Currently, a global attention has been paid to the development and exploitation of shallow depth heavy oil reservoirs. Such oilfields are rationally developed via a network of horizontal wells. However, the weakly cemented reservoir rock beds lead to the high sand production during well flow. Removing mechanical impurities is still challenging even with the application of sophisticated techniques and a variety of filters. In this study, we propose an analysis method for describing the removal of mechanical impurity particles from horizontal wells containing heavy oil. We employed a simulation model of typical well in OLGA program, and several calculations was made for different values of the flow rate. Moreover, deep sand samples were isolated from a well of Uchebny field to compare the real data with the estimated one. Calculations are used to estimate the quality of mechanical impurity removal for various diameters, and a relationship between the critical diameter and well flow rate is built.