低渗透油藏CO_2驱油机理及应用现状研究

当今社会快速发展,能源问题日益严峻。由于低渗透油藏低孔、低渗、自然能量不足等特点,采用常规方法已经不能有效采出原油,CO_2驱是三次采油方法中提高低渗透油藏采收率的一种方法。综述了CO_2驱油的机理、CO_2驱油效果的影响因素以及近些年来国内外CO_2驱油的应用现状,指出CO_2驱在我国低渗透油藏的可行性和巨大潜力。     

CO2驱提高采收率国内外发展应用情况

本文主要叙述了利用CO2驱提高采收率的历史及目前国内外的发展现状,我国在大庆、胜利、任丘、江苏等油田先后开展了二氧化碳驱油实验。CO2驱开采一般是在不适合注蒸汽开采的油田进行。这类油田的油藏地质条件是：油层薄,或埋藏太深,或渗透率太低,或含油饱和度太低等。注CO2可有效提高这类油藏的采收率。     

CO_2驱提高采收率机理及认识

针对高压低渗油藏开发效果差,注水难度大的情况,本文详细介绍了CO2驱提高低渗油藏采收率机理,并结合高89-1块注CO2先导实验区矿场实验取得的开发效果进一步深入研究,结论及认识为同类型低渗透油藏提高采收率提供借鉴。     

延长油田低渗透油藏二氧化碳驱油影响因素室内实验研究

针对延长油田低渗透油藏,通过开展岩心注气物理模拟实验,探索提高低渗透油藏CO2驱油开发效果影响因素及其规律。实验表明,不同驱替压力下,注入压力越高,采收率越高,注入压力高于最小混相压力后,采收率不再增加,采收率最高可达66.68%;并且注入压力增加,气体突破时间延迟;注入速度越高,采收率和换油率越高,CO2驱油开发效果越好,生产汽油比也越高;岩心渗透率高于1.26×10-3μm2时,渗透率增大,采收率差别不大,但相比水驱,采收率提高程度较大;岩心渗透率低于1.26×10-3μm2时,渗透率增大,采收率增大,但相比水驱,采收率提高程度较小。     

二氧化碳驱油

多年来,国内外许多学者对油藏使用CO2提高原油采收率进行了研究,室内实验和现场应用都证明,CO2是一种高效驱油剂。CO2驱是油田三次采油提高原油采收率的一项重要手段。针对这一问题,本文主要介绍CO2驱油机理:降粘作用、膨胀作用,驱油方式:CO2混相驱,高压注CO2气体等,并对现场实施效果进行分析,总结出驱油效果的影响因素及其规律,为油田生产提供指导。     

低渗透油藏表面活性剂降压增注机理研究

低渗透油藏是我国重要石油资源组成部分,大多数的低渗透油田以注水开发方式为主,低渗透油藏普遍存在着孔喉细小、渗透率低、渗流阻力大等特征,从而导致注水驱替压力较高、注入速率低、采收率低等一系列的问题。压裂技术对低渗透储层改造起到了一定的作用,但是作用时间和范围非常有限。因此,对低渗油藏表面活性剂驱替及降压增注机理的研究,在低渗油藏开发中意义重大。主要对低渗油藏降压增注用表面活性剂的驱油机理方面做了综述,对低渗透油藏化学驱的现场应用提供一定帮助。     

储层非均质性对二氧化碳驱效果影响研究

CO2驱油技术是目前油田上提高采收率的重要技术之一。影响其 CO2驱油效果因素较多。油藏非均质性是其中一个的重要因素,因此需要开展油藏非均质性对 CO2驱油效果影响的系统研究,幵在此基础上迚一步研究改善非均质油藏 CO2驱效果的方法。研究了层间非均质和存在窜流通道情况下,CO2驱变化规律,分析了两种非均质性对 CO2驱效果影响。结论阐明了两种非均质性对 CO2效果的影响程度。     

高89-1块特低渗透油藏CO_2驱提高采收率先导试验

针对胜利油田特低渗透油藏常规开发方式地层能量补充困难、采收率低的特点,探索了CO2驱改善特低渗透油藏开发效果、提高采收率的方法。在CO2驱提高采收率室内实验研究的基础上,优化设计了CO2驱油藏工程方案。从方案实施效果来看,在低渗透油藏实施CO2驱,可有效补充地层能量,提高油井产能。针对注气现场实施过程中出现的气窜现象开展的研究表明:地层压力低与混相压力、储层非均质性强和存在裂缝是造成气窜的主要因素,保持地层压力达到混相压力、采取矢量化的注气井网以及采取合理注采调控措施可以减缓气窜发生,提高注气开发效果。     

水驱后凝胶与表活剂交替注入驱油效果

针对裂缝性低渗透油藏注入水易沿裂缝突进、含水上升快、水驱效果不理想的情况,开展了水驱后凝胶与表活剂交替注入方式提高采收率室内实验研究。通过室内凝胶体系成胶特性和稳定性评价,筛选出与实际油藏区块注入水配伍的凝胶体系。选择甜菜碱两性表面活性剂用于活性剂驱,开展了双管并联岩心体系驱油效果研究。研究结果表明:凝胶与表活剂交替注入可明显提高注入压力,该体系的采收率平均值为12.03%,低渗岩心的采收率略高于高渗透岩心采收率。与表活剂驱、聚合物与表活剂交替注入相比,驱油效果更好,可以作为裂缝性低渗透油藏水驱后进一步提高采收率的技术。     

注CO2气驱提高采收率效果影Ⅱ向因素分析

目前油田常规注水开发难度不断增加,应用注CO2气驱技术能够有效解决注水困难等问题,提高了原油采收率。在室内实验研究的基础上,应用数值模拟技术优化了注气方式及注气时机;分析了油藏地质参数对注CO2气驱提高采收率的影响。研究表明：水气交替注入方式更优;非均质性越强,开发效果越差;油藏渗透率越大、含油饱和度越高、原油粘度越低,注CO2驱油效果越好。     

为强化石油回采捕集CO2的全周期评估

The development and deployment of Carbon dioxide Capture and Storage （CCS） technology is a cornerstone of the Norwegian government＇s climate strategy. A number of projects are currently evaluated/planned along the Norwegian West Coast, one at Tjeldbergodden. COe from this project will be utilized in part for enhanced oil recovery in the Halten oil field, in the Norwegian Sea. We study a potential design of such a system. A combined cycle power plant with a gross power output of 832 MW is combined with CO2 capture plant based on a post-combustion capture using amines as a solvent. The captured CO2 is used for enhanced oil recovery （EOR）. We employ a hybrid life-cycle assessment （LCA） method to assess the environmental impacts of the system. The study focuses on the modifications and operations of the platform during EOR. We allocate the impacts connected to the capture of CO2 to electricity production, and the impacts connected to the transport and storage of CO2 to the oil produced. Our study shows a substantial reduction of the greenhouse gas emissions from power production by 80% to 75 g·（kW·h）^-1. It also indicates a reduction of the emissions associated with oil production per unit oil produced, mostly due to the increased oil production. Reductions are especially significant if the additional power demand due to EOR leads to power supply from the land.     

Experimental Study of In-Situ CO<Subscript>2</Subscript> Foam Technique and Application in Yangsanmu Oilfield

The Yangsanmu oilfield of Dagang is a typical heavy oil reservoir. After the maximum primary production (waterflooding), more than half of the original oil is still retained in the formation. Therefore, the implementation of an enhanced oil recovery (EOR) process to further raise the production scheme is inevitable. In this work, a novel in-situ CO₂ foam technique which can be used as a potential EOR technique in this oilfield was studied. A screening of gas producers, foam stabilizers and foaming agents was followed by the study of the properties of the in-situ CO₂ foam systems through static experiments. Core-flooding experiments and field application were also conducted to evaluate the feasibility of this technique. The results indicated that the in-situ CO₂ foam system can improve both the sweep and displacement efficiencies, due to the capacity of this system in reducing oil viscosity and interfacial tension, respectively. The EOR performance of the in-situ CO₂ foam system is better than the single-agent and even binary system (surfactant-polymer) flooding. The filed data demonstrated that the in-situ CO₂ technique can significantly promote oil production and control water cuts. These results are believed to be beneficial in making EOR strategies for similar reservoirs.     

CO_2驱油提高采收率技术的研究现状与分析

针对化石能源利用过程中排放CO_2引起的温室效应问题,同时为满足油藏高效开发的要求,介绍一种CO_2驱油提高采收率技术,分析其驱油机理,并总结目前国内外EOR技术的应用与开发现状,指出目前我国EOR应用的前景。     

Spontaneous emulsification aspect of enhanced oil recovery

Recent studies have suggested the possibility of spontaneous emulsification as a mechanism for enhanced oil recovery (EOR). The discussions have, however, remained essentially qualitative. A study was therefore undertaken to estimate quantitatively the contribution of spontaneous emulsification as an EOR mechanism. The tests were conducted on several bulk liquid/liquid systems as well as by displacement experiments in unconsolidated synthetic sand packs. Spontaneous emulsification was found to be a mechanism for EOR: the estimated extra contribution to EOR due to this mechanism was found to be significant in laboratory scale displacement experiments. Tertiary recovery was always greater when spontaneous emulsification was evident than otherwise. Results of tests on bulk liquid/liquid systems indicate that the occurrence or absence of spontaneous emulsification can be correlated with the values of ‘partition parameter’. It may be concluded that higher oil recoveries may be achieved in chemical EOR processes where interface mass transfer (and the accompanying spontaneous emulsification) occurs. The evaluation of efficiency of residual oil mobilisation through the capillary number theory (with and without spontaneous emulsification) is also discussed. Displacement tests with spontaneously emulsifying systems showed that residual oil left behind a conventional waterflood was mobilised in a range of capillary numbers much less than that which applies to low-tension waterfloods.     

低渗油藏表面活性剂驱油体系优选

针对低渗油藏渗流阻力大、注水压力高及水驱采收率偏低的问题,通过性能评价,优选一种适合该类油藏的表面活性剂驱油体系。以研制的阴非离子型表面活性剂(GJ剂)为主剂,其它表面活性剂为助剂,分别考察其油水界面张力、润湿性、防膨性、洗油效率、驱油效率。结果表明,GJ+YJ体系与原油界面张力为6.15×10-3mN/m,该体系可使油湿岩片接触角由76.80°降低至48.83°,防膨率达66.63%,洗油效率为61.28%,驱油效率提高11.80%。因此,GJ+YJ体系在低渗油藏改善水驱效果中具有良好的应用前景。     

低渗砂岩岩心AESO3表面活性剂驱油室内效果评价

随着我国低渗透油田步入三次采油阶段,三次采油用表面活性剂的研究成为当前研究的重点。ZC油田长2储层是典型的低渗透储层,本次为其选取了AESO3表面活性剂,其抗盐性与表面张力均符合长2储层流体的要求,本次选用的表面活性剂可以将储层驱油效率平均提高5.7%,将储层水相渗透率平均提高10%。     

国内轻质油藏注空气、空气泡沫提高采收率效果分析

在重点调研国内油田空气、空气泡沫驱的基础上,论述了注空气、空气泡沫低温氧化技术的原理,对我国油田开展注空气、空气泡沫驱技术的实际效果以及潜力进行了的分析,认为注空气低温氧化工艺技术安全可控,不但可以解决我国储量丰富的低渗透油藏所面临的开发难题,而且可以进一步提高水驱、聚合物驱后油藏的采收率。随着技术进步,注空气低温氧化技术是我国乃至全世界注气提高采收率技术发展的必然趋势。并通过对现场应用情况分析,给出了对轻质油藏注空气、空气泡沫提高采收率的一些建议。     

微乳液泡沫驱油技术原理、挑战和研究进展

微乳液驱和泡沫驱是强化采油领域中的两个重要技术。前者利用表面活性剂形成油-水微乳液提高增溶能力,降低油水界面张力和毛细管阻力,从而提高驱替效率和微观采收率;后者利用泡沫剂将气体稳定地分散在水相中,在油藏孔隙中形成泡沫,封堵优势通道和已驱替区域,从而扩大波及体积并提高宏观采收率。通过综述两个技术的国内外发展历史和研究进展,阐明了其优势和局限性。近年来提出的微乳液泡沫驱油技术,又称为低张力泡沫驱,其既可以保留两个独立技术的优势,又可以克服他们的缺点,最终同时提高微观和宏观采收率。但是在实际研究中,微乳液泡沫驱技术却面临理论和应用上的双重挑战。通过调查国内外相关研究进展,详细阐述了微乳液泡沫驱技术目前面临的挑战、研发思路和研究建议。     

微乳液泡沫驱油技术原理、挑战和研究进展

微乳液驱和泡沫驱是强化采油领域中的两个重要技术,可以分别提高驱油过程的微观和宏观采收率.通过综述两个技术在国内外的发展历史和研究进展,阐明了其优势和局限性,并引出结合两者优势的新型采油技术:微乳液泡沫驱,又称为低张力泡沫驱.虽然此新型技术可以同时提高微观和宏观采收率,但是在实际应用中,仍然面临理论和应用上的双重挑战,如...