Isopachous map bulk volume determination

To find the area enclosed by contours, you decided to create  grids by 0.5×0.5 cm and counted the number of grids to find the area enclosed by each contour line. Later, you applied the following methods to find out the bulk volume and compare the results. 

– Area vs. thickness graph 

– Pyramidal and trapezoidal equations

Draw the cross-sections of your reservoir indicated by red and green lines on your map

Based on the provided data, what are the depths of formation top, GOC and WOC in m BSL (below-sea level).