TruVert 2-D provides a sophisticated calculation procedure to determine true vertical thickness (TVT) and net pay in deviated wellbores that penetrate dipping reservoirs. While the computation procedures are relatively simple, manual TVT calculations can be very time consuming and often confusing. With TruVert 2-D, the user enters measured-depth log data, either measured or subsea contact depths and standard directional survey data for rapid, accurate calculation results. TruVert 2-D enables the advanced user to emulate heterogeneous reservoir stratigraphy, providing net pay calculations by phase. As a bonus, TruVert 2-D incorporates Excel's versatile graphics-handling capabilities to provide the energy professional with printer-friendly, hard-copy output of individual reservoir geometry.