中深层稠油油藏蒸汽-氮气复合吞吐技术

Nitrogen Assisted Steam Stimulation Technology for Mid-Deep Heavy Oil Reservoirs

针对中深层稠油油藏地层压力高、注蒸汽过程中热损失大、蒸汽腔扩展范围小、注蒸汽开发效果差等特点,提出了蒸汽-氮气复合吞吐技术。针对渤海某中深层稠油油藏,通过实验和油藏数值模拟,深入研究蒸汽-氮气复合吞吐加热降黏、气体溶解降黏、重力驱替作用、增压作用、扩大加热腔作用、改变稠油流动形态和底水油藏注氮气的控水作用等开采机理,优化气水比、注汽量和注入方式等关键注入参数。数值模拟结果表明,注入温度为350℃时,最优气水比为50;对于厚度为10 m的油藏,水平井注汽强度为10～15 m^3/m.

Due to the problems encountered in middeep heavy oil reservoirs such as high formation pressure, large heat loss during steam injection, small expansion of steam chamber and poor steam injection effect and so on, nitrogen assisted steam stimulation technology is presented, which is an improved steam stimulation technology. In this paper, experiments and numerical simulations were conducted to research the mechanism of nitrogen assisted steam stimulation and to optimize the injection parameters for the target reservoir in Bohai oilfield. Production mechanisms of nitrogen assisted steam stimulation including viscosity reduction by heating, viscosity reduction by gas solution, gravity displacement, pressurizing, steam chamber expanding, flow behavior changing and water controlling during nitrogen injection into the reservoirs with bottom water are researched, and the key injection parameters such as gas/water ratio, steam injection volume and injection mode are optimized. The numerical simulation results show that when the injection temperature is 350 ℃, the optimum gas/water ratio is 50;the steam injection strength in horizontal wells is 10~15 m^3/m for the reservoirs with the thickness of 10 m.