Functional group resolved NMR relaxation of 3-carbon adsorbates in mesoporous alumina

NMR relaxation analysis provides a unique and non-invasive probe of fluid dynamics within porous materials,and may be applied to the interpretation of a wide variety of material and interfacial characteristics.Here,we report two-dimensional^(1)H T_(1)-T_(2)relaxation correlation measurements of a range of three-carbon adsorbates(1-propanol,2-propanol and propanoic acid)imbibed within the mesoporous metal oxide gamma-alumina.Our data,acquired across field strengths of 2 MHz,12.7 MHz and 43 MHz,clearly reveal two populations in each measurement,identified as the alkyl and hydroxyl moieties of each adsorbate.These results expand the range of materials in which such functional group resolved relaxation is known to occur,and demonstrate the clear persistence of such phenomena using a range of typical benchtop NMR systems employed to study fluid-saturated porous media.

Binary fluids in mesoporous materials: Phase separation studied by NMR relaxation and diffusion

Relaxation and diffusion measurements were carried out on single and binary liquids filling the pore space of controlled porous glass Vycor with an average pore size of about 4 nm.The dispersion of the longitudinal relaxation time Tr is discussed as a means to identify liquid-surface interaction based on existing models developed for metal-free glass surfaces.In addition,the change of T1 and T2 with respect to their bulk values is discussed,in particular T2 serves as a probe for the strength of molecular interactions.As the native glass surface is polar and contains a large amount of hydroxyl groups,a pronounced interaction of polar and protic adsorbate liquids is expected;however,the T dispersion,and the corresponding reduction of T2,are also observed for non-polar liquids such as alkanes and cyclohexane.Deuterated liquids are employed for simplifying data analysis in binary systems,but also for separating the respective contributions of intra-and intermolecular interactions to the overall relaxation rate.Despite the lack of paramagnetic impurities in the glass material,H and 2H relaxation dispersions of equivalent molecules are frequently found to differ from each other,suggesting intermolecular relaxation mechanisms for the'H nuclei.The variation of the T dispersion when comparing single and binary systems gives clear evidence for the preferential adsorption of one of the two liquids,suggesting complete phase separation in several cases.Measurement of the apparent tortuosity by self-diffusion experiments supports the concept of a local variation of sample composition within the porespace.

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.

NMR弛豫方法测定储油岩芯的有效渗透率

在对储油岩芯液体吸附特性研究的基础上 ,提出了用核磁共振弛豫方法测定岩芯有效渗透率的方法 ,并对实际样品进行了测定分析 ,获得了较满意的结果 .测定的有效渗透率较传统方法测定的结果更接近于实际的储油岩层的渗透率 .有效渗透率的值可以用来进行油藏注水开发效果分析 。

Radicals on the silica surface:probes for studying dynamics by means of fast field cycling relaxometry and dynamic nuclear polarization

Determining the dynamics of adsorbed liquids on nanoporous materials is crucial for a detailed understanding of interactions and processes on the solid-liquid interface in many materials and porous systems.Knowledge of the influence of the presence of paramagnetic species on the surface or within the porous matrices is essential for fundamental studies and industrial processes such as catalysts.Magnetic resonance methods,such as electron paramagnetic resonance(EPR),nuclear magnetic resonance(NMR)and dynamic nuclear polarization(DNP),are powerful tools to address these questions and to quantify dy-namics,electron-nuclear interaction features and their relation to the physical-chemical parameters of the system.This paper presents an NMR study of the dynamics of polar and nonpolar adsorbed liquids,represented by water,n-decane,deuterated water and nonane-d20,on the native silica surface as well as silica modified with vanadyl porphyrins.The analysis of the frequency dependence of the nuclear spin-lattice relaxation time is carried out by separating the intra-and intermolecular contributions,which were analyzed using reorientations mediated by translational displacements(RMTD)and force-free-hard-sphere(FFHS)models,respectively.

岩心孔隙介质中流体的核磁共振弛豫

弛豫时间是核磁共振研究中的一个重要参数,岩心孔隙介质流体的弛豫过程是自由流体弛豫机制、表面弛豫机制和流体的扩散弛豫机制共同作用的结果,它包含了丰富的孔隙和流体本身的信息.弛豫时间和自扩散系数的测量及对弛豫时间的分析是核磁共振技术应用于岩心分析和石油勘测的重要内容.

多孔岩心的渗透性

The relaxation properties of water saturated in porous core are discussed and the dis-tribution of proton transverse relaxation time and bi-exponential model of longitudiual relaxationtime are obtained, which provide an illustration for two-model of fluids saturated in porous media.The cutoff value of T1 based ou relaxation specific property of fluids in porous core is adopted toimprove the correlation between permeability

低渗储层可动流体核磁共振研究

以低磁场核磁共振岩心分析技术为主,辅助以岩石薄片、环境电镜扫描、高分辨率CT、成像测井等常规测试手段,对国内3种不同岩性的典型低渗储层共计277块基质岩样进行可动流体评价研究,分析储层可动流体分布规律和影响因素,计算可动流体的T2截止值和孔喉半径下限值。研究表明:低渗储层可动流体参数变化范围较宽;岩样渗透率越高,其与可动流体参数的相关性越强;低渗透砂岩储层可动流体百分数与孔隙度、渗透率之间相关性均较好,利用非线性最优化方法得到的计算值与实测值吻合很好;微裂缝的发育程度、孔径分布、粘土矿物含量及其充填程度等微观孔隙结构特征是低渗储层可动流体的主要影响因素。

核磁共振弛豫方法测定砂岩有效渗透率

在对储油岩芯液体吸附特性研究的基础上 ,提出了用核磁共振弛豫方法测定岩芯“有效渗透率”的方法 ,并对实际样品进行了测定分析 ,获得了较满意的结果 .此方法测定的有效渗透率较传统方法测定的渗透率更接近于实际的储油岩层的渗透率 .有效渗透率的值可以用来进行油藏注水开发效果分析 ,研究油层剩余油分布 .

多孔介质内流体流动的格子Boltzmann模拟

采用格子Boltzmann方法模拟多孔介质内的流动过程,通过预测渗透率,比较了单松弛模型、多松弛模型和熵格子模型在多孔介质计算中的优劣,为研究多松弛模型中各自由参数的影响,选择了12种组合进行模拟,此外,还将大涡模拟与格子Boltzmann方法相结合模拟了多孔介质内高Reynolds数下的流动及流型的转变。结果表明:单松弛模型和熵格子模型预测的渗透率随黏度逐渐增大,而多松弛模型得到的结果随黏度变化很小,另外,多松弛模型中不同松弛参数的组合对结果有较大的影响,通过比较推荐了模拟多孔介质时的最佳组合,计算结果与经验公式吻合较好。大涡模拟与多松弛模型结合较好地预测了多孔介质内流型的转变,Reynolds数越大,多孔介质内的涡越多,并且变大。

快速孔渗核磁共振测井模式设计

为增强现有核磁共振测井仪器的纵向分辨率、提高测井速度,在常规CPMG测量序列的基础上,提出改进型FCPMG序列。对该序列的理论分析和工程软件建模仿真得出,在2 MHz的核磁共振岩心分析系统上进行测试实验,结果与理论仿真完全吻合。首次提出采用该序列高分辨率快速测量孔渗模型。通过饱和水的岩心测试分析,得出孔隙模式下,该测量模式能够快速测量,获得高精度、高纵向分辨率的测量结果。

核磁共振技术在煤层气勘探中的应用

为了解决低孔低渗煤储层的孔隙度、饱和度数据测定和渗透率计算,克服常规实验中取心困难的问题,使用核磁共振技术、利用H核弛豫时间的规律性变化,通过对煤样进行不同饱和状态下的测试,测定煤样中可动流体、束缚流体等参数,得出了低孔低渗煤储层的孔隙度、渗透率数据,为煤层气勘探提供有效的孔隙度、渗透率数据,对煤层气的排采、开发具有重要意义。同时,数据表明:煤储层中,孔隙度、可动流体饱和度越大,渗透率越高。

微型核磁共振探头在岩石孔内测量可行性研究

采用微型核磁共振探头在井壁中钻孔定点测量与核磁共振测井仪器在井眼中测量相比,具有纵向分辨率高、探测深度大等优势;与传统实验室在地面测量相比,具有环境真实、应用见效快的优点。但微型核磁共振探头研究尚处于起步阶段,在岩石多孔介质中测量的可行性有待验证。研究利用一种圆柱形微型核磁共振探头,在不同孔隙度的岩石孔内进行了测试,并与实验室测量结果对比。结果显示,微型核磁共振探头测量岩石的T2信号幅度与岩石孔隙度线性呈正相关;在中高孔隙岩石中微型核磁共振探头与实验室测量结果具有一致性,在低孔隙岩石中微型核磁共振探头测量结果信噪比较差。认为微型核磁共振探头虽然对致密岩石测量效果欠佳,但在中高孔隙岩石中能够反映孔隙度和孔隙结构信息。

低场核磁法测定凝胶过滤介质的孔径分布

凝胶过滤介质在蛋白质、多糖等生物大分子的分离纯化过程中具有非常重要的作用,其中介质的孔径分布是决定分离纯化效果的关键因素。由于绝大部分凝胶过滤介质是软凝胶,因此很难用常规的方法如压汞法、低温氮吸附法等测定其孔径分布。本文探索了利用低场核磁共振测定凝胶过滤介质的孔径分布的方法。首先通过抽滤、自制琼脂糖凝胶块等实验确定了峰的归属,明确了介质孔内水、介质间隙水和自由水在核磁共振横向弛豫时间(T2)图谱上的分布范围;随后与逆体积排阻层析法(ISEC)测定的结果相对比,得出层析介质孔径和介质孔内水弛豫时间的关系;最后通过高斯正态拟合得到了介质的孔径分布。实验结果证实了低场核磁共振法测定凝胶过滤介质孔径分布的可行性。该法操作简单、测定迅速,并可以为其他层析介质孔径分布的测定提供参考。

多孔介质水合物中未水合水的核磁共振实验研究

利用低场核磁共振技术开展多孔介质水合物中未水合水研究,提出一种定量分析含水合物的多孔介质未水合水含量的实验方法。研究结果表明:颗粒粒径越小,未水合水含量较高;当颗粒粒径相同时,初始含水量越高未水合水含量也越高;初始压力越低,未水合水含量越高;未水合水含量较高时多分布于较大孔隙和大孔隙中,未水合水含量较低时多分布于小孔隙和较大孔隙中。在水合物形成过程中,颗粒粒径、初始含水量及初始压力均对水分的迁移有一定影响,最终影响未水合水的含量及孔隙分布变化。

西湖凹陷低渗砂岩气藏可动水饱和度研究

通过对西湖凹陷22块岩心进行核磁共振实验,确定了本区域可动水饱和度的分布规律,并获得了不同低渗岩样气相渗透率与束缚水饱和度关系曲线。西湖凹陷低孔渗储层的物性好,但可动水饱和度高,这是造成本区气藏产能低的主要原因。通过气田实际生产实例,验证了低孔渗气藏产水的可能性,为该类气藏的开发提供指导。