;
• wherein said combining of the vertical positions uses weighting coefficients;
• and
• wherein a value of a weighting coefficient used for the vertical position of an RGT surface decreases with a distance increasing between the at least one horizontal position of the respective point of the reference RGT surface and the at least one horizontal position of the setpoint associated with a respective RGT surface.