在非混相条件下将CO2和其它常规气态注入物质与泡沫同时注入提高重油采收率

在上游工业中把注气工艺作为压力保持和IOR方法已有较长一段历史。证实添加泡沫是一种减小均质和非均质储层中气体流度的方法。然而泡沫气是一种在孔隙介质中获得流度控制的有前途的试剂。泡沫气对不同注气应用效果的显著作用强烈吸弓I着石油工业考虑用泡沫气提供世界未来的油气需求。     

原油组分对CO2最小混相压力的影响

为研究原油组分对CO2与原油最小混相压力的影响程度,在不同压力条件下开展两组细管驱油实验。结果表明,当原油中组分C5-C9和C10-C14含量降低,C15-C19、C20-C24和C25-C33含量增加时,CO2与原油最小混相压力升高至36 MPa,较第1组实验最小混相压力上升约5.88%。     

注二氧化碳（CO2）提高原油采收率

本文重点讨论了注CO2提高原油采收率的历程，并列举出15个大的CO2注入方案。同时也对CO2的来源及供应作了说明。最后评价了注CO2的前景。     

CO2-原油混相带形成机理与表征方法

CO2-原油混相带对CO2驱开发效果具有重要影响,目前尚未提出合理的混相带表征方法。通过理论分析和组分数值模拟,对CO2-原油混相带形成机理与表征方法进行系统研究,结果表明:混相带的形成受CO2与原油间的汽化-凝析作用主导,混相带形成之后的演化主要受水动力弥散作用影响;将油气界面张力等于0.1 dyn/cm的等值线作为混相带后缘,将油相中CO2含量为0.2的等值线作为混相带前缘,混相带宽度等于无因次混相带面积与混相带前缘包络线的长度之比;随着累积注入量的增大,在混相带前缘突破之前,混相带宽度逐渐增大,但增速会逐渐减慢,在混相带前缘突破之后到混相带后缘突破之前,混相带宽度迅速下降,之后趋于平稳。基于混相带的准确表征,可为开展混相带调控改善CO2驱开发效果提供基础。     

CO2与原油混相及非混相条件下渗流机理差异

在CO2的资源化利用获得广泛认识的同时,CO2提高采收率技术得到深入发展.研究CO2驱替过程中气、液组分变化有利于发现CO2-原油混相或非混相状态对渗流特征影响的原因.采出程度、含水及气油比等变化规律显示CO2在孔隙中具有独特的渗流特征.相同驱替量的情况下,非混相状态较早进入含水快速上升期,采出程度平缓增长,而混相状态的采出程度则保持较长时间的线性增长.组分分析结果显示, CO2驱替过程中油、气组分变化具有相似的变化规律.除此之外,混相状态的 CO2易于与油相组分作用,而非混相状态的CO2则偏向于与气相组分作用,说明混相或非混相状态时CO2与原油的作用方式不同.     

借助水平井混相水气交替注入法提高原油采收率

阿尔派恩油田位于阿拉斯加北坡上，在普鲁德霍湾油田以西48km处。该油田目前全部采用水平井开发，用混相水气交替注入方法驱油，与原来的开发方案相比，采用目前的新开发方案，预计增加可采储量1034万m^3，提高采收率6．5％。     

基于GPR-DE模型的CO2-原油体系最小混相压力研究

在对中外35个CO2驱油藏注入气体组分、油藏温度、原油组分、注入气体临界温度和最小混相压力进行数据统计和处理的基础上,结合高斯过程回归(GPR)与差分进化算法(DE),建立了预测CO2-原油体系最小混相压力的新模型——GPR-DE模型.利用统计误差和图形误差评价GPR-DE模型的精确度,利用实验数据和敏感性分析对模型结...     

注CO2提高原油采收率

如果CO2的价格不太昂贵又具有一定的数量，那么注CO2是一种行之有效的提高原油采收率方法。对于北海的许多砂岩储层来说，当地层压力高于20～22兆帕时，注CO2使气与油混相，而其他(例如氮气和烟道气)混相时地层压力要求高于26～29兆帕。地层条件下CO2的密度为400～700公斤／立方米，大大高于     

CO2-原油细管试验混相判定新方法

最小混相压力（MMP）是CO2混相驱设计中的一个重要参数，细管试验是其标准确定方法。通过常规细管试验及MMP值附近的加密试验，发现采收率在MMP附近呈曲线变化，使得采用线性拟合取交点判定MMP的方法具有较大主观性，且结果会偏小；此外，原油性质及装置设计会明显影响最终采收率，不可将采收率作为混相评价标准。以改进的三次样条插值方法为基础，提出了以插值曲线曲率最小处为MMP的新判定方法，并采用新方法重新处理了文献中的细管试验数据，将计算结果与文献给出值进行了对比。结果表明，传统的线性拟合取交点的判定方法使结果平均偏小1．4MPa，而新方法可消除主观因素的影响，更适合作为标准判定方法。     

CO2混相驱提高原油采收率的研究现状及发展前景

针对我国低渗透油藏自然产能低、地层能量不足、地层压力下降快等引起采收率低的现状,分析了CO2混相驱的机理,包括CO2在原油中溶解度对原油粘度、体积、表面张力的影响,比较了几种气体在原油中的溶解度,以及溶解气量对油-水界面张力的影响,总结了CO2驱的几种作用方式,主要有一次接触混相驱、多次接触混相驱和轻质油加CO2混相驱,现场应根据实际情况选择合理的CO2混相驱作用方式。最后给出了CO2混相驱的应用实例及效果,展望了CO2混相驱发展前景。     

CO2混相驱驱油方式对榆树林油田采收率影响研究

CO_2混相驱中为减少气体发生指进,现场常用水气交替注入方式。为了研究CO_2混相驱不同水气驱方式对大庆榆树林油田提高采收率效果的影响,在长岩心上进行了采油工艺实验,研究了气体段塞总量和交替注入气体小段塞大小、含油饱和度大小和水气比对采收率的影响,结果证明了同条件下这些都是CO_2混相驱很重要的因素,注入气体0.3到0.4PV最佳,混相条件下最佳的水气交替驱工艺是至少要有先注入或者间断注入至少一个CO_2的0.1 PV以上的段塞,同条件下提高采收率最大。     

Modeling CO2 miscible flooding for enhanced oil recovery

The injection of fuel-generated CO2 into oil reservoirs will lead to two benefits in both enhanced oil recovery (EOR) and the reduction in atmospheric emission of CO2. To get an insight into CO2 miscible flooding performance in oil reservoirs, a multi-compositional non-isothermal CO2 miscible flooding mathematical model is developed. The convection and diffusion of CO2-hydrocarbon mixtures in multiphase fluids in reservoirs, mass transfer between CO2 and crude, and formation damages caused by asphaltene precipitation are fully considered in the model. The governing equations are discretized in space using the integral finite difference method. The Newton-Raphson iterative technique was used to solve the nonlinear equation systems of mass and energy conservation. A numerical simulator, in which regular grids and irregular grids are optional, was developed for predicting CO2 miscible flooding processes. Two examples of one-dimensional (1D) regular and three-dimensional (3D) rectangle and polygonal grids are designed to demonstrate the functions of the simulator. Experimental data validate the developed simulator by comparison with 1D simulation results. The applications of the simulator indicate that it is feasible for predicting CO2 flooding in oil reservoirs for EOR.     

Mechanism of CO2 enhanced oil recovery in shale reservoirs

Combined with NMR,core experiment,slim-tube tests,nano-CT and oil composition analysis,the mechanism of CO2 enhanced oil recovery had been studied.CO2 flooding ...     

注二氧化碳提高煤层气采收率实验系统设计

针对我国煤层气开发中存在的产气率低、回采周期长的问题以及CO2排放量大、污染环境严重等现象,研制了一套可以进行煤层气吸附／解吸性能评价及注CO2开采煤层气模拟的实验系统。利用该系统开展了不同气体在煤岩中的吸附／解吸性能评价研究和注CO2开采煤层气效果实验研究。实验结果表明,CO2在煤岩中的吸附量明显高于CH4的吸附量;与自然降压开采相比,注CO2可以提高煤层气的采收率,提高幅度在10％以上。而且随CO2注入量的增加,煤层气采收率增大。     

Investigation of immiscible CO2 and C1 injection and comparison with water injection for enhanced oil recovery in naturally fractured reservoirs

Reservoir oil and gas content tends to rise up to the surface as long as their potential energy levels are sufficient. In order to amplify this energy, either during the time when oil is uprising on its inherent energy or since after, so as to facilitate the traveling of oil to the surface, enhanced oil recovery (EOR) methods come into play. Furthermore, the increasing demand for oil from one hand, and the shrinkage of producible reserves on the other hand, have made it unavoidable to undertake EOR techniques. Built in this research was a 10-element model of reservoir fluid to simulate its behavior. Furthermore, slim tube simulation was undertaken to determine minimum miscibility pressure for various gases. Then, different scenarios of natural depletion, CO₂ injection, methane injection, and water injection were simulated by ECLIPSE 300 software package with the results of different scenarios compared. The results indicated water injection to be associated with higher recovery factor.     

Evaluation of miscible and immiscible CO2 injection in one of the Iranian oil fields

Carbon dioxide (CO₂) flooding is one of the most important methods for enhanced oil recovery (EOR) because it not only increases oil recovery efficiency but also causes a reduction of greenhouse gas emissions. It is a very complex system, involving phase behavior that could increase the recovery of oil by means of swelling, evaporation and decreasing viscosity of the oil. In this study, a reservoir modeling approach was used to evaluate immiscible and miscible CO₂ flooding in a fractured oil field. To reduce simulation time, we grouped fluid components into 10 pseudo-components. The 3-parameter, Peng–Robinson Equation of State (EOS) was used to match PVT experimental data by using the PVTi software. A one-dimensional slim-tube model was defined using ECLIPSE 300 software to determine the minimum miscibility pressure (MMP) for injection of CO₂. We used FloGrid software for making a reservoir static model and the reservoir model was calibrated using manual and assisted history matching methods. Then various scenarios of natural depletion, immiscible and miscible CO₂ injection have been simulated by ECLIPSE 300 software and then the simulation results of scenarios have been compared. Investigation of simulation results shows that the oil recovery factor in miscible CO₂ injection scenario is more than other methods.     

缝洞型碳酸盐岩油藏岩溶储集体注氮气提高采收率实验

缝洞型碳酸盐岩油藏储集空间类型多样,形态复杂,在水驱过程中容易形成阁楼油和绕流油,采用气驱能够有效补充地层能量,提高剩余油的采出程度。为观察缝洞型油藏中注入气体的驱油动态,根据塔河油田实际地质资料和注采特征,依据相似性原则,设计制作二维缝洞型油藏可视化物理模型,开展缝洞型油藏岩溶储集体模型注气提高采收率实验研究。结果表明:以注气速度分别为20和5 mL/min进行驱替,宏观油水界面特征基本相似,在氮气驱替过程中会出现明显的气水同锥现象和气水协同效应;注气速度为20 mL/min下的最终采出程度约为70.5%,注气速度为5 mL/min下的最终采出程度约为78.9%,注气速度高易发生气窜,低注气速度可以延长注氮气时间,防止气体过早发生气窜,但是由于速度低,驱动能量低,氮气只能进入阻力相对较小的溶洞和裂缝中。因此,合理控制注气速度能够充分发挥气驱提高采收率的潜能。     

Experimental study of enhanced oil recovery by CO2 huff-n-puff in shales and tight sandstones with fractures

The fractures and kerogen,which generally exist in the shale,are significant to the CO2 huff-n-puff in the shale reservoir.It is important to study the effects ...     

Estimation of the CO2-oil minimum miscibility pressure for enhanced oil recovery

The authors' aim was to present new models based on artificial neural network (ANN) and two optimization algorithms including cuckoo optimization algorithm (COA) and teaching learning based optimization (TLBO) to predict the pure and impure CO₂ MMP. Thirty-four and 11 training and testing data sets were used to develop these models with following inputs: reservoir temperature, the mole percent of volatile oil components (C₁ and N₂), mole percent of intermediate oil components (C₂-C₄, CO₂, and H₂S), molecular weight of C₅₊ fraction in oil phase (MW_C5+) and mole percentage of CO₂, N₂, C₁, C₄, and H₂S in the injected gas. Statistical comparisons show that although two models yield acceptable results, the ANN-TLBO model has better performance with the lower mean absolute percentage error (2.6%) and standard deviation (3.37%) and the higher coefficient of determination (0.993). Moreover, among the available correlations, the Cronquist's (1978 Cronquist, C. (1978). Carbon dioxide dynamic miscibility with light reservoir oils. Fourth Annual U.S. DOE Symposium, Tulsa, Oklahoma. [Google Scholar]; corrected by Sebastian et al., 1985 Sebastian, H. M., Wenger, R. S., and Renner, T. A. (1985). Correlation of minimum miscibility pressure for impure CO2 streams. J. Pet. Technol. 37:2076–2082.[Crossref] , [Google Scholar]) correlations have better performance. Finally, the sensitivity analysis on the ANN-TLBO showed that MW_C5+ and reservoir temperature are the most influential parameters in determining the CO₂ MMP, respectively.