Visualization of CO_2 and oil immiscible and miscible flow processes in porous media using NMR micro-imaging

CO2 flooding is considered not only one of the most effective enhanced oil recovery （EOR） methods, but also an important alternative for geological CO2 storage. In this paper, the visualization of CO2 flooding was studied using a 400 MHz NMR micro-imaging system. For gaseous CO2 immiscible displacement, it was found that CO2 channeling or fingering occurred due to the difference of fluid viscosity and density. Thus, the sweep efficiency was small and the final residual oil saturation was 53.1%. For supercritical CO2 miscible displacement, the results showed that piston-like displacement occurred, viscous fingering and the gravity override caused by the low viscosity and density of the gas was effectively restrained, and the velocity of CO2 front was uniform. The sweep efficiency was so high that the final residual oil saturation was 33.9%, which indicated CO2 miscible displacement could enhance oil recovery more than CO2 immiscible displacement. In addition, the average velocity of CO2 front was evaluated through analyzing the oil saturation profile. A special core analysis method has been applied to in-situ oil saturation data to directly evaluate the local Darcy phase velocities and capillary dispersion rate.

The Effect of Media on Biomass and Oil Production in Botryococcus braunii Strains Kossou-4 and Overjuyo-3

The green algae Botryococcus braunii is widely recognized as a source of oil, including hydrocarbons. However, the slow rate of growth B. braunii hampers its commercial development. This stu- dy addresses this by examining the effects of three growth media on biomass and oil production in two B. braunii Race B strains, Kossou-4 and Overjuyo-3. Growth of B. braunii strains in BG11 medium resulted in significantly higher growth (2.3 - 4.2 and 2.9 - 6.0 fold increases in Kossou-4 and Overjuyo-3 respectively) compared to the JM and BBM-3N media after 15 days. A similar trend was obtained when biomass was measured indirectly using optical density (OD) and chlorophyll fluo-rescence. Oil production was also significantly higher in BG11 whether measured as oil weight or absorbance (ODs at 680 and 750 nm). However, the presence of extracellular oil was shown to in-crease absorbance values making OD measurements less reliable than dry weight assays. Maximum recovery of oil was recorded when hexane was used as solvent compared to hexane-isopro- panol and heptane. These results suggest that BG11 is the best growth medium for these two strains under the conditions of this experiment.

Features and imbibition mechanisms of Winsor Ⅰ type surfactant solution in oil-wet porous media

The relationship between NaCl concentration and the phase change behavior of microemulsion of anionic surfactant was characterized by the salinity scan experiments.The wettability of WinsorⅠtype surfactant solution(WⅠsolution)and the effect of NaCL concentration on phase change behavior of WⅠsolution and imbibition in oil-wet porous media were investigated by microfluidic experiments in this study.The WⅠsolution and WinsorⅠtype microemulsion are similar in wetting phase with stronger wettability than other phases.Two main mechanisms of WⅠsolution enhancing imbibitions recovery in oil wet porous media are the wetting phase drive and residual oil solubilization.Under the salinity condition of WinsorⅠtype microemulsion,the NaCl concentration has strong impact on the imbibition mechanism of WⅠsolution,the higher the NaCl concentration,the complex the imbibition process and the higher the imbibition efficiency will be.The NaCl concentration has strong impact on the solubilization ability to oil of the WⅠsolution,the higher the NaCl concentration,the stronger the solubility of the WⅠsolution to residual oil will be.

Fracture prediction approach for oil-bearing reservoirs based on AVAZ attributes in an orthorhombic medium

Fracture systems in nature are complicated. Normally vertical fractures develop in an isotropic background. However, the presence of horizontal fine layering or horizontal fractures in reservoirs makes the vertical fractures develop in a VTI（a transversely isotropic media with a vertical symmetry axis） background. In this case, reservoirs can be described better by using an orthorhombic medium instead of a traditional HTI（a transversely isotropic media with a horizontal symmetry axis） medium. In this paper, we focus on the fracture prediction study within an orthorhombic medium for oil-bearing reservoirs. Firstly, we simplify the reflection coefficient approximation in an orthorhombic medium. Secondly, the impact of horizontal fracturing on the reflection coefficient approximation is analyzed theoretically. Then based on that approximation, we compare and analyze the relative impact of vertical fracturing, horizontal fracturing and fluid indicative factor on traditional ellipse fitting results and the scaled B attributes. We find that scaled B attributes are more sensitive to vertical fractures, so scaled B attributes are proposed to predict vertical fractures. Finally, a test is developed to predict the fracture development intensity of an oil-bearing reservoir. The fracture development observed in cores is used to validate the study method. The findings of both theoretical analyses and practical application reveal that compared with traditional methods, this new approach has improved the prediction of fracture development intensity in oil-bearing reservoirs.

Stability and water control of nitrogen foam in bulk phase and porous media

Foam is widely used in the petroleum industry thanks to its unique properties and performance. Its application to water control in oil wells has received more and more attention. The stability of nitrogen foam was investigated in pressurized equipment and sand pack. The result indicated that with increasing pressure （0-2 MPa） the stability of foam in the pressurized equipment increased linearly. Increased nitrogen injection pressure caused better dispersion of nitrogen-foaming solution in porous media. The initial residual resistance factor to gas was an exponential function of injection pressure, but the residual resistance factor （to gas and liquid） decreased exponentially with time. The halflife of foam in porous media （expressed in residual resistance factor） was much longer than that in bulk phase （expressed in foam height）. Pore model analysis indicated that good dispersion in porous media and the presence of thick liquid film during dispersion were the main reasons for high stability. Field test indicated that effective residence of foam in the formation not only resulted in much better heat insulation, but also improved steam stimulation by enhancing steam heating.

Application of control volume based finite element method for solving the black-oil fluid equations

This is the second paper of a series where we introduce a control volume based finite element method （CVFEM） to simulate multiphase flow in porous media. This is a fully conservative method able to deal with unstructured grids which can be used for representing any complexity of reservoir geometry and its geological objects in an accurate and efficient manner. In order to deal with the inherent heterogeneity of the reservoirs, all operations related to discretization are performed at the element level in a manner similar to classical finite element method （FEM）. Moreover, the proposed method can effectively reduce the so-called grid orientation effects. In the first paper of this series, we presented this method and its application for incompressible and immiscible two-phase flow simulation in homogeneous and heterogeneous porous media. In this paper, we evaluate the capability of the method in the solution of highly nonlinear and coupled partial differential equations by simulating hydrocarbon reservoirs using the black-oil model. Furthermore, the effect of grid orientation is investigated by simulating a benchmark waterflooding problem. The numerical results show that the formulation presented here is efficient and accurate for solving the bubble point and three-phase coning problems.

Displacement of Oil in a Porous Medium on Diphasic Flow by Water Injection

The purpose of this article is to show the role and influence of fluid injection, porosity on two-phase flows in porous media for the purpose of improving and increasing recovery efficiency assisted by oil. An experimental study was carried out in porous media, it is a plexiglass cylinder filled with sands saturated with crude oil. Pressure drop and data processing for two-phase flow are measured and processed using a differential pressure sensor connected to an acquisition computer. It thus makes it possible to determine the pressure difference between the inlet and the outlet of the porous medium over time. In this experiment, the flow rates at the inlet and the outlet of the porous medium were measured as a function of time using a flow rate and a pump. To describe these flows we will use Darcy’s model.

Influence of the Chemical Composition of Completion Fluids on the Propagation of Electromagnetic Waves within Oil Wells

The propagation of electromagnetic waves in the annular region of oil wells was studied. The present study aims to analyse the propagation attenuation along the well, as well as the input impedance determined by a source placed near the wellhead. A coaxial waveguide model was adopted with heterogeneous dielectrics and losses. First, a wave equation solution for the waveguide is presented, assuming a homogeneous medium with losses, by solving the equation in cylindrical coordinates using the vector potential technique. An uncertainty analysis model is then developed to model the heterogeneous characteristics of the medium. Monte Carlo simulations were performed with the created model using data gathered from the literature. The results of the simulations indicate that propagation in the transverse electromagnetic mode has the smallest attenuation and that for depths of up to 4000 m, there is an attenuation of less than 52 dB. Furthermore, the input impedance ranges from 10 Ω to 10 kΩ because of the uncertainties involved in the problem in question.

新传播媒介下的中国油画色彩的衍变——高明度、高纯度的流行化趋势

油画在中国发展的不同阶段所产生的色彩演变反映了时代进步、技术发展的特征。现今,当全民进入移动网络时代,观看方式和艺术作品的展示方式愈加向屏幕端集中,中国油画色彩高明度、高纯度的流行趋势显现出来。这种趋向与流行文化是共生共存的关系,流行文化一直以来对油画艺术与人们的视觉习惯影响巨大,当下这种影响则更为显著。

油画语言在新媒介艺术绘画中的研学和应用

新艺术媒介通过科学技术将艺术思想付诸于视觉画面,传统的油画艺术面临了前所未有的挑战。文章重新思考传统的油画艺术,探讨油画语言在新媒介艺术绘画中的应用及其重要性。

基于多孔介质理论的35kV油浸式变压器热点简化计算

低电压等级的油浸式变压器绕组往往由漆包圆线绕制而成,其温升及热点的准确计算需要考虑漆包圆线间的缝隙对油流及温升的影响,而精细建模时建模工作量和数值计算量都非常大。针对这一问题,提出将多孔介质理论应用于油浸式变压器简化建模的思路。首先验证了多孔介质理论应用于油浸式变压器热点计算的有效性。其次,基于多孔介质理论建立35 kV油浸式变压器绕组的简化模型,采用Fluent软件计算出其温升热点分布。最后将变压器的多孔介质理论简化模型所得的仿真结果与光纤测量结果进行对比。结果表明仿真与实验的热点温度误差在4℃以内,热点位置与实验结果保持一致,验证了多孔介质理论简化模型计算方法的准确性。多孔介质理论的应用为大规模变压器3维流-热耦合提供了新的计算思路,有助于工程实际中变压器热点温度的简化计算。

疏松砂岩稠油油藏防砂介质的原油-地层砂协同复合堵塞机制与规律

针对稠油出砂井防砂介质堵塞问题,使用稠油与水混合液携带地层砂,开展单向驱替流动、热采交变吞吐流动两种模式下的挡砂堵塞驱替模拟试验,揭示不同条件下割缝、绕丝、复合滤网和砾石层等多类型防砂介质的稠油-地层砂协同堵塞机制与规律,根据堵塞机制和定量关系,构建稠油-地层砂对防砂介质堵塞程度和动态产能预测模型。结果表明:高黏度稠油对防砂层多孔介质具有明显堵塞作用,渗透率损伤可高达70%;稠油防砂井中,存在稠油和地层砂对防砂介质的协同堵塞机制,稠油以束缚油的形式占据介质空间,加剧内部分选桥架堵塞,最终造成90%以上渗透率损害,但同时挡砂效果得到提升;热采蒸汽交变吞吐生产方式对稠油-地层砂的协同堵塞具有明显的解除堵塞效应;但随着交替轮次的增加,解堵和渗透率恢复幅度逐渐下降;对于稠油油藏防砂,建议挡砂精度相比常规油藏防砂精度放宽1~2个等级。

制油技术和储藏条件对高油酸花生油品质的影响

为更好地把控花生油的品质和安全,研究了不同炒制温度(132、137、142℃)、过滤介质(厚布/薄布/滤纸板、花生饼层/厚布/薄布、助滤剂/厚布/薄布、厚布/薄布)、储藏条件(室内储藏、室外储藏)对高油酸花生油品质的影响。结果表明:选择炒制温度为137℃,采用花生饼层/厚布/薄布作为过滤介质,能够获得风味与品质俱佳的高油酸花生油,且这种优化能够降低生产成本,为企业节约资源;随着储藏时间的延长和温度的升高,普通花生油和高油酸花生油的酸值和过氧化值均逐渐升高,且酸值变化较小,过氧化值变化显著,在25℃室内储藏182 d时,普通花生油和高油酸花生油的过氧化值涨幅分别为398%和77%,而在45℃室内储藏182 d时,2种花生油过氧化值的涨幅分别为927%、271%;在室外储藏45 d,未包裹瓦楞纸的普通花生油与高油酸花生油的过氧化值涨幅分别为582%和87%,经过瓦楞纸包裹处理后,2种花生油的过氧化值涨幅分别为116%、19%。综上,在不同储藏条件下,高油酸花生油均展现出较好的储藏稳定性,且低温、使用瓦楞纸进行包裹更有利于其储藏。

低温高雷诺数下摩擦阻力测量及多孔介质减阻研究

为研究低温高雷诺数条件下多孔介质湍流减阻规律及雷诺数效应,在0.3 m低温连续式风洞开展了壁面摩擦阻力测量及多孔介质减阻试验。分别在光滑平板和多孔介质区域下游布置低温脉动压力传感器和油流,对脉动压力功率谱及下游全局摩擦阻力进行测量。结果表明:摩擦阻力系数随雷诺数的增大而减小;多孔介质减阻率随雷诺数的增大(增大马赫数或降低来流总温),呈无固定规律下降趋势,且多孔介质的引入,使下游脉动压力的低频信号强度增加,高频信号强度减弱;在马赫数Ma=0.300、雷诺数Re=7.51×10^(6)、来流总温T_(0)=140 K这一典型工况下,多孔介质仍具有11.4%的减阻率,初步验证了在低温高雷诺数条件下使用多孔介质减阻控制策略的可行性。

多孔介质中油包水乳状液流动规律及液阻效应

含有胶质和沥青质等天然活性物质的原油在喉道剪切作用下易和水相形成油包水乳状液,产生液阻效应,堵塞地层导致油井产量急剧降低。利用室内岩心驱替实验和微观孔隙流动模拟技术,研究了原油黏度、含水率、乳状液粒径与喉道直径比等因素影响下,油包水乳状液在复杂多孔介质内的流动规律和液阻效应。结果表明,随含水率增加,油包水乳状液的液阻效应增强,导致启动压力梯度增加。当原油黏度为550 mPa·s、乳状液含水率为20%~50%、岩心渗透率为300×10^(-3)μm^(2)时,油包水乳状液的启动压力梯度为12~37 MPa/m。原油黏度对高黏油(550 mPa·s)乳状液启动压力梯度的影响更大,乳状液粒径与喉道尺寸的匹配程度对低黏油(<30 mPa·s)乳状液启动压力梯度的影响更显著。由于液阻效应,水滴在喉道入口处聚集并发生聚并,使油包水乳状液中水滴粒径变大。油包水乳状液粒径与喉道直径比值越大,分散相(水滴)通过喉道时的渗流阻力越大。油包水乳状液的毛细管数越小,液阻效应导致渗流阻力的增加倍数越大。计算表明,当毛细管数为9.9×10^(-4)(低黏油)、乳滴粒径与喉道直径比为2.5或10.0时,液阻效应导致油包水乳状液通过喉道时的渗流阻力增加到孔隙中流动渗流阻力的7倍或35倍。研究结果明确了油包水乳状液在多孔介质中流动的液阻效应及其影响因素,为地层原油渗流和提高原油采收率研究提供理论指导。

结构无序性对多孔介质中CO_(2)驱指进及提采的影响

在CO_(2)非混相驱替过程中,指进的发生显著降低采收率.已有研究主要关注驱替条件及流体物性等对指进的影响,而多孔介质非均质性的影响仅局限于润湿性的作用,储层孔隙的结构无序性对指进模式的调控及提采机制仍有待探究.本文提出了定量描述多孔介质无序性的无量纲参数——偏移度,建立了无序多孔介质模型,采用相场法追踪相界面演变,研究CO_(2)驱中偏移度及驱替压力对指进的影响.结果发现,偏移度增大时促进指进的形成,导致残余油饱和度升高.在不同的注入压力下,获得了两种典型的流动模式:指进和稳定驱替.随着偏移度的增加,从指进转变到稳定驱替所需要的临界压力逐渐增大.且随着注入压力的增大,不同偏移度下突破时刻的残余油饱和度均下降,但同一压力下,偏移度越高,残余油饱和度越大.这将有助于我们了解不同储层结构中CO_(2)驱替前沿运移规律,对提高原油采收率具有指导意义.

非均质土壤多孔介质中泄漏原油扩散特性分析

探究埋地管道泄漏原油在非均质多孔介质中扩散特性,对准确预测埋地管道原油泄漏位置、应急修复处理以及降低输油管道泄漏事故危害性有着重要意义。建立埋地输油管道在非均质多孔介质中的泄漏模型,基于计算流体力学方法针对特定变量条件下多孔介质多相渗流开展数值模拟;研究不同回填土孔隙率、泄漏速度对原油扩散特性的影响及原油扩散后非均质多孔介质温度场的变化规律。研究结果表明:无论回填土孔隙率如何,原油泄漏过程均包含加速阶段、过渡阶段、稳定阶段;当泄漏原油体积流量一定时,回填土孔隙率越小、泄漏速率越大,扩散速率越快,其在空气中的扩散效率就越高,反之亦然;泄漏后土壤多孔介质温度场对回填土孔隙率变化并不敏感,泄漏速率是主导温度场变化的主要因素。

多孔介质中乳状液驱油的两相流动过程及其影响因素

了解乳状液在多孔介质中的驱油过程及其机理,是发展乳状液驱油技术应用的基础。搭建了微流体可视化实验平台,揭示了多孔介质中乳状液驱油过程的两相流动过程及其影响因素。结果表明,水和表面活性剂的驱替模式均为黏性指进,使用乳状液驱油会产生液滴堵塞效应,能有效抑制黏性指进,增强界面稳定性,提高驱替效率。分析了毛细管数、油相-驱替相黏度比和液滴-孔隙尺寸比对乳状液驱油的影响,并通过建立基于不同毛细管数与黏度比下的驱替模式分布相图,得到了多孔介质中乳状液稳定驱替和黏性指进两种驱替模式的转变界限,证明乳状液驱对比水驱提高了黏性指进出现的临界毛细管数和黏度比,有效提高了驱替稳定性和驱替效率,为利用乳状液进行实际原油开采提供了理论基础。

新技术与媒介的应用——油画语言介入当代陶瓷绘画探讨

新技术和媒介在陶瓷绘画中的应用,能够增强画面表现力和艺术创新性,提供更多样化的视觉效果。新技术的引入还为陶瓷绘画带来了更广阔的创作空间和表现手段,对于促进当代陶瓷绘画的发展和创新具有重要意义,并为当代陶瓷艺术创作提供了参考和启示。