Bottomhole pressure is one of the important parameters that affect oil production capacity and the adjustment scheme of oil field. It is also the basis of dynamic analysis of oil and gas wells, and the production capacity of the well is controlled directly. However, due to the complexity of the formation conditions, there is not a systematic method to calculate the bottom hole flow pressure. Based on level conversion method, the fluid in the annular space of an oil sleeve is divided into three different flow patterns of gas column, oil and gas and oil gas water. The field test results show that the average relative error between the measured pressure value and the measured pressure value of the pumping well bottom hole pressure of the pressure gauge is 8.54%, which can meet the actual needs of the field.

Firstly, the molecular coil size of 4 kinds of polymers, whose molecular weight polymers is 8 million, 12 million, 16 million and 20 million respectively, was measured by the light blockage counter. Then pore cumulative distribution curve of field cores was measured by kerosene mass method. Finally the relationship curves between polymer molecular coil size and inaccessible pore volume of field cores were plotted. On the basis of this study, the water saturation value is assigned to the volume of the pore volume, and the polymer molecular weight with better compatibility with rock pores is optimized according to the relationship curve drawn. This method is based on the micro channel of underground rock. It has reasonable value and simple steps. And there are some guidances for the selection of the polymer in the oil field.