A comprehensive methodology for reservoir cut-off determination

Abstract The main objective of net pay determination, as an important step any reservoir study, is to exclude non-reservoir intervals so that better results are obtained from characterization, hydrocarbon in-place calculations, and dynamic flow simulation the reservoir. This study a comprehensive presentation most applicable methods available for highlighting their strengths, limitations, input data, presenting new procedure prepare determine pay, validate final results. These include conventional best-fit line quadrant in porosity–permeability cross-plot, Worthington method, rules thumb, cumulative column plot, production constraints. unlike previous ones, presents stepwise methodology reach correct answer considering both rock fluid properties. necessity definition discussed current first step. Determination net-to-gross ratio done by some cut-off values petrophysical properties such porosity, water saturation, shale volume. presented this flowchart zone uses different values. sequential systematic use all these gives consistent more reliable answer. key steps find porosity based on cross-plot pre-defined limiting value permeability then volume saturation cut-offs using cross-plots versus porosity. To take into account effect, mobility used starting point instead permeability. Cumulative plots sensitivity tool what percentage hydrocarbons will be discarded value. Finally, determined should validated logging wireline formation tests. proposed was applied real field its pay. Porosity were calculated 2% 55%, respectively, due clean nature reservoir, not necessary. Simultaneous application 6.3% example.