Abstract: The paper continued with the previous study and collected and introduced 10 relationships on water dis- placement curves, adding the total to 50. Among these 10 proposed relationships, for Ordinary water-flooding oilfield, No.45 water displacement curve is more valuable,with its f_w-R* relation curve being concave—shaped, and it is more convenient and easier to acquire the solution of the curve parameters. No.41, 47,48 and No.50 curves are all generalized curves among which No.41 (namely WANG Jun-kui water, displacement curve) has more practical value while No.50 has a certain applicable value. No.47 curve is more complicated to solve for the parameters, while No.48 has a very rare water-displacement characteristics, and is of little practical value.

Key words: Water displacement, Displacement curve, water cut, recoverable reserve, recovery percent, application