Research on Water Drive Pattern and Water Injection Strategy Optimization in Interlayer Development Area of Porous Carbonate Reservoirs

Abstract

Taking the MC-11 layer of Iraqi B Oilfield as an example, the seepage law in the process of water injection development is analyzed. Due to the thin reservoir thickness and the certain vertical seepage capacity of the interlayer, a large amount of injected water will flow into the top layer with relative high permeability. Through the study of numerical simulation, the effects of different injection mechanisms and interlayer physical properties on water flooding performances are characterized. The research results show that, (1) In order to prevent excessive water channeling in the oil producer, ensure the injection volume and improve the water drive efficiency, the injection layer section should be designed as II and III, which also remains some space for later development adjustment. (2) The differential pressure of water injection has an obvious impact on the development effect. Large differential pressure may cause early water breakthrough. When the differential pressure is moderate, the water drive sweep efficiency becomes relatively high, and the water cut of the oil producer rises more slowly, which leads to a better development effect. (3) Interlayer physical properties and longitudinal seepage capacity could significantly influence the water injection process. In the later development stage, a refined reservoir characterization should be carried out specifically for interlayer development areas, and differential injection mechanisms need to be adopted for areas with different interlayer properties to optimize regional water injection effect. (4) The optimization suggestions put forward in this paper can be directly applied to the actual water injection work of the B Oilfield, which has strong practicability and good guiding significance for development of similar oilfields.