海上稠油油藏“调驱+热采”提高采收率实验研究

Research on enhancing recovery efficiency by “profile controlling and thermal recovery” in offshore heavy oil reservoir

关键词:  稠油油藏  调驱  热采  物理模拟 

Key words:  heavy oil reservoir  profile controlling  thermal recovery  physical simulation

摘要:

渤海稠油油藏具有原油黏度高、油层渗透率高和非均质性严重等特点,常规注水开采时油井产能低,开发效果差,亟待采取强化措施来改善水驱开发效果。以油藏工程、物理化学和热力学等理论为指导,以仪器分析、化学分析和物理模拟等为技术手段,以渤海NB35-2油藏储层地质和流体为实验平台,开展了调驱、热力采油和“调驱+热力”联合作业增油效果实验研究和机理分析。结果 表明,与采用蒸汽发生器向岩心内注入高温高压蒸汽的实验方法相比,通过在岩心中不同区域饱和不同黏度原油来模拟热流体注入即热采过程,不仅能够更好地模拟热采过程中储层内原油黏度分布,而且技术简单。与单独热采或调驱措施相比较,“调驱+热采”联合作业增油效果较好,并且采收率增幅大于二者之和,产生了协同效应。“调驱+热采”联合作业优化工艺参数:Cr³⁺聚合物凝胶段塞尺寸范围为0.025 PV~0.075 PV,CP为1 200~1 600 mg/L,m(聚)∶m(Cr³⁺)=(180∶1)~(270∶1)。热流体作用范围小于3/10注采井距,作用范围内原油黏度50～120 mPa·s。 

Abstract:

There are characteristics as high viscosity of crude oil, high reservoir permeability and serious heterogeneity of heavy oil reservoir in Bohai, which result in low productivity of oil wells and poor development effect. Therefore it is urgent to take reinforcing measures and enhance development effect of water flooding. Theoretically guided by reservoir engineering, physical chemistry and thermodynamics, by means of instrument analysis, chemical analysis and physical simulation, taking reservoir geology and fluid of Bohai NB35-2 as experimental platform, research on the effect of enhancing oil productivity was carried out, with using profile controlling, thermal recovery and combination of them, also its mechanism was analyzed. Results showed that, compared with experimental method that injecting high temperature high pressure steam into the core, this method simulated injection of thermal fluid with different viscosity through saturating different areas in core(naming thermal recovery process). The method was not only simple but could better simulate the distribution of crude oil in the reservoir during the process of thermal recovery. Compared with single thermal recovery or profile controlling, the effect of enhancing oil productivity of “profile controlling + thermal recovery” was better, the oil recovery was more than the sum of each single measure, which produced synergistic effect. Optimization of process parameters of combination process was given:range of Cr³⁺ polymer gel plug size was 0.025～0.075 PV, CP=1 200～1 600 mg/L and the ratio of polymer and Cr³⁺ was(180∶1)～(270∶1). Thermal fluid scope was less than 3/10 of injector producer distance, within which the viscosity of crude oil was from 50 to 120 mPa·s.