Formulation Optimization And Numerical Simulation Of Profile Control And Flooding For Pu 125 Well Area

Pubei Oilfield put into development in 1979, had entered later stage of water flooding. Two problems were revealed:First, the remaining oil was highly dispersed, but there was still large space of tapping potential. Second, because of contradictions of planes, inter layers and interior layers, high permeability layers had many inefficient circulations, but thin and poor layers were poorly utilized. Profile control for the near wellbore area was not effective or had short period of validity. According to the situation of Pubei Oilfield, deep profile control and flooding technology was practicable. It could reduce the influence of contradictions of planes, inter layers and interior layers. It could expand swept volume of water flooding, and improve the development efficiency of Pubei Oilfield. Therefore, field experiments of deep profile control and flooding in Pu 125 well area had important practical significance.According to the principles of optimization, this paper selected a weak gel system of polymer and chromium as the agent of the field experiments. Main factors that affect its performance were studied, and formulation optimization was made. This system fitted the conditions of reservoir and fluid of Pu 125 well area well. According to the reservoir conditions, two kinds of polymers were used. The molecular weight of polymers should be 8 million and 14 to 16 million. The concentration should be 1000 to 1500 mg/L. The polymer to Cr3+ratio should be 20:1. And the concentration of the stabilizer should be 500 to 700mg/L. Because of the use of sewage water, efficient bactericide should be added to the system, and the concentration should be 150 mg/L. This system had good shearing resistance, good viscosity-elasticity and long-term stability.This gel system had high residual resistance factor, could play a good role in plugging the cores and the dominant channels such as fractures, and highly reduced the permeability of the cores. Parallel cores experiment and microscopic oil displacement experiment showed that this system had good flow steering capability, could expand the water flood swept volume and increase the oil recovery.Geological model of Pu 125 well area was made using Petrel software, and numerical simulation model was made using Eclipse software. The region’s reserves matching and water flood history matching achieved a good accuracy. The injection parameters were designed according to the reservoir characteristics, production and related test data of the well area, combined with the experience of past field experiments and research of numerical simulation. Slug size, injection concentration, amount of gel system, and injection pressure were designed. Numerical simulation results showed that after the use of deep profile control and flooding of nine injection wells in Pu 125 well area, oil production increased, water content ratio of the produced fluid decreased. Oil production of the well area was expected to increase by 2.85 x 104 tons, and oil recovery was increased by 2.40%. Oil production of the seven central wells was increased by 1.54 x 104 tons, and oil recovery was increased by 3.04%.