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首页> 外文学位 >Transverse Relaxation in Sandstones due to the effect of Internal Field Gradients and Characterizing the pore structure of Vuggy Carbonates using NMR and Tracer analysis.
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Transverse Relaxation in Sandstones due to the effect of Internal Field Gradients and Characterizing the pore structure of Vuggy Carbonates using NMR and Tracer analysis.

机译：由于内部场梯度的影响，砂岩中的横向弛豫和使用NMR和示踪剂分析表征了Vuggy碳酸盐的孔隙结构。

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摘要

Nuclear magnetic resonance (NMR) has become an indispensable tool in petroleum industry for formation evaluation. This dissertation addresses two problems.;• We aim at developing a theory to better understand the phenomena of transverse relaxation in the presence of internal field gradients.;• Chracterizing the pore structure of vuggy carbonates.;We have developed a two dimensional model to study a system of claylined pore. We have identified three distinct relaxation regimes. The interplay of three time parameters characterize the transverse relaxation in three different regimes. In future work, useful geometric information can be extracted from from SEM images and the pore size distribution analysis of North Burbank sandstone to simulate transverse relaxation using our 2-D clay flake model and study diffusional coupling in the presence of internal field gradients.;Carbonates reservoirs exhibit complex pore structure with micropores and macropores/vugs. Vuggy pore space can be divided into separate-vugs and touching-vugs, depending on vug interconnection. Separate vugs are connected only through interparticle pore networks and do not contribute to permeability. Touching vugs are independent of rock fabric and form an interconnected pore system enhancing the permeability. Accurate characterization of pore structure of carbonate reservoirs is essential for design and implementation of enhanced oil recovery processes. However, characterizing pore structure in carbonates is a complex task due to the diverse variety of pore types seen in carbonates and extreme pore level heterogeneity. The carbonate samples which are focus of this study are very heterogeneous in pore structures. Some of the sample rocks are breccia and other samples are fractured. In order to characterize the pore size in vuggy carbonates, we use NMR along with tracer analysis. The distribution of porosity between micro and macro-porosity can be measured by NMR. However, NMR cannot predict if different sized vugs are connected or isolated. Tracer analysis is used to characterize the connectivity of the vug system and matrix. Modified version of differential capacitance model of Coats and Smith (1964) and a solution procedure developed by Baker (1975) is used to study dispersion and capacitance effects in core-samples. The model has three dimensionless groups: 1) flowing fraction (f), 2) dimensionless group for mass transfer (NM) characterizing the mass transfer between flowing and stagnant phase and 3) dimensionless group for dispersion (NK) characterizing the extent of dispersion. In order to obtain unique set of model parameters from experimental data, we have developed an algorithm which uses effluent concentration data at two different flow rates to obtain the fitted parameter for both cases simultaneously. Tracer analysis gives valuable insight on fraction of dead-end pores and dispersion and mass transfer effects at core scale. This can be used to model the flow of surfactant solution through vuggy and fractured carbonates to evaluate the loss of surfactant due to dynamic adsorption.
机译：核磁共振（NMR）已成为石油工业中评价地层不可缺少的工具。本论文解决了两个问题。•我们的目的是发展一种理论，以更好地理解存在内部场梯度的横向弛豫现象。•充实碳酸盐泡沫的孔隙结构。;我们开发了二维模型来研究粘土孔隙系统。我们已经确定了三种不同的松弛机制。三个时间参数的相互作用表征了三种不同状态下的横向松弛。在未来的工作中，可以从SEM图像和北伯班克砂岩的孔径分布分析中提取有用的几何信息，以使用我们的二维黏土薄片模型模拟横向弛豫，并在存在内部场梯度的情况下研究扩散耦合。储层表现出具有微孔和大孔/微孔的复杂孔隙结构。取决于孔洞的相互连接，孔洞的孔隙空间可分为独立的孔洞和接触孔洞。单独的孔洞仅通过粒子间的孔网络连接，并且不会增加渗透性。接触孔与岩石结构无关，并形成相互连接的孔隙系统，从而增强了渗透性。碳酸盐岩储层孔隙结构的准确表征对于增强采油工艺的设计和实施至关重要。但是，由于碳酸盐中孔隙类型的多样性和极端的孔隙水平非均质性，表征碳酸盐中的孔隙结构是一项复杂的任务。这项研究的重点是碳酸盐样品的孔隙结构非常不均一。一些样品岩石是角砾岩，而其他样品则破裂。为了表征松散碳酸盐的孔径，我们将NMR与示踪分析一起使用。微观孔隙和宏观孔隙之间的孔隙分布可以通过NMR测量。但是，NMR无法预测是否连接或隔离了不同大小的vug。示踪剂分析用于表征vug系统和矩阵的连通性。 Coats and Smith（1964）的差分电容模型的修改版本和Baker（1975）开发的求解程序用于研究核心样本中的色散和电容效应。该模型具有三个无量纲组：1）流动分数（f），2）表征流动相和停滞相之间传质的无量纲传质（NM），以及3）表征分散程度的无量纲散度（NK）。为了从实验数据中获得唯一的模型参数集，我们开发了一种算法，该算法使用两种不同流速下的废水浓度数据来同时获得两种情况的拟合参数。示踪剂分析可提供有关死角孔的比例以及岩心尺度上的分散和传质效果的宝贵见解。这可用于模拟表面活性剂溶液通过松散的碳酸盐岩和裂缝性碳酸盐的流动，以评估由于动态吸附而造成的表面活性剂损失。

著录项

  • 作者

    Rohilla, Neeraj.;

  • 作者单位

    Rice University.;

  • 授予单位 Rice University.;
  • 学科 Engineering Chemical.;Engineering Petroleum.;Petroleum Geology.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 174 p.
  • 总页数 174
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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