scholarly journals Review of NMR Studies for Oilwell Cements and Their Importance

2021 ◽  
Vol 5 (2) ◽  
pp. 18
Author(s):  
Fatemeh K. Saleh ◽  
Catalin Teodoriu ◽  
Carl Sondergeld
Keyword(s):  
Relaxation Times ◽  
Experimental Studies ◽  
Operating Characteristics ◽  
T2 Relaxation ◽  
Nmr Studies ◽  
Cement Pastes ◽  
Curing Conditions ◽  
Work Related ◽  
Data Comparison ◽  
Water Response

This paper summarizes experimental studies using Nuclear Magnetic Resonance (NMR) to evaluate cement porosity, pore size distribution, and other characteristics such as Calcium Silicate Hydrate (CSH) gel structure and morphology. The first known paper on NMR experiments to investigate cement pastes was published in 1978. Two main NMR parameters, the so-called longitudinal T1 and transverse T2 relaxation times, are commonly measured and analyzed, representing the water response which is trapped in the cement. The hydration process reported in this paper was found to be monitored from as low as 10 min to longer than 365 days. Other studies conducted experiments by using NMR, especially during the 1980s. These studies employed variations in methodologies and frequencies, making data comparison difficult. Additionally, different spectrometers and NMR concepts, as well as operating characteristics, were used. Therefore, it is challenging to reconcile results from previous NMR studies on cement. Other significant hurdles are different cement types, water/cement ratio, and curing conditions. One notable observation is that there has not been any comprehensive laboratory work related to NMR on oilfield cement types, including porosity and hydration. Two recent studies have presented NMR measurements on class G and class H cements.

Cardiac Magnetic Resonance Quantitative Tissue Markers in the Clinical Application Value for the Diagnosis of Acute Myocarditis

2018 ◽  
Vol 8 (9) ◽  
pp. 1751-1756 ◽  
Author(s):  
Liu Gang ◽  
Zeng Mu ◽  
Ma Zenglin ◽  
Liu Jiayi ◽  
Fan Zhanming ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Diagnostic Performance ◽  
Acute Myocarditis ◽  
Relaxation Times ◽  
Mapping Technique ◽  
Operating Characteristics ◽  
T2 Relaxation ◽  
Gadolinium Enhancement

Objectives: To determine the value of cardiac magnetic resonance (CMR) quantitative tissue markers in the diagnosis of acute myocarditis, compared with the traditional Lake-Louise criteria (LLC). Methods: Totally 35 cases of patients diagnosed as acute myocarditis in Beijing Anzhen Hospital and 35 healthy volunteers were enrolled in our study, from May 2014 to August 2016. CMR protocol included quantitative assessment of T1 relaxation times using modified Look-Locker inversion recovery (MOLLI), extracellular volume fraction (ECV), T2 relaxation times. Established Lake-Louise criteria (LLC) consisting of T2-weighted signal intensity ratio (T2-ratio), early gadolinium enhancement ratio (EGEr), and late gadolinium enhancement (LGE) were assessed. Receiver operating characteristics analysis was performed to compare diagnostic performance. Results: T2-ratio (1.85±0.21 vs. 1.58±0.15; P = 0.002) and EGEr (3.87±1.62 vs. 2.15±1.36; P =0.024) were significantly higher in myocarditis subjects than in control subjects. Non-ischemic LGE was found in 27/35 (77.1%) of all myocarditis patients. Regional myocardial edema was found in 23/35 (65.7%) of all myocarditis patients. Myocardial T1 and T2 relaxation times and ECV were significantly prolonged in the myocarditis group compared with the control group (T1 native relaxation time: 1310±62 vs. 1247±27 ms, T2 native relaxation time: 65.46±8.49 vs. 55.17±3.59 ms; ECV: 34.47±8.52 vs. 27.68±5.82, P < 0.001, respectively). Areas under the curve of native T1 (0.94) and T2 relaxation times (0.91) were higher compared with those of the other CMR parameters (T2-ratio: 0.73, EGEr: 0.72, LGE: 0.88, LLC: 0.90, ECV: 0.79). Combined with LGE, each native mapping technique outperformed the diagnostic performance of LLC (P < 0.01, respectively). A combination of native parameters (T1, T2 relaxation times) significantly increased the diagnostic performance of CMR compared with LLC without need of contrast media application (0.99 vs. 0.90; P < 0.05). Conclusion: CMR quantitative tissue markers has good diagnostic efficiency for acute myocarditis, it may be potential to replace the Lake-Louise criteria in the future in patients with contraindications for the use of gadolinium-based contrast agents.

scholarly journals Определение времени продольной релаксации текущей жидкости ядерно-магнитным спектрометром дифференциального типа

2020 ◽  
Vol 46 (22) ◽  
pp. 46
Author(s):  
В.В. Давыдов ◽  
Н.С. Мязин ◽  
В.И. Дудкин ◽  
Р.В. Давыдов
Keyword(s):  
Flow Rate ◽  
Simultaneous Measurement ◽  
Entire Range ◽  
Relaxation Times ◽  
Experimental Studies ◽  
The State ◽  
Magnetic Spectrometer ◽  
New Method ◽  
T2 Relaxation ◽  
Flowing Liquid

The necessity of simultaneous measurement of the longitudinal T1 and transverse T2 relaxation times for monitoring the state of the flowing liquid during the study in the range of flow rate q changes by at least two orders of magnitude has been substantiated. A new method for measuring T1 has been developed. For its implementation, the design of a differential nuclear magnetic spectrometer has been proposed, which makes it possible to measure T1 in the entire range of measurement of flow rate q. The results of experimental studies are presented.

Quantification of T1, T2 relaxation times from Magnetic Resonance Fingerprinting radially undersampled data using analytical transformations

2021 ◽  
Vol 80 ◽  
pp. 81-89
Author(s):  
Nikolaos Dikaios ◽  
Nicholas E. Protonotarios ◽  
Athanasios S. Fokas ◽  
George A. Kastis
Keyword(s):  
Magnetic Resonance ◽  
Relaxation Times ◽  
T2 Relaxation ◽  
Undersampled Data

Determining the effect of water temperature on the T1 and T2 relaxation times of the lung tissue at 9.4 T MRI: A drowning mouse model

2021 ◽  
pp. 101836
Author(s):  
Kodama Saki ◽  
Hata Junichi ◽  
Kanawaku Yoshimasa ◽  
Nakagawa Hiroshi ◽  
Oshiro Hinako ◽  
...  
Keyword(s):  
Mouse Model ◽  
Water Temperature ◽  
Lung Tissue ◽  
Relaxation Times ◽  
T2 Relaxation ◽  
Effect Of Water ◽  
T1 And T2

Textural and pore size analysis of carbonates from integrated core and nuclear magnetic resonance logging: An Arbuckle study

2015 ◽  
Vol 3 (1) ◽  
pp. SA77-SA89 ◽  
Author(s):  
John Doveton ◽  
Lynn Watney
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Pore Size ◽  
Relaxation Times ◽  
T2 Relaxation Time ◽  
T2 Relaxation ◽  
Nmr Logging ◽  
The Core ◽  
Nuclear Magnetic

The T2 relaxation times recorded by nuclear magnetic resonance (NMR) logging are measures of the ratio of the internal surface area to volume of the formation pore system. Although standard porosity logs are restricted to estimating the volume, the NMR log partitions the pore space as a spectrum of pore sizes. These logs have great potential to elucidate carbonate sequences, which can have single, double, or triple porosity systems and whose pores have a wide variety of sizes and shapes. Continuous coring and NMR logging was made of the Cambro-Ordovician Arbuckle saline aquifer in a proposed CO2 injection well in southern Kansas. The large data set gave a rare opportunity to compare the core textural descriptions to NMR T2 relaxation time signatures over an extensive interval. Geochemical logs provided useful elemental information to assess the potential role of paramagnetic components that affect surface relaxivity. Principal component analysis of the T2 relaxation time subdivided the spectrum into five distinctive pore-size classes. When the T2 distribution was allocated between grainstones, packstones, and mudstones, the interparticle porosity component of the spectrum takes a bimodal form that marks a distinction between grain-supported and mud-supported texture. This discrimination was also reflected by the computed gamma-ray log, which recorded contributions from potassium and thorium and therefore assessed clay content reflected by fast relaxation times. A megaporosity class was equated with T2 relaxation times summed from 1024 to 2048 ms bins, and the volumetric curve compared favorably with variation over a range of vug sizes observed in the core. The complementary link between grain textures and pore textures was fruitful in the development of geomodels that integrates geologic core observations with petrophysical log measurements.

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