Abstract: Considering the current high proportion of low-yield and low-efficiency horizontal wells around Daqing Placanticline, research on the characteristics of residual oil distribution in horizontal well groups is urgently required. Thus, this study focuses on the flood pattern streamlines and pressure distribution characteristics of jointly developed horizontal and vertical wells. Through the application of the source-sink theory and the superposition principle for pressure, pressure field models with only vertical wells, only horizontal wells, only fracturing horizontal wells, and jointly developed vertical/horizontal wells were constructed. The Euler method was used to solve these models, where two, three, and four nodes formed the well network used in simulation to obtain the pressure field and streamline distribution. The research shows that the major trends of pressure fields and streamline distribution in horizontal wells when different network completion methods are applied were the same. When the wells were located at side wells, which are directly opposite to the horizontal wells, linear progression was easily formed between the wells and horizontal wells. When the wells were located at corner wells, which were thus not directly opposite the horizontal wells, linear progression could not be formed easily and resulted in a large area of low pressure. The distinct feature of fracturing horizontal wells is that the pressure gradient field of the outer crack is larger than that of the inner crack when the well is not directly opposite the horizontal wells. The accuracy of this study's results was further verified by comparison with the residual oil results of the well group numerical simulation. These results will help to fulfill the purpose of guiding the research and development adjustment of the residual oil distribution characteristics of the horizontal well group.

Key words: joint development of horizontal and vertical wells, pressure superposition principle, pressure field, streamline distribution