Nuclear-Magnetic-Resonance Study on Mechanisms of Oil Mobilization in Tight Sandstone Reservoir Exposed to Carbon Dioxide

SPE Journal ◽  
2017 ◽  
Vol 23 (03) ◽  
pp. 750-761 ◽  
Author(s):  
Haitao Wang ◽  
Zengmin Lun ◽  
Chengyuan Lv ◽  
Dongjiang Lang ◽  
Weiyi Pan ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Co2 Injection ◽  
Tight Sandstone ◽  
Initial Exposure ◽  
Exposure Experiment ◽  
Sandstone Reservoir ◽  
Nuclear Magnetic

Summary Nuclear magnetic resonance (NMR) was used to investigate the exposure between carbon dioxide (CO2) and the sandstone matrix with a permeability of 0.218 md and a porosity of 9.5% at 40°C and 12 MPa (immiscible condition). Minimum miscibility pressure (MMP) between oil and CO2 was 17.8 MPa, determined by slimtube test at 40°C. The exposure process between CO2 and the sandstone matrix included first, second, third, and fourth exposure experiments. Before each exposure experiment started, there was a CO2-injection stage with a CO2 injection under a constant pressure of 12 MPa and at a constant rate to keep fresh CO2 (concentration of CO2 is 100% in gas phase) in the system. Each exposure experiment ended when the obtained T2 spectrum was unchanged (total amount of oil in tight matrix remains constant). These processes were similar to CO2 huff ’n’ puff. The results showed that (1) oil in all pores could mobilize as exposure time increases in the first exposure experiment. (2) The total original-oil-in-place (OOIP) recovery is 46.6% for oil in big pores (29 ms < T2 ≤ 645 ms)—this result is higher than the recovery (12.8%) for oil in small pores (T2 ≤ 29 ms). (3) Oil is mobilized fast in the initial exposure hours, and then the rate drops gradually until no more oil is produced. (4) Initially, the oil exists in pores with maximum relaxation times of 645 ms in the originally saturated core. After the CO2 injection, oil flows to pores with relaxation times slower than 645 ms, suggesting that oil in tight matrix is mobilized to the surface of core by swelling caused by CO2 diffusion. (5) The final OOIP recoveries of first, second, third, and fourth exposure experiments are 23.7, 7.2, 2.6, and 1.5%, respectively, and they decline exponentially. Oil mobilization in a tight-sandstone reservoir exposed to CO2 was observed by NMR T2 spectra under multiple exposure experiments. Mechanisms of oil mobilization were investigated (i.e., oil swelling, concentration-driven diffusion of hydrocarbons, and extraction of light components). The CO2 enhanced oil recovery (EOR) with multiple injections under immiscible conditions is acceptable and satisfactory in a tight-sandstone reservoir. CO2 huff ’n’ puff with optimized injection, soaking, and production process is an economic development method in a tight sandstone reservoir.

scholarly journals A method to determine nuclear magnetic resonance T 2 cutoff value of tight sandstone reservoir based on multifractal analysis

2020 ◽  
Vol 8 (4) ◽  
pp. 1135-1148 ◽  
Author(s):  
Yunbing Hu ◽  
Yinghai Guo ◽  
Junjian Zhang ◽  
Jingwen Shangguan ◽  
Mi Li ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Multifractal Analysis ◽  
Tight Sandstone ◽  
Cutoff Value ◽  
Sandstone Reservoir ◽  
Nuclear Magnetic

An emerging technology: Nuclear magnetic resonance microscopy

1988 ◽  
Vol 46 ◽  
pp. 1000-1001
Author(s):  
M.J. Hennessy ◽  
E. Kwok
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Relaxation Times ◽  
Basic Research ◽  
Local Environment ◽  
Magnetic Resonance Images ◽  
Nmr Microscopy ◽  
Mri Scans ◽  
Temperature Relaxation ◽  
Nuclear Magnetic

Much progress in nuclear magnetic resonance microscope has been made in the last few years as a result of improved instrumentation and techniques being made available through basic research in magnetic resonance imaging (MRI) technologies for medicine. Nuclear magnetic resonance (NMR) was first observed in the hydrogen nucleus in water by Bloch, Purcell and Pound over 40 years ago. Today, in medicine, virtually all commercial MRI scans are made of water bound in tissue. This is also true for NMR microscopy, which has focussed mainly on biological applications. The reason water is the favored molecule for NMR is because water is,the most abundant molecule in biology. It is also the most NMR sensitive having the largest nuclear magnetic moment and having reasonable room temperature relaxation times (from 10 ms to 3 sec). The contrast seen in magnetic resonance images is due mostly to distribution of water relaxation times in sample which are extremely sensitive to the local environment.

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.

Saturated carbon dioxide nanofluids enhanced oil recovery in carbonate reservoir cores using nuclear magnetic resonance

2021 ◽  
Author(s):  
Yongsheng Tan ◽  
Qi Li ◽  
Liang Xu ◽  
Xiaoyan Zhang ◽  
Tao Yu
Keyword(s):  
Carbon Dioxide ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Residual Oil ◽  
Core Flooding ◽  
Nuclear Magnetic

<p>The wettability, fingering effect and strong heterogeneity of carbonate reservoirs lead to low oil recovery. However, carbon dioxide (CO<sub>2</sub>) displacement is an effective method to improve oil recovery for carbonate reservoirs. Saturated CO<sub>2</sub> nanofluids combines the advantages of CO<sub>2</sub> and nanofluids, which can change the reservoir wettability and improve the sweep area to achieve the purpose of enhanced oil recovery (EOR), so it is a promising technique in petroleum industry. In this study, comparative experiments of CO<sub>2</sub> flooding and saturated CO<sub>2</sub> nanofluids flooding were carried out in carbonate reservoir cores. The nuclear magnetic resonance (NMR) instrument was used to clarify oil distribution during core flooding processes. For the CO<sub>2</sub> displacement experiment, the results show that viscous fingering and channeling are obvious during CO<sub>2</sub> flooding, the oil is mainly produced from the big pores, and the residual oil is trapped in the small pores. For the saturated CO<sub>2</sub> nanofluids displacement experiment, the results show that saturated CO<sub>2</sub> nanofluids inhibit CO<sub>2</sub> channeling and fingering, the oil is produced from the big pores and small pores, the residual oil is still trapped in the small pores, but the NMR signal intensity of the residual oil is significantly reduced. The final oil recovery of saturated CO<sub>2</sub> nanofluids displacement is higher than that of CO<sub>2</sub> displacement. This study provides a significant reference for EOR in carbonate reservoirs. Meanwhile, it promotes the application of nanofluids in energy exploitation and CO<sub>2</sub> utilization.</p>

scholarly journals Preliminary magnetic resonance relaxometric analysis of Fricke gel dosimeters produced with polyvinyl alcohol and glutaraldehyde

2017 ◽  
Vol 32 (3) ◽  
pp. 242-249 ◽  
Author(s):  
Salvatore Gallo ◽  
Giorgio Collura ◽  
Giuseppina Iacoviello ◽  
Anna Longo ◽  
Luigi Tranchina ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Polyvinyl Alcohol ◽  
Dose Range ◽  
Relaxation Times ◽  
Ion Concentration ◽  
Nuclear Magnetic Resonance Relaxometry ◽  
New Formulation ◽  
Nuclear Magnetic

This work describes the preliminary analysis of Fricke gels dosimeters characterized by a new formulation making use of a matrix of polyvinyl alcohol cross-linked by adding glutaraldehyde and analyzed by means of nuclear magnetic resonance relaxometry. In previous optical studies, these gels have shown promising dosimetric features in terms of photon sensitivity and low diffusion of ferric ions produced after irradiation. In this work, we used a portable nuclear magnetic resonance relaxometer to measure the relaxation times (which are important for dosimetric applications) of these gel materials. For this purpose, we performed a study for optimizing the acquisition parameters with a nuclear magnetic resonance relaxometer. Gel samples were exposed to clinical 6 MV photons in the dose range between 0 and 20 Gy. Nuclear magnetic resonance relaxometry measurements were per- formed and the sensitivity to photon beams was measured for various values of the Fe2+ ion concentration. The analyses pointed out that the MR signal increases as the Fe2+ content in- creases and the increase is about 75 % when the concentration of Fe2+ ions is increased from 0.5 mM to 2.5 mM. Furthermore, the sensitivity improvement achieved with increasing the Fe2+ concentration is about 60 %. This paper shows that the portable nuclear magnetic resonance relaxometer used for analysis of porous materials can be used for characterization of these dosimetric gels and this study can be considered as the first step for the characterization of these dosimeters which in future could be used for 3-D dose mapping in clinical applications.

Nuclear magnetic resonance microscopy of single neurons under hypotonic perturbation

1996 ◽  
Vol 271 (6) ◽  
pp. C1895-C1900 ◽  
Author(s):  
E. W. Hsu ◽  
N. R. Aiken ◽  
S. J. Blackband
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Single Cells ◽  
Extracellular Volume ◽  
Relaxation Times ◽  
Volume Ratio ◽  
Cell Swelling ◽  
Single Neurons ◽  
Apparent Diffusion Coefficients ◽  
Nuclear Magnetic

Nuclear magnetic resonance (NMR) characteristics of water in perfused single neurons undergoing a 20% hypotonic perturbation were examined quantitatively using NMR microscopy. The transverse relaxation times (T2) in the cytoplasm and nucleus increased by 24.0 +/- 8.5% (average +/- SE, n = 8) and 29.7 +/- 5.3% (n = 6), respectively, whereas the apparent diffusion coefficients (ADC) showed no significant change. These findings are consistent with the behaviors of a perfect osmometer and with accepted molecular relaxation and diffusion models and have significant impacts on current views of properties of cellular water. Furthermore, the results suggest that the increase of tissue intracellular-to-extracellular volume ratio during cell swelling is the predominant mechanism underlying the ADC reduction in acute brain ischemia. These data are the first direct quantitative measurements of the NMR characteristics of water in the cytoplasm and nucleus of single cells undergoing physiological perturbations and may lead to an improved diagnostic capability for NMR imaging in a variety of disease states.

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