A Study On Laboratory Experiment And Numerical Simulation Of Nano-micron Polymer Flooding For Low-permeable Reservoir

Low-Permeability Reservoir has become the main battlefield of China's petroleum domain, Cumulative proved oil reserves in place of low-permeability reservoir has reached 14.1 billion tons by the end of 2008 in China, accounting for 49.2% of the total petroleum geological reserves in China. The geologic reserves of low permeability reservoir cover an average of more than 70% of the newly-added petroleum reserves. In 2008, oil reserves of low-permeability reservoirs is 71 million, and covers 37.6% of total reserves in China. At present, Early exploited low permeability reservoirs of Daqing Oilfield have come into high water cut stage gradually, production speed is low in the reservoir and it is difficult in production, which brings great pressure for the oilfield production and power consumption. However, mature polymer technology has high injection cost for low-permeability reservoir, therefore, laboratory experiment and numerical simulation of nano-micron polymer flooding for low permeability reservoir is studied, and new techniques for raising tertiary recovery ratio is explored for the low permeability reservoirs of high water cut stage.The first, according to the reservoir physical properties of Longhupao oilfield, four nano-micro polymer samples are preliminarily selected, and based on the grain size variation, morphological changes, dilation dimension, the four nano-micro polymer samples. Some characterization methods such as particle analyzer and electron microscope were used to optimally select oil displacement profile control agent that is suitable for the oilfield.The second, applying simulated sewage water to prepare the nano-micro polymer solution and making laboratory plugging experiment, which shows that nano-micro polymer can be injected successfully and can plug high permeability reservoir after expansion, in certain pressure making a breakthrough and realizing gradual profile correction. The results of displacement experiment indicated that nano-micro polymer can effectively produce crude oil of low-permeability reservoirs, recovery efficiency rose by more than 17%, more bigger difference of the permeability level difference, the more improved obviously of the recovery efficiency.The third, based on the seepage characteristic of nano-micro polymer displacing oil, establishing mathe-matical model of 3-D,3-phase,3-components nano-micro polymer profile control and flooding. With consideration of convective diffusion and seepage characteristic of profile control and flooding, the numerical solution (implicit pressure, explicit saturation, and implicit concentration) in the model is given, and a corresponding numerical software is compiled. Through research on numerical simulation of water driving and nano-micro polymer profile control and flooding for field test area of nano-micro polymer displacing oil in Longhupao oilfield, the injection parameters are improved, and the purpose of reducing water, increasing oil and raising recovery is achieved after carrying out. These agreed with the predicting indexes of numerical simulation basically.