Development and Practical Application of Pressure-Drive Water Injection String

Abstract

To address the challenge of "difficulty in water injection and oil production" in low-permeability reservoirs, Shengli Oilfield has developed three pressure-drive water injection development modes--"advanced pressure drive, three-dimensional pressure drive, and differential pressure drive" through continuous research, practice, and iterative upgrades. As a key carrier for technical implementation, the pressure-drive water injection string has formed a supporting model dominated by "multi-cycle zonal pressure-drive string and integrated pressure-drive water injection string". The technical indicators are: applicable casing size 4½in-7in; working pressure difference ≤50MPa; working temperature ≤150℃. By the end of 2023, a total of 107 well applications have been implemented with a sealing efficiency of 92.7%. Among them, the multi-cycle zonal pressure-drive string has been applied in 62 wells, with a maximum water injection pressure of 47MPa, a maximum formation temperature of 150℃, and a maximum injection rate of 1800m³/d. The integrated pressure-drive water injection string has been applied in 45 wells, with a maximum water injection pressure of 49MPa, a maximum formation temperature of 148℃, and a maximum injection rate of 2800m³/d.