渤海稠油S油田氮气吞吐提高采收率影响因素研究

Research on influencing factors of N_(2) huff and puff enhanced oil recovery in heavy oil reservoirs Bohai S Oilfield

为探究渤海稠油油藏氮气吞吐开发的可行性,开展了渤海S油田注气相态变化室内实验和长岩心氮气吞吐物理模拟实验,对氮气吞吐提高采收率及其影响因素进行了研究。实验结果表明:1)渤海S油田稠油注入氮气后,饱和压力迅速上升,原油膨胀因子及密度基本无变化;2)通过长岩心装置对S油田开展4个轮次吞吐实验,可提高采收率24.42%,而且产油量主要在前3个吞吐周期;3)原油黏度越低,储层渗透率越大,生产压力越低,氮气吞吐效果越好。因此,实施氮气吞吐时,可通过改善储层渗透率,制定合理的生产压力来提高吞吐效率。该认识对海上稠油油田注气吞吐开发具有重要意义。

In order to explore the feasibility of N_(2) huff and puff development in the heavy oil reservoirs in Bohai S Oilfield,the gas injection phase change experiment and long core N_(2) huff and puff physical simulation experiment were carried out,and the enhanced oil recovery by N_(2) huff and puff and its influencing factors were studied.The experimental results show that:1)The saturation pressure rises rapidly,and the expansion factor and density of crude oil are unchanged after injectingN_(2) into the heavy oil reservoir in Bohai S Oilfield;2)The oil recovery is increased by 24.42%,and most oil is produced in the first three huff and puff cycles after four cycles of huff and puff experiments with long core device;3)The lower the crude oil viscosity,the greater the reservoir permeability and the lower the production pressure,and the better the N_(2) huff and puff effect.Therefore,the huff and puff efficiency can be improved by improving the reservoir permeability and making a reasonable production pressure difference when N_(2) huff and puff is implemented.The understanding is of great significance to the development of gas injection huff and puff in offshore heavy oil fields.