Described herein is an empirical model to estimate inflow performance relationship (IPR) of fishbone wells. A reservoir simulation model is formulated and initial values for a plurality of reservoir and fishbone well parameters are assigned. IPR curves are generated by simulating the formulated reservoir model for a predetermined number of iterations. Each simulation iteration has a unique value of bottom-hole flowing pressure. Sensitivity analysis is performed based on the generated IPR curves by sequentially changing the values of the plurality of fishbone well parameters. Further, regression analysis is performed based on the sensitivity analysis in order to determine an empirical model that estimates the IPR of the fishbone well. The empirical model is determined as a function of a number of multilateral branches of the fishbone well.