Two-Carrier Description of Cuprate Superconductors from NMR

Permeability, fractional porosities, irreducible water saturation and fluid viscosity calculations, derived from Nuclear Magnetic Resonance (NMR) data, are largely dependant on T2 decay rates (in NMR terminology, T2 is the time constant that characterizes the decay rate of the echo train). NMR models show that the T2 of oil is directly proportional to porosity and permeability and inversely proportional to viscosity. As oil viscosity increases, T2 decreases and the NMR signal of heavy oil may coincide with the clay bound and capillary bound water signals or even be much faster. Therefore, conventional parameters and cutoffs, used in the calculations of petrophysical properties, generally cause underestimation of porosity and permeability. By integrating core, production and conventional log data with NMR data it will be able to determine appropriate parameters and cutoffs and also generate a model to be used in the calculations of petrophysical properties from NMR data. The correct parameters, cutoffs and generated model can later be used to process NMR data from other wells where core and or production data is not available.

This study evaluates the accuracy of generating pseudo-capillary pressure curves from laboratory nuclear magnetic resonance (NMR) analysis and NMR wireline log data by comparing threshold pressures and curve characteristics to rock-derived mercury injection capillary pressure (MICP) analysis. Accurate production of pseudo-capillary pressure curves from NMR data could negate or reduce the need for expensive and rig-time-consuming core acquisition and subsequent MICP analysis. Successful application of this technique will allow production of pseudo-capillary pressure curves for large stratigraphic intervals at a significantly reduced cost and help to better constrain petroleum reserves and improve near field exploration prediction outcomes. The Tindilpie-11 well in the Cooper Basin, Australia, was used as a case study because of extensive existing conventional ore analysis and presence of an NMR wireline log covering the sampled intervals in the Permian-aged Patchawarra Formation. Six core samples underwent MICP and laboratory NMR analyses, with capillary pressure curves generated for each method. Six pseudo-capillary pressure curves were also generated from the NMR wireline log data at the coincident sample depths. The pseudo-capillary pressure curves generated from laboratory NMR data closely resemble the MICP results (mean threshold pressure error of 0.63 MPa absolute [91.4 psi]) and proved the applicability of this approach. The NMR wireline log data used is an average over a ∼1.6 m interval, which has likely led to discrepancies when compared with laboratory NMR pseudo-capillary pressure curves and MICP curves. Nonetheless, this study confirms the applicability of using laboratory NMR data to generate pseudo-capillary pressure curves that resemble MICP results. Continued development of NMR log technology and reduced logging speeds will improve the data resolution and ultimately provide high density NMR data that can be used to create pseudo-capillary pressure curves for large stratigraphic intervals at a significantly reduced cost. KEY POINTS Pseudo-capillary pressure curves derived from NMR data. Reservoir characterisation requiring minimal rock acquisition for ground truthing. Case study on the Patchawarra Formation (Cooper Basin, Australia) using SCAL data.

Partial least squares modeling of combined infrared, 1H NMR and 13C NMR spectra to predict long residue properties of crude oils

Vitrification is a cryopreservation technique increasingly applied in clinical practice for cells and tissue. This review article focuses mainly on the efficiency of vitrification of human reproductive cells and tissue, by analysing the clinical results reported in the literature. The second aspect discussed is safety of vitrification procedure. Different procedures and different types of carriers can be used, and in some cases vitrification requires a direct contact between cell/tissue/carrier and liquid nitrogen; this causes concern regarding the safety of this cryopreservation technique. Although the risk of contamination during cryopreservation remains negligible, this article explains how to overcome the hypothetical risk of contamination when using different types of vitrification carriers, in order to satisfy all existing directives.

9 - The Role of NMR in the Analysis of Chemical Libraries

Logging-While-Drilling (LWD) nuclear magnetic resonance (NMR) data was acquired in an extended reach well targeting a carbonate formation to obtain rock quality and permeability data. The challenge was to minimize lateral motion that could affect the NMR data quality. Pre-job modeling was performed to evaluate the bottom-hole-assembly (BHA) stability and optimize the drilling parameters. A novel system using downhole drilling mechanics measurements while drilling was set up to evaluate the effect of drilling mechanics on the NMR sensor while drilling. Several intervals were relogged to compare the drill pass data and the reaming data, to confirm the absence of lateral motion affecting the data. The LWD NMR data was acquired while drilling over just under 4000 ft. The well experienced a build of inclination to optimize reservoir contact. The downhole drilling mechanics flag showed a medium risk of lateral motion, also highlighting the absence of stick and slip while drilling. The LWD NMR drill pass and ream pass data compared well, confirming the absence of significant lateral motion effect on the NMR sensor while drilling. The relog passes experienced more stick and slip than the drill passes, due to the low rotations per minute (RPM) used during ream passes acquisition. The NMR highlighted a good relationship between porosity and pore size distribution in both reservoir sections. For the first time in the region, LWD NMR data is acquired in the 8.5-inch section in an extended reach well with good quality NMR data.

Machine learning in the classification of lithology using downhole NMR data of the NGHP-02 expedition in the Krishna-Godavari offshore Basin, India

A novel method for NMR data denoising based on discrete cosine transform and variable length windows

Prior to the advent of nuclear magnetic resonance (NMR) data inversion, a common approach for handling the large amount of raw echo data collected by NMR logging was data compression for improving the inversion speed. A fast compression method with a high compression ratio is required for processing NMR logging data. In this paper, we proposed a hybrid method to compress NMR data based on the window averaging (WA) and principal component analysis (PCA) methods. The proposed method was compared with the WA method and the PCA method in terms of the compression times of simulated one-, two-, and three-dimensional NMR data, the inversion times of compressed echo data, and the accuracy of NMR maps created with and without compression. We processed NMR log data and compared the inversion results with different compression methods. The results indicated that the proposed method with a high compression speed and a high compression ratio can be used for NMR data compression, and its accuracy depended on the precompressed echo number, and it is obvious that the method have practical applications for NMR data processing, especially for multi-dimensional NMR.

Considering the modern oil price environment, oil companies are more pressured than ever to reduce costs. This need affects tools used for reservoir characterization. Coring is important but expensive and is usually not available for the entire length of the well. A novel methodology is presented to perform reservoir characterization from wireline nuclear magnetic resonance (NMR) data, in the absence of any core, in offshore gas-bearing wells. This includes computing T2 cutoff, hydrocarbon saturation, permeability, and poro-fluid sand facies determination. NMR is a shallow measurement and using wireline NMR measurements is even more challenging due to higher time after bit and increased mud filtrate invasion. Consequently, its use is restricted to quantifying porosity, and even the basic assessment of bound/free fluid require correct T2 cutoff to be determined from cores. Traditional formation evaluation methods use various equations like Archie’s, dual water, Waxman Smits, etc. to determine hydrocarbon saturation, all of which have many variables which, again, must be determined from cores. This makes it imperative to have core measurements to get precise results. In this paper, we present the results of successful implementation of the proposed methodology, which functions without core data. It employs NMR data along with modern processing techniques like factor analysis and fluid substitution, and integrates density data to evaluate reservoir by 1) minimizing the mud signal, 2) using the virgin zone data to extract dominant peaks and repeated patterns on T2 distribution to divide the entire reservoir section into different poro-fluid types, 3) obtaining the T2 cutoffs for various poro-fluids facies, 4) calculating density magnetic resonance porosity (DMRP) and adopting it to drive fluid substitution, 5) obtaining original water equivalent porosity which is divided by DMRP to get water saturation, 6) employing the fluid substituted (water-only equivalent) T2 distribution along with the T2 cutoff determined by factor analysis to calculate permeability using the Timur-Coates equation.

The Natural Products Magnetic Resonance Database (NP-MRD) is a comprehensive, freely available electronic resource for the deposition, distribution, searching and retrieval of nuclear magnetic resonance (NMR) data on natural products, metabolites and other biologically derived chemicals. NMR spectroscopy has long been viewed as the ‘gold standard’ for the structure determination of novel natural products and novel metabolites. NMR is also widely used in natural product dereplication and the characterization of biofluid mixtures (metabolomics). All of these NMR applications require large collections of high quality, well-annotated, referential NMR spectra of pure compounds. Unfortunately, referential NMR spectral collections for natural products are quite limited. It is because of the critical need for dedicated, open access natural product NMR resources that the NP-MRD was funded by the National Institute of Health (NIH). Since its launch in 2020, the NP-MRD has grown quickly to become the world's largest repository for NMR data on natural products and other biological substances. It currently contains both structural and NMR data for nearly 41,000 natural product compounds from >7400 different living species. All structural, spectroscopic and descriptive data in the NP-MRD is interactively viewable, searchable and fully downloadable in multiple formats. Extensive hyperlinks to other databases of relevance are also provided. The NP-MRD also supports community deposition of NMR assignments and NMR spectra (1D and 2D) of natural products and related meta-data. The deposition system performs extensive data enrichment, automated data format conversion and spectral/assignment evaluation. Details of these database features, how they are implemented and plans for future upgrades are also provided. The NP-MRD is available at https://np-mrd.org.

The Neelam field is situated in south-east of the giant Mumbai High oilfield in western offshore basin of India. This field was discovered in 1987 and has been put under production since 1990. The field is presently under active water injection and the average oil production from the study area is approximately around 100 BOPD with 95 percent water-cut. Perforation strategy determination in a brownfield carbonate reservoir under extensive water injection is very challenging. Fluid identification is critical in these reservoirs. Wireline formation tester sampling at defined depths can be very useful for downhole fluid identification. However, the sampling is a stationary measurement and depends on successful communication with the formation fluids. Multi-dimensional nuclear magnetic resonance (NMR) data can efficiently optimize the wireline formation tester operations in such critical wells by using continuous porosity and permeability at various depths of investigations. Additionally, resistivity independent fluid typing and saturation results from NMR analysis at different depths of investigation can be used to optimize the perforation strategy. Our study established a workflow for designing an efficient completion plan and perforation strategy by integration of multi-dimensional NMR and formation tester wireline logging technologies in a single acquisition run in the Neelam field. However, the workflow is applicable to similar reservoirs elsewhere in the world. The objective was to enhance oil recovery and reduce water-cut and rig-time. NMR data were used to optimize the formation tester operations by identifying possible tight zones. Moreover, the NMR saturation profiling results provided continuous fluid typing and fluid saturations at different depths of investigations. Formation tester fluid sampling was carried out at discrete station depths in the same run after NMR acquisition; the formation tester station measurements of reservoir mobility and in-situ fluid analysis were then used to validate the continuous NMR log derived fluid characterization and permeability. Based on all this integrated workflow and timely analysis the best possible completion strategy was decided and perforation intervals were optimized. The well is presently producing around 270 BOPD with a 30 percent water-cut.

Porosity, water saturation, and net-to-gross evaluation can be challenging in thinly bedded sands. The use of standard induction resistivity for formation evaluation can lead to the overestimation of water saturation. This work explores the following options to improve formation evaluation in these conditions: the use of high resolution density and nuclear magnetic resonance (NMR) data to improve porosity vertical resolution; the use of high-resolution resistivity from an oil-based-mud microresistivity imaging tool in improving the saturation computation (Sw); and the comparison of imaging tool resistivity-based sand count and NMR-based thin-bed fraction. Using high-resolution porosity inputs from density and NMR provided a porosity curve with a better vertical resolution to match the high resolution resistivity from the imaging tool. It also identified additional productive thin beds compared to the standard resolution outputs and allowed computation of a high-resolution irreducible water saturation. The induction-based Sw is strongly affected by shoulder bed effect and overestimates Sw by approximately 10 to 15%. The high-resolution curve from the imaging tool was used as an input into the Sw computation, which was made possible by shallow oil-based mud (OBM) invasion. This approach gave good results in beds thicker than 6 in., where Sw from the imaging tool matches the irreducible water saturation computed from NMR, giving 20 to 30% Sw. A thin-bed fraction curve was computed from the NMR data. It shows a good match with the image-based high resolution- sand count and the image features, demonstrating that NMR and the imaging tool are equally able to identify and quantify thin beds, even though they have different vertical resolutions. This study showed that the microresistivity imaging tool and NMR are essential tools to characterize thinly bedded reservoirs.

Preliminary studies were made on the organic matter associated with fossil logs and uranium-rich ores of the Morrison Formation in the San Juan basin, New Mexico, using solid-state 13C nuclear magnetic resonance, stable carbon isotope ratios, and elemental analyses. These studies show that information about the structure of the organic matter can be obtained that could lead to a better understanding of its origin and nature. The nuclear magnetic resonance data indicate that the apparently non- cellular organic matter in these ores is highly aromatic, and confirm elemental analyses that show low atomic H/C ratios and high O/C ratios. Information from the nuclear magnetic resonance spectra, as well as the elemental data, led us to believe that this organic matter is more like a medium-rank coal than like the “amorphous carbon” described by previous workers. Trends in the nuclear magnetic resonance, elemental, and carbon isotope data are consistent with the hypothesis that the organic matter originated as humic acids. The trends also suggest that factors other than radiation damage could be responsible for the chemical structural nature and partially responsible for the stable carbon isotope composition of the organic matter. These factors include the early oxidation of plant material to form humic acids, which imparts structural characteristics different from those of the parent material, and the possibility that different types of plant material are involved in the formation of ores.

The difficulty of determining effective water saturations in shaly-sand oil reservoirs is an old industry problem. Zones with high water saturation may not be developed even though the resistivity logs show that hydrocarbon exist and production data indicate low water cuts. Reservoirs offshore Southwest Trinidad are examples that show a high degree of mismatch between conventional log analysis and test/production results. These shaly-sandstone reservoirs have water saturations of 50-60% and produce water-free oil or have small water cut values (<5%) based on production reports. The benefits of Nuclear Magnetic Resonance (NMR) logging data to improve shaly-sand analysis and the ability to separately predict mobile water and bound water have been demonstrated by many practitioners. However, the methods of integrating NMR data can be standalone, deterministic or statistical and the type of petrophysical outputs can vary widely. This study assesses the impact of integration methods of NMR/Open-hole data on petrophysical outputs by carrying out an extensive study on log data from five (5) wells offshore Southwest Trinidad. Methodologies for quality control of NMR data and deterministic and statistical workflows for integrating NMR and Conventional Logging data were demonstrated. An effective baseline for comparison was established by using the same environmentally corrected log data, shale/ clay parameters, water resistivity (Rw) and saturation exponents for all techniques. A Dual Water (DWM) and Wet Shale Model (WSM) workflows were developed and three sets of analyses were conducted. In the first analysis Conventional Logging data only were applied in a typical deterministic approach. In the second analysis NMR data and Conventional data were applied using a modified deterministic approach. In the third analysis NMR and Conventional log data were applied in a statistical approach via a system of simultaneous equations. All of the corresponding petrophysical outputs from these three methods of analyses were then compared with core and production data. NMR-derived total porosities were found to match core porosities regardless of shale/clay content, whereas density log porosities match only in clean reservoir sections. In shaly intervals, the Neutron-Density porosities were 5-7% higher and Density porosities were 3-5% lower than core porosities. The results from this study also show that total water saturations (Swt DWM) using NMR- derived porosities (total and bound) were similar to core data. In shaly reservoir sections, Swt-DWM and Swt-WSM using conventional logging data were 10-15% and 15-20% higher than core water saturations respectively. The integration of NMR data using a statistical approach gives the most reliable results for computing irreducible water saturations for shaly sand reservoirs with high water sturations and low water-cut. This case study illustrates how to undertake shaly-sand analysis using NMR data, including the quality control process, deterministic methods, statistical approaches and petrophysical outputs that are obtained.