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This thesis forms part of a continuing programme of research to investigate the application of NMR to fluid saturated rock. The work falls into four sections; (i) The development of a novel broad line NMR imaging technique for the study of short T2 fluid components in reservoir rock The technique is a repetitive pulse variant of an established gradient echo method which employs oscillating magnetic field gradients. The variant uses low flip angle r.f. pulses to reduce image rounding artefacts and provide naturally T1 weighted data. (ii) The selective imaging of fluids within preserved reservoir rock and the first broad line NMR imaging study of immiscible fluid flow. The selective imaging of reservoir fluids within preserved rock core samples has been achieved using T1 weighted MRI methods. To account for the natural heterogeneity of the rock and the observed mixed wettability, T1 suppression has been enhanced by lowering the temperature of the rock cores, thus exploiting the difference in dominant relaxation mechanisms of the two core fluids. A model has been developed to explain this temperature dependence in terms of pore surface relaxation theory. Fluid flow processes within reservoir rock have been investigated using chemical substitution and T1 weighted imaging. Due to the short transverse relaxation times expected at irreducible saturation, short T2 imaging protocols have been adopted and represent the first such study. This has provided quantitative data from which the individual phase saturations can be directly obtained. (iii) The first broad line NMR imaging study of liquid and vapour phase diffusion processes in partially saturated rock. Excellent agreement is found between the NMR diffusion profiles of partially saturated rock and a model based on a combination of vapour and liquid phase transport. Estimates of the surface water diffusion coefficient and vapour percolation threshold have thus been obtained. (iv) A detailed study of proton relaxation times of water-saturated rock as a function of saturation. The saturation levels range from 0.06%, equivalent to monolayer water coverage, to 100%. The results have been used to test fast diffusion relaxation theory in rock over the full saturation range for the first time. The relaxation measurements at monolayer coverage have led to the first unambiguous estimates of rock plug pore surface relaxivity. Evidence has been obtained for the effect of pore throats on the relaxation times and pore throat size estimates have been made.

The thesis entitled "Pushing the Limits of NMR Sensitivity and Chiral Analysis: Design of New NMR Methods and Bio-molecular Tools" consists of six chapters. The research work reported in this thesis is focused on the development of novel chemical and NMR methodological approaches for enantiomeric analysis and mea- surement of residual dipolar couplings (RDCs), and the development of sensitivity enhanced slice selective NMR experiments for obtaining pure shift 1H spectra and the measurement of scalar couplings. The thesis is divided into two parts. The Part I comprises chapters 2-4, where the enantiomeric analysis is discussed, which includes newly developed chiral reagents, two new weak chiral aligning media and design of novel NMR techniques. Part II comprises chapters 5 and 6, which discusses new sensitivity enhanced slice selective NMR techniques. Chapter 1 gives a general introduction to NMR and the problems investigated in the remaining chapters of the thesis. The chapter starts with a brief discussion on the introduction, advancements and general applications of NMR, discussion is also given on the NMR approaches for enantiomeric analysis both in isotropic and anisotropic phases and the measurement of RDCs, including the benefits and limitations associated with each approach. The chapter sets the tone by discussing limitations of the existed NMR enantiomeric approaches and slice-selective techniques, and builds the bridge for the rest of the chapters by addressing these limitations. The chapter also introduces slice selective experiments, their benefits over other conventional methods and limitations. Additional introductory notes are also given on some related concepts. Part I : NMR Chiral analysis and RDCs measurements Chapter 2 discusses chiral sensing properties of RNA nucleosides and their utility as chiral derivatizing agents for the enantio-discrimination of 1o-amines using one dimensional 1H NMR. A three component protocol has been proposed for the complexation of nucleosides with amines, which is rapid, economical and provides maximum diastereomeric conversion. The chiral differentiating ability of nucleosides are examined for different amines based on the 1H NMR chemical shift differences between the diastereomers (∆δ R, S ). Enantiomeric differentiation has been observed at multiple chemically distinct proton sites. It is observed that adenosine and guanosine exhibit large chiral differentiation (∆δ R, S ) due to the presence of a purine ring. The comparison of the diastereomeric excess (de) measured by NMR with those of the gravimetrically prepared ratios are in excellent agreement with each other confirming the robustness of these RNA nucleosides in discriminating primary amines. Chapter 3 establishes the smooth connectivity with the chapter 2 by discussing the limitations of the enantiomeric discrimination using NMR in isotropic solutions. This chapter discusses two new water compatible aligning media that were developed based on self-assembling strategy of small bio-molecules. The self-assembled folic acid, and the binary mixture of 50-GMP and guanosine are introduced as two novel weak aligning media. The properties of these low ordered media have been systematically studied for their easy preparation, physical parameter dependent tunability of their degree of alignment, mesosphere sustainability over a broad range of temperature and the concentration of the ingredients, and the phase reproducibility. The applications of both these new media are demonstrated for chiral and pro-chiral discrimination and also for the measurement of RDCs. Both these liquid crystalline media could be tuned to very low degree of alignment (order parameter of the order of 10−4), which provides simple first order spectra of molecules aligned in them, the analysis provide order dependent NMR spectral parameters. The 50-GMP:guanosine orienting medium can be prepared in less than 1 hour, and has been demonstrated to be an ideal medium for the determination of RDCs that are used as restraints in the structure calculations of small molecules. Chapter 4 describes 1H NMR spectral complexity in isotropic and anisotropic phases and its consequences on enantiomeric analysis. In circumventing such problems, new NMR techniques have been developed and the spin dynamics involved in the designed sequences are discussed. The newly developed 2D 1H NMR experimental method termed as RES-TOCSY, and its applicability for resolving R and S enantiomeric or diastereomeric peaks of all the coupled proton spins in isotropic phase is discussed. The utility of the developed method is demonstrated in diverse situations, such as, for suppressing impurities peaks, resolving the severely overlapped peaks and unraveling the peaks masked due to severe line broadening when metal complexes are used as chiral auxiliaries. The advantages and limitations of the method over other methods available in the literature are discussed and the significant advantage of the present method is illustrated by spectral comparison with J-resolved experiment. The appli- cation of the method for the accurate measurement of enantiomeric excess has also been demonstrated. The chapter also introduces another NMR experimental technique developed for resolving enantiomeric peaks and complete unraveling of R and S spectra in anisotropic phase. The developed 2D NMR method is cited in the literature as CH-RES-TOCSY. In addition to spectroscopic visualization of R and S spectra, the method also yields C-H RDCs. The applicability of the new experiment has been demonstrated on a chosen example. The wide utility of the method has also been demonstrated for the assignment of symmetric cis- and trans- isomers. Part II : Sensitivity Enhancement of Slice selective NMR Experiments Chapter 5 describes applications of slice selective NMR experiments over conven tional NMR methods and their limitations as far as the sensitivity of signal detection is concerned, especially in low concentrated samples. The chapter introduces the implementation of Acceleration by Sharing Adjacent Polarization (ASAP) technique in slice selective experiments. It is convincingly demonstrated that ASAP helps in reducing inter scan relaxation delay and consequently permits acquisition of more number of scans in a given time, resulting in the gain in signal enhancement by a factor of two. The pulse sequences have been suitably designed for obtaining the pure shift 1H spectra and in G-SERF experiment for the measurement of 1H-1H couplings, both with significantly enhanced signal intensities. Chapter 6 describes new sensitivity enhanced slice selective NMR methods for mea- surement of scalar couplings. A new experiment has been developed which is named as Quick G-SERF (QG-SERF). It is a 1D NMR slice selective method developed based on real time spin manipulation technique. The method gives multiple scalar couplings of a selected spin with simplified multiplets, which is analogous to the 2D G-SERF but with considerable saving in instrument time by 1-2 orders of magnitude. The rapidness of the experiment arises due to reduced dimensionality. The spin dynamics involved in the pulse sequence and its working principle have been described. The application of the method is illustrated for the measurement of 1H-1H couplings. The sequence has been further improved to obtain the heteronuclear couplings between two abundant spins in an orchestrated manner and has been demonstrated for measurement of 1H-19F couplings. This sequence cited as HF-QG-SERF has been implemented on the molecules containing number of chemically non-equivalent fluorine atoms.