fine

just use any correlations in the laterature as corey
kr as function of saturation and saturation exponent which will give the curvature of kr relations


for a starting point assume your endpoints based on your wells performance if good producers kro = 0.8 krw = 0.1 something like
if the correlation donot give same end point for oil just put them equal and go ahead no issue my friend life is simple

after you'll get you core data you'll have higher confidence


hope it is helping
hope it is helping