Study on The Timing of Infilling Adjustment of Low-abundance P Reservoirs

Abstract Low-abundance P reservoir has been developed by using vertical-horizontal joint well pattern in some areas. To address declining production efficiency, the oilfield initiated vertical well density optimization starting in 2000. Building on this experience, a novel approach combining vertical and horizontal well patterns was introduced in 2018 to enhance reservoir recovery in joint development blocks. The field implementation and effect show that the infill timing significantly impacts the production. Therefore, we need to implement well density optimization within the appropriate water cut range to obtain higher initial production and better economic benefits. The study analyze the implementation effect of block infill wells over the years. The optimal infill timing was established through target production analysis, dynamic difference evaluation, water saturation monitoring, and numerical simulation in vertical well area and horizontal well area. Key findings reveal: ① Vertical well patterns achieve optimal infill adjustment at 60-80% water cut.② Horizontal well patterns show best performance when adjusted at 60-70% water cut. Infill timing exerts maximum influence on initial production of central infill wells. In high water-cut stages, reducing central well density enhances overall development effectiveness. These findings provide operational guidance for well density optimization in similar low-abundance reservoirs.