Monitoring the Effect of Discontinuous Shales on the Surfactant Flooding Performance in Heavy Oil Reservoirs Using 2D Glass Micromodels

Although most heavy oil reservoirs contain discontinuous shaly structures, there is a lack of fundamental understanding how the shaly structures affect the oil recovery efficiency, especially during surfactant flooding to heavy oils. Here, an experimental study was conducted to examine the effect of discontinuous shales on performance of surfactant flooding by introducing heterogeneities to represent streaks of shale in five-spot glass micromodels. Results show that oil recovery in presence of shale streak is lower than in its absence. Based on the authors’ observations, the presence of flow barriers causes premature breakthrough of injected fluids and also an unstable displacement front. As well, displacement efficiency of surfactant flooding is dependent strongly on the shale distribution configuration. Increasing shale content causes reduction of ultimate oil recovery and also severe fingering during water flooding while it compensates during surfactant flooding considerably. In shaly patterns, in the case of surfactant flooding, the oil recovery after breakthrough increases significantly, while it changes much less for the case of water flooding as well as flooding in homogeneous model. Oil recovery efficiency and breakthrough time improved with increasing surfactant concentration. However, beyond a specific limit of sodium dodecyl sulfate concentration, around 2000 ppm, incremental oil recovery becomes insignificant. Presence of connate water in surfactant flooding scheme can improve the recovery efficiency in shaly patterns. Results of this work can be helpful to investigate the optimal location of injection/production wells during enhanced oil recovery schemes in shaly reservoirs using five-spot micromodels.     

Status of Dual-Continuum Models for Naturally Fractured Reservoir Simulation

Abstract

Naturally fractured reservoirs (NFR) contain significant portions of the world's proven reserves of conventional oil. However, their simulation is one of the most challenging and computationally intensive problems in reservoir engineering. Most commercial reservoir simulators use dual-continuum models to predict performance of an NFR where two overlapping continua for the fracture and matrix medium are considered. Then transfer of multiphase fluid between the two media is taken into consideration by a source-sink transfer function (Zhang and Sun, 2000 Zhang, D. and Sun, A. Y. 2000. Stochastic analysis of transient saturated flow through heterogeneous fractured porous media: A double-permeability approach. Water Resour. Res., 36: 865–874. [Crossref], [Web of Science ®] , [Google Scholar]). After review of different conceptual models to simulate an NFR, major pitfalls related to dual-porosity and dual-permeability models for simulation of such reservoirs will be discussed briefly within this article.     

The Applicability of Expanding Solvent Steam-Assisted Gravity Drainage (ES-SAGD) in Fractured Systems

Abstract

The aim of this contribution is to evaluate the performance of an expanding solvent steam assisted gravity drainage (ES-SAGD) process in naturally fractured systems. Steam-assisted gravity drainage (SAGD) and ES-SAGD processes have been investigated in both conventional and fractured reservoir models and the effect of networked fractures on the recovery mechanism and performance of ES-SAGD has been investigated. Operational parameters such as steam quality, vertical distances between wells, and steam injection temperature have been also evaluated. Finally, to study the effect of a well's horizontal offset, a staggered ES-SAGD well configuration has been compared to a stacked ES-SAGD.     

复杂裂缝性油藏分阶段数值模拟及剩余油分布预测——以火烧山油田$H^1_4$层为例

复杂裂缝性油藏在开发过程中经多次措施,使其各类属性参数发生了明显的变化,突出表现为双重介质、开发阶段分明等特点。以火烧山复杂裂缝性油藏为例,利用分阶段双重介质数值模拟方法,进行了复杂裂缝性油藏数值模拟,较准确地预测了复杂裂缝性油藏开发中后期剩余油分布,并在生产实际中获得显著效果。     

Visualization and Quantification of Asphaltinic-Heavy Oil Displacement by Co-Solvents at Different Wettability Conditions

Abstract

Despite numerous experimental studies, there is a lack of fundamental understanding on how the chemical composition of a co-solvent at different wettability conditions might affect the pore-scale events and oil recovery efficiency in 5-spot models. In this study visualization of solvent injection experiments performed on a one-quarter five spot glass micromodel, which was initially saturated with the crude oil. One hydrocarbon solvent was considered as base, and four other groups of commercial chemicals, as well as their mixtures, were used as co-solvents. Microscopic and macroscopic displacement efficiency of solvent mixtures in both strongly water-wet and oil-wet media has been studied. It has been observed that small aggregates of asphaltene can improve oil recovery to some extent during early stages of solvent injection. Different groups of chemicals showed various effects on oil recovery based on their nature. An optimum mixture with some percent of commercials containing alcohol group with greatest sweep efficiency was found. The observations confirmed that the presence of connate water in strongly water-wet medium could improve the final recovery, while the effect of wettability in absence of connate water was at minimum.     

溶剂辅助重力泄油技术开采稠油室内试验

多孔介质和Hele-Shaw设备中的溶剂辅助重力泄油开采机理不同,特别是两者产生脱沥青作用的压力范围是否一致及增产幅度的差别程度如何尚不明确。为研究溶剂辅助重力泄油技术开采多孔介质中稠油的机理,建立了3层结构的溶剂辅助重力泄油可视化填砂模型,对高渗岩心溶剂辅助重力泄油不同注入压力与泄油速率关系及相同注入压力下不同渗透率岩心溶剂辅助重力泄油脱沥青降黏作用和堵塞流动通道的复合作用机理进行了室内试验研究。试验结果表明:多孔介质溶剂脱沥青作用出现在饱和蒸气压附近,试验泄油速度提高3倍,但脱沥青作用发生的压力范围较小;脱沥青作用会造成低渗地层部分孔喉堵塞。因此,低渗地层VAPEX溶剂注入压力应低于溶剂的饱和蒸气压,而高渗地层则可以充分利用脱沥青降黏作用来提高泄油速率。      

An Experimental Investigation of Silica Nanoparticles Effect on the Rheological Behavior of Polyacrylamide Solution to Enhance Heavy Oil Recovery

The use of polymer flooding as one of enhanced oil recovery methods has recently increased. The occurrence of high shear rates in reservoir and near well bore through perforation nozzles during polymer flooding cause shear degradation of polymers and therefore polymer viscosity has decreased. Rheological behavior of polymer solution in different conditions of oil reservoir is one of the key factors to develop use of polymer solutions. A few researches are available regarding improving rheological behavior of polymeric solution. In this study, to investigate the effect of nanoparticles on rheological behavior of polymer solutions two samples were prepared: polyacrylamide solution in water and suspension of silica nanoparticles in polyacrylamide solution. The sample viscosities in different shear rates were measured. The best rheology models were developed to state rheological behavior of prepared samples and the measured data were compared to power law model. An increase in the viscosity of the suspension solution with respect to polymer solution in different shear rates was observed. Rheological analysis showed that power law model is a good rheology model to demonstrate rheological behavior of suspension in low and medium shear rates and is an acceptable model for polymer solution in low shear rates. Two types of flooding test were performed in a glass micromodel: flooding by polyacrylamide solution and suspension of silica nanoparticles in polyacrylamide solution. The results of flooding test showed a 10% increase in oil recovery for nanosuspension solution in comparison with polymer solution after one pore volume fluid injection.     

油溶性降黏剂降黏性能研究

针对胜利油田现河稠油,研究了7种油溶性降黏剂(Y-1～Y-7)及其复配体系的降黏性能,考察了降黏剂加量、原油含水率对降黏效果的影响,研究了降黏剂对蒸汽驱油效果的影响。结果表明:当油溶性降黏剂质量分数小于5%时,原油降黏率随降黏剂加量的增加而迅速增大,之后增加缓慢,加量为15%时的降黏率可达90%以上(Y-4除外)。Y-3和Y-7按质量比1:1复配后的降黏效果最好,总加量5%、10%时的原油降黏率分别为76.1%和93.14%。不含降黏剂时,随原油含水率增加原油黏度先增加后降低,原油含水50%时的黏度是不含水原油的3.9倍,形成W/O型乳状液。不同含水率下,加入降黏剂后原油黏度大幅降低;随含水率增加,原油降黏率先降低后增加,含水率10%时达到最低(Y-1除外)。稠油蒸汽驱前注入0.009～0.027 PV油溶性降黏剂,采收率增幅为2.8%～6.0%。     

克拉玛依稠油溶剂脱酸工艺研究

介绍了克拉玛依稠油采用溶剂脱酸工艺原理及工艺流程,考察了脱酸溶剂组成、脱酸温度、剂油质量比、原料流量对脱酸效果的影响。结果表明,利用流通截面积0．12cm^2的实验微反应器,当脱酸溶剂组成为氨：乙醇：水=6：50：40,脱酸温度80℃,原油流量800g／min,剂油质量比0．30时,一次脱酸率可达60％以上,抽出的石油酸纯度达75％以上,石油酸抽出率约占原油的2．3％。     

利用测井资料研究稠油油藏注汽前后物性变化规律--以河南油田为例

针对稠油注汽前后物性参数变化的问题，主要依据大量的录井资料、岩心分析资料、各类测井资料和动态监测等资料，从测井角度开展了物性变化规律研究，建立了孔、渗地质模型及多种参数计算方法。可为稠油开采、调整方案编制、增产挖潜提供可靠的参数资料及测井依据。     

An Investigation of and Comparison Between the Simulation of Miscible and Immiscible Gas Injection in an Undersaturated Fractured Reservoir in the South of Iran

M-Reservoir is a dual porosity fractured reservoir having active aquifer and heterogenous production zones. It had had only a total oil recovery of 8.4% with the total production of 240 MMSTB up to 2008. By simulation of slime tube experiment using Eclipse 300 software, minimum miscibility pressure of 3700 psia was obtained, which was below its average pressure. Production optimization and final recovery increment were performed via analyzing and matching of fluid reservoir, history matching of past reservoir performance, and investigating on different location of gas injected well. The best location of injected well was selected based on the recovery coefficient and gas injection method of miscible and immiscible at various rates and were compared with natural depletion in selected locations. The results represent that the miscible gas injection has more recovery coefficient than natural depletion and there is somewhat recovery coefficient in comparison with immiscible gas injection.     

Foamy Oil Formation by Gas Injection and the Effect on Heavy Oil Recovery

In this study, produced natural gas reinjection process is proposed to form renewed foamy oil for heavy oil recovery. A new experimental procedure was developed to prove that an in situ foamy oil could be formed during the gas injection process. A field scale numerical study was performed to further analyze foamy oil behavior and its influential mechanisms. The study showed that natural gas huff-n-puff process could increase heavy oil recovery by inducing foamy oil. The findings of this study could be useful to solve the problem of disappearance of foamy oil mechanism.     

裂缝性低渗透油藏三维两相黑油数值模拟研究

大量实验和现场数据表明,低渗透油藏中普遍存在启动压力梯度,并且裂缝对应力的敏感比基质更强,文中在双孔、双渗达西渗流的数学模型基础上引入启动压力梯度和应力敏感,建立了裂缝性低渗透油藏双孔、双渗渗流模型,并对其进行了全隐式联立求解以及实例计算。     

核磁共振测井在砂砾岩稠油油藏评价中的应用

胜利油区的宁海-王庄油田储层岩性复杂,油质稠,常规测井资料在产液性质、产层性质评价及储层参数计算等方面存在困难.核磁共振测井在该油田的有效储层划分、流体识别、孔隙结构研究等方面发挥了重要作用.但由于稠油粘度大,含氢指数低,也造成核磁共振测井的孔隙度、渗透率偏低.因此,在6口砂砾岩稠油井的核磁共振测井资料分析的基础上,提出了稠油校正方法,经稠油校正后,计算的储层参数更加准确,满足了砂砾岩稠油油藏精细评价的要求.     

The Determination of Effective Diffusivity Coefficients in a Solvent Gas Heavy Oil System for Methane

Abstract

In this investigation, an accurate high pressure and temperature diffusion setup was applied to measure the diffusion coefficients of methane in Iranian heavy oils in presence and absence of porous media by using the pressure-decay method. The solvent diffusivity in heavy oil was determined by both graphical and numerical methods. In addition, the effects of the porous medium and the temperature on the molecular diffusion coefficient of the solvent gas in the liquid phase were discussed and finally, using experimental data, a functionality dependence of molecular diffusivity on temperature and porous medium characteristics was proposed.     

应用迂渗理论描述裂缝性储层的剩余油分布

本文应用迂渗(percolation)理论,根据油藏裂缝特征参数,给出了油井周围裂缝系统延伸范围的分析计算和计算机模拟方法,从而解决了裂缝性油气藏自喷开采后剩余油分布区域的数学描述问题,为打加密井提高采收率确定布井方案提供了依据。文章列出了两个实例,计算和模拟结果与开发实际相一致。     

An Experimental Study of Surfactant Polymer for Enhanced Heavy Oil Recovery Using a Glass Micromodel by Adding Nanoclay

The nanotechnology has been widely used in several other industries, and the interest in the oil industry is increasing. Nanotechnology has the potential to profoundly change enhanced oil recovery (EOR) and to improve mechanism of recovery, and it chosen as an alternative method to unlock the remaining oil resources and applied as a new EOR method in last decade. Conventional production procedures give access to on average only one-third of the original oil in place, the use of surfactants and polymers allows for recovery of up to another third of this oil. Chemical flooding is of increasing interest and significance due to high oil prices and the need to increase oil production. Objective of this research is Identification of potential of nanoclay as an appropriate agent for improving the efficiency of surfactant polymer flooding in five-spot glass micromodels. In this work a series of solvent injection experiments was conducted on horizontal glass micromodels at same conditions. Observations showed that in the case of nanoclay concentration, the nanoparticles concentration increased the slope of recovery curve and consequently improved the final oil recovery. Also, the results of experiments illustrated that improvement of heavy oil recovery in micromodel test with nanoclay (60.6%).     

裂缝性稠油油藏蒸汽吞吐动态预测模型

在常规稠油油藏蒸汽吞吐动态预测模型的基础上,运用能量平衡理论,建立了裂缝性稠油油藏蒸汽吞吐开采动态预测模型,给出了热膨胀作用、重力驱替和毛管渗吸作用下的分析解。在求解过程中,考虑了温度对粘度、含油饱和度和油水相对渗透率的影响。该模型的实例计算结果与数值模拟计算结果相近,这表明该模型能用于裂缝性稠油油藏蒸汽吞吐动态预测。     

稠油油藏定向井双侧向测井校正方法研究

定向井由于井斜角的变化,双侧向测井数据受围岩及层厚、井眼、泥浆等环境因素影响较大,直接影响测井解释结果的准确性,在进行定向井测井解释前,需对测井曲线作校正处理。根据定向井测井特点,选择其邻近直井的标准层对定向井双侧向曲线进行校正。选择多组定向井和直井,利用最小曲率法对定向井作深度校正,选取标准层(泥岩层及致密层);由选取的标准层数据,建立定向井双侧向电阻率校正图版,对定向井双侧向电阻率进行校正处理;进行定向井校正实例分析,并对校正效果进行检验。该方法在新疆FC油田某区齐古组的定向井双侧向测井校正中得到了较好的应用效果,校正后定向井的测井解释结果更符合研究区块的储层参数特征。     

裂缝性低渗透双重孔隙介质产能动态数值模拟

低渗透油田开发与裂缝密切相关,与常规油藏相比,低渗透裂缝油藏裂缝和基质中产能动态复杂多变,如何计算、预测和分析裂缝和基质的产能动态是低渗透油田开发的重要任务。采用理论研究及数值模拟的方法,将天然裂缝表征成果应用到油藏工程研究中,提出了结合地质科学和油藏工程数据来表征和研究低渗透裂缝性油藏特征的方法,在前人研究的基础上建立了裂缝系统和基质系统的连续性方程和辅助方程,开发了预测低渗透裂缝油藏开发动态的数值模拟器,来定量研究基质-裂缝之间的流体交换和产能动态。最后利用实例对表征方法和模拟器进行了验证,这对于制定裂缝性低渗透油藏开发方案和优化油藏采收率有重要的指导作用。