Methods, systems, and computer-readable media for assessing porosity and water saturation cutoff values for hydrocarbon volume estimation are described. The techniques can include determining a plurality of water saturation and porosity value pairs for locations regularly-spaced along at least one borehole. The techniques can further include plotting the plurality of water saturation and porosity value pairs on a graph and representing a plurality of percentiles of the estimated maximal hydrocarbon volume on the graph. The techniques can also include causing the graph to be displayed to a user, such that the user can visually observe a combined sensitivity to porosity and water saturation cutoffs values. The user can take various actions based on the display.