Abstract: Based on a systematic examination of commonly used optimization methods from the point of view of log interpretation and computer processing, this paper suggests that the optimization method combined with BFGS variable metrice algorithm with parabolic interpolation as its linear search could be used to evaluate shaly sand resevoir according to the Dual Water model. An optimization log interpretation program has been developed and the well logging data of a shaly sand formation in Sheng-Li oilfield were processed. Several problems, such as logging response equations and choice of interpretation parameters, are examined according to the special feature of the oilfield. All results showed that the petrophysical data and mineral components obtained were very consistent with the results of core analysis and Schlumberger GLOBAL program processing. It has been proved that the use of optimization method and Dual Water model to evaluate shaly sand reservoir has not only a theoretical significance but also a better practical value.