1. A method of operating a computer system to determine an empirical model to estimate inflow performance relationship (IPR) of a fishbone well, the method comprising: formulating a reservoir simulation model that includes the fishbone well and assigning initial values for a plurality of reservoir and fishbone well parameters; generating, by a processing circuit, IPR curves by simulating the formulated reservoir model for a predetermined number of iterations, wherein each iteration has a unique value of bottom-hole flowing pressure; performing, by the processing circuit, sensitivity analysis based on the generated IPR curves by sequentially changing the values of the plurality of fishbone well parameters; and performing, by the processing circuit, regression analysis based on the sensitivity analysis to determine an empirical model that estimates the IPR of the fishbone well, wherein the empirical model is determined as a function of a number of multilateral branches of the fishbone well; deploying a fishbone well based on the empirical model.