A New Correction Method for Oil–Water Relative Permeability Curve on the Basis of Resistivity and Water Saturation Relationship

Oil–water relative permeability curve constitutes important basic data in reservoir engineering. Given the influence of dead volume on experimental apparatus, the actual oil–water relative permeability curve cannot be obtained when the unsteady-state method is adopted to measure oil–water relative permeability. In this paper, on the basis of the analysis of the influence of dead volume on oil–water relative permeability, we summarize the conventional methods used to overcome dead volume and then propose the use of relationship theory between resistivity and water saturation to calibrate the oil–water relative permeability curve. This method mainly aims at to measure the resistance values at both ends of the core by using a resistance-measuring instrument. Meantime, the Archie formula is used to calibrate the relational expression of core resistivity and water saturation based on the steady-state experimental method. Therefore, the core of the actual cumulative oil production and the average water saturation can be calculated, and then oil–water relative permeability can be accurately computed without the influence of dead volume. By comparing the oil displacement process of dead volume calculated through two different methods (probability subtraction and resistivity methods), the crude oil in dead volume is found to be displaced at the beginning of the displacement. The oil–water relative permeability curve corrected through resistivity method can eliminate the influence of dead volume and iterative error in calculation, and is consistent with the law of the actual development of oilfield, which has certain theoretical and practical application values.