Large scale application of surfactant displacement distance polymer flooding at home and abroad

2020-08-17 16:53:01

In the past two years, the Ministry of science and technology of the people's Republic of China, two major oil companies, PetroChina and Sinopec have organized a series of research projects on surfactant compounding, and organized large oil fields, scientific research institutes and universities to carry out a series of research projects, and achieved some basic research results. In the surfactant flooding system of Zhongyuan Oilfield, Changqing Oilfield, Dagang Oilfield and Yanchang oilfield, several low permeability reservoirs have been selected for field test, and the effect of EOR is obvious. In Zhongyuan Oilfield, the displacement efficiency of composite surfactant in formation water is 7.68% higher than that of petroleum sulfonate. Shengli Oilfield developed a low-cost composite surfactant for oil displacement in Zhuangxi area with high temperature and low permeability. The exploratory application test of the agent was carried out in No.5 zhuangzang 50 well group in 2006. As of May 2007, the oil production of 6 wells in this well group increased by 1656 tons.   

The characteristics of low permeability reservoirs are as follows:

1) There are many faults and complex structures, small oil-bearing area, many layers, large thickness, many faults and complex structure. Due to many faults and compactness, reservoirs are often divided into isolated small fault block oilfields, with relatively small oil-bearing area, but the thickness of multiple layers varies little, from several meters to tens of meters or even hundreds of meters.     

2) The reservoir physical properties change greatly, with small pores, large specific surface area and low permeability. The average throat diameter of small pores and micro micro micro throats in low permeability reservoirs is between 26 and 43 μ m, the median pore throat radius is 0.1-2.0m, and the specific surface area is 2-20m2/g. The main reason of the low permeability reservoir is that the reservoir has a series of low permeability. A kind of

3) The percolation characteristics do not follow Darcy's law. Because of small pores, large specific surface area and reservoir boundary thickness, Jamin effect and surface molecular force are strong, the percolation law of low permeability reservoirs does not obey Darcy's law, and the non Darcy flow characteristics are obvious. The lower the permeability, the greater the threshold pressure gradient.       

4) The elastic energy of low permeability reservoir is low because of poor connectivity and low flow resistance. Generally, the edge and bottom water are not active and the elastic energy is very small. In addition to a small number of abnormally high pressure reservoirs, the recovery in elastic stage is only 1% to 3%. A kind of

However, up to now, surfactant flooding at home and abroad still has a long way to go from the stage of large-scale application of polymer flooding, mainly due to the following reasons: high cost and low benefit; second, it is necessary to select suitable surfactant according to different reservoir characteristics, which limits the large-scale production and Application of surfactant. Therefore, research and development of surfactant flooding system with high performance and low cost is the inevitable trend of the development of petroleum industry.