Influence Of Heavy Oil Ring On The Oil/Water Movement

The water cut in the middle and late stage of field development is usually high. Therefore controlling water is one of the most important measures to improve the oil recovery factor in middle and late development stage. The oil and water movement often becomes complex at this stage. The heavy oil ring in G6 block of GJ oil field, makes the oil and water movement more complex. The study of oil and water movement under the influence of heavy oil ring will provide guidance for adjustment of oilfield development plan.Heavy oil is a kind of special fluid, which exhibits the Bingham fluid characteristic, with a threshold pressure gradient, therefore its flow behavior cannot be described by the Darcy’s Law. Only the modified Darcy’s law can be used to describe the heavy oil movement. On the basis of conventional black oil model, the mathematical model considering threshold pressure gradient is built, which is then discretized using finite difference method. The algebraic equations are solved numerically to form the reservoir simulator which considers the influence of threshold pressure gradient. Material balance test and functional test are performed on the simulator. It is then used to analyze the performance of the reservoir under various oil viscosity, distribution form, and injection manner.Study show that the existence of heavy oil ring in the reservoir accelerates the rise in water cut, and the oil rate decline, therefore influence the development effect of the oilfield. Due to the presence of the heavy oil ring, more energy is exhausted to overcome the threshold pressure gradient, resulting in waster of formation energy. The influence is more obvious with higher oil viscosity.