The diesel generators are usually used for supplying the electrical demand of the semi-submersible oil drilling rigs. The specific fuel consumption (SFC) of each diesel engine changes nonlinearly with respect to its power product.Hence, this paper presents an economic fuel dispatch model for diesel engines powered oil rig platforms using the cubic spline interpolation curve fitting of the SFC-power non-linear dependence. Moreover, the total fuel consumption of the diesel generators significantly reduces by shifting a partial part of the electricity demand of the offshore drilling rigs from on-peak time intervals to off-peak periods. In addition, battery energy storage contributes to the load curve smoothing strategy. A mixed-integer non-linear programming problem is developed under generalized algebraic mathematical modeling system to find the optimum fuel consumption and power generation schedules of the diesel producers, the value of demand increase/decrease, and the charge/discharge pattern of the battery at each operating time interval. A benchmark oil rig with