Nuclear magnetic resonance characterization of porosity-preserving microcrystalline quartz coatings in Fontainebleau sandstones

Jácomo, Marta Henriques; Trindade, R. I.; French, Marsha W.; Lucas-Oliveira, Éverton; Montrazi, Elton Tadeu; Bonagamba, Tito J.

doi:10.1306/01301918104

Cited by 8 publications

(3 citation statements)

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“…The peak value and area of the curve represent the pore volume of the rock, and the curve peak's continuity reflects the pores' connectivity characteristics. The surface relaxivity was determined by combining the relaxation duration and the PSD which were acquired using different methods [19,[31][32][33]. Yao and Liu compared the specimen's T 2 spectrum of NMR with the PSD of MIP and demonstrated that specimen T 2 spectrum is superior in practicability and evaluation accuracy and can be used to study the distribution of pore throat structure [34].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Microstructure Characteristics and Deformation Mechanisms of the Carbonaceous Slate under Hydromechanical Coupling

Yang

Chen

2023

Geofluids

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Carbonaceous slate inevitably possesses microscopic pores, microcracks, cleavages, and bedding planes in complex geoenvironment during the diagenesis processes. The microstructure of carbonaceous slate changes apparently under the effects of underground water infiltration, tectonic stress, and engineering disturbance, which induces the large deformation of rock mass and influences the stability of geotechnical engineering projects. To investigate the microstructure characteristics and reveal deformation mechanisms of carbonaceous slate under the influence of water pressure and stress, the variations of the pore size distribution(PSD), connectivity of pores, and porosity of samples during water injection and triaxial compression were studied using multiple methods. The results indicated that voids include plate-like micropores and microcracks, which are discontinuous without external stress. The micropores with a size of less than 1 μm dominate in number. The flaky particles were extruded and bent at a confining pressure, which caused the intermediate pores to form and altered the PSD of the samples. Hence, the connectivity dramatically improved and resulted in increased permeability. Water with dissolved clay minerals and small particles could move between micropores and microcracks during the water injection process. The elastic deformation of the particles recovered, and the intermediate pores disappeared when the imbalanced forces on two sides of the particles were narrowed. Pore water pressure affected the effective stress state and decreased the cohesion and stiffness of the rock. In the lower stress state, the porosity had a certain range of decrease (about 0.2%) mainly due to micropore compression, while the microcrack sprouted and expanded with the increase of compressive stress, resulting in the extension of porosity. The interaction of the stress and water seepage on the slate reduced the rock strength and favored the deformation, leading to a large macrodeformation of the soft rock in the long run.

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Section: Introductionmentioning

confidence: 99%

Investigation of the Microstructure Characteristics and Deformation Mechanisms of the Carbonaceous Slate under Hydromechanical Coupling

Yang

Chen

2023

Geofluids

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“…Transverse relaxation times measured at 2 MHz or 20 MHz (*), using a log-normal fitting of curves and calculated surface relaxivity (ρ2); (1) is Group1; (2) is Group 2 Each peak corresponds to one family of pores. Note that Group 2 (FB155) and Group 1 (FB 217 and FB 10) have similar pore sizes, but the former shows much shorter T2 times, therefore revealing a slight displacement towards shorter times (adapted fromJácomo et al, 2019).…”

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confidence: 99%

Explaining Nuclear Magnetic Resonance T2 shifts in sandstones with anomalous porosity

Jácomo¹,

Trindade²,

Lucas-Oliveira³

et al. 2019

Proceedings of the 16th International Congress of the Brazilian Geophysical Society&Expogef

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“…onde a razão # / deve ser estimada experimentalmente. 34 [35][36][37] Para um meio poroso, espera-se que o decaimento da magnetização não seja representado pelas Equações 8 e 9, uma vez que a magnetização é dada por:…”

Section: Rmn Em Meios Porososunclassified

Modelagem físico-computacional da RMN em meios porosos - aplicações na indústria do petróleo

Lucas-Oliveira¹

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Extracting and understanding morphological properties of porous media is the focus of many areas of knowledge. In the case of oil industry, extracting the tridimensional morphological features of rock reservoirs allows the evaluation of the well productivity. Nuclear Magnetic Resonance (NMR) is one of the most important techniques applied in the study of reservoir rocks, capable of providing information about both their morphologies and the confined fluids. The most used parameters measured by NMR to study fluids in reservoir rocks are the magnetic relaxation and diffusion coefficients. Fluid molecules diffuse through the pore space and relax due to the fluid-surface interaction, macroscopically defined by the magnetic surface relaxivity ρ. The magnetic surface relaxation time TS is given in terms of three parameters: ρ, pore size distribution (PSD), and pore connectivity, being ρ extremely important and difficult to measure. The magnetic surface relaxivity can be determined by correlating TS to the PSD obtained from other techniques. However, in general, pore length scale defined by the molecular diffusion during the NMR magnetic relaxation is not equivalent to pore sizes measured, for example, by thin section and mercury intrusion. While the thin section offers essentially two-dimensional information about the pores, the mercury intrusion technique measures the bulk pore-throat size distribution. Due to this reason, a new NMR computational physics approach was proposed to correlate magnetic relaxation experimental data with those simulated using Digital Porous Media obtained by X-ray microcomputed tomography, which offers an alternative method to measure of ρ. This computational physics method, unlike the others, preserves the porous media morphology, molecular dynamics and NMR properties. Additionally, it is straightforward to implement advanced NMR pulse sequences using the proposed computational model, including those carried out under magnetic field gradients. Thus, it is possible to reproduce data resulting from NMR techniques applied in either laboratory or well-logging conditions. Therefore, the proposed computational physics model is capable of reproducing the NMR parameters of interest to the oil industry, most notably the longitudinal and transverse relaxation times T1 and T2, as well as the diffusion coefficient D and their correlations T1xT2, DxT2, and T2xT2.

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Nuclear magnetic resonance characterization of porosity-preserving microcrystalline quartz coatings in Fontainebleau sandstones

Cited by 8 publications

References 50 publications

Investigation of the Microstructure Characteristics and Deformation Mechanisms of the Carbonaceous Slate under Hydromechanical Coupling

Investigation of the Microstructure Characteristics and Deformation Mechanisms of the Carbonaceous Slate under Hydromechanical Coupling

Explaining Nuclear Magnetic Resonance T2 shifts in sandstones with anomalous porosity

Modelagem físico-computacional da RMN em meios porosos - aplicações na indústria do petróleo

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