Abstract

The Lukeqin Triassic reservoir in Xinjiang, China, is a heavy oil reservoir with high temperature and high salinity. The formation conditions are harsh. With the deepening of oilfield development, the reservoir enters into a high water cut period and faces the problem of stable oil and water control in the middle and late stage of development. In addition, the heavy oil reservoir has complex characteristics, such as deep, thin, thick and so on, so it can not be converted to conventional thermal recovery mode. Therefore, a solution to the reservoir conditions is urgently needed. In order to improve the mobility ratio of water drive, a new type of high temperature resistance and high salinity polymer SWP322 has been developed. In this study, the compatibility, viscosity, temperature resistance, salt resistance and shear resistance of the polymer in Lukeqin reservoir were evaluated and compared with that of HPAM. Finally, the formation conditions of Lukeqin reservoir are simulated to test the percolation and oil displacement ability of the new polymer SWP322 under the conditions of high temperature and high salinity. Experiments show that the polymer has a temperature resistance of 100°C and a salinity resistance level of 2.0×105 mg/L. The experimental results show that the polymer SWP322 has a lower dissolution rate at room temperature than HPAM, but its temperature resistance, salt resistance, shear resistance, and temperature resistance are far better than those of HPAM. With the increase of temperature and salinity, the apparent viscosity of HPAM decreased rapidly, while SWP322 was almost independent of temperature and salinity, and the viscosity retention rate was more than 99%; at the same time, the viscosity retention rate of SWP322 after core shearing also reached 98.6%, which proves that SWP322 is superior to HPAM in its resistance to temperature and salt, and excellent shear resistance also helps to maintain the viscoelasticity of the polymer in the formation. Increase oil displacement efficiency. In terms of seepage capacity, the flow resistance of SWP322 is much better than that of HPAM, and the resistance coefficient and residual resistance coefficient are all more than 5 times that of HPAM; in the process of simulated oil displacement, the displacement efficiency of water flooding is 30.43%, while the flooding efficiency of first polymer flooding and subsequent water flooding is 16.6% higher than that of water flooding; the oil displacement efficiency of double-pipe polymer flooding is 13.19% higher than that of water flooding; the oil displacement efficiency of single tube and double tube flooding system is 16.1% and 23.2% higher than that of water flooding, respectively.

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