NMR permeability estimators in ‘chalk’ carbonate rocks obtained under different relaxation times and MICP size scalings

Rios, Edmilson Helton; Figueiredo, Irineu; Moss, Adam Keith; Pritchard, Tim; Glassborow, Brent; Domingues, Ana Beatriz; Azeredo, Rodrigo Bagueira de Vasconcellos

doi:10.1093/gji/ggw130

Cited by 21 publications

(14 citation statements)

References 33 publications

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“…Permeability can be determined from laboratory measurements, yet it is difficult to directly calculate the parameter at the subsurface (Rios et al, 2016). Many empirical methods have been proposed for the estimation of permeability based on the characteristic parameters of the T 2 distribution in downhole NMR applications, including the Schlumberger-Doll Research (SDR) method and the Timur-Coates method (Daigle & Dugan, 2009;Liu et al, 2017;Liu et al, 2019;Timur, 1968).…”

Section: Introductionmentioning

confidence: 99%

Nuclear Magnetic Resonance Characterization of Petrophysical Properties in Tight Sandstone Reservoirs

2020

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Permeability and bound water saturation (Swb) are key parameters reflecting the petrophysical properties of porous rocks. Nuclear magnetic resonance (NMR) has proved to be effective in investigating the properties of porous media. However, estimating Swb and the permeability in tight sandstone reservoirs based on conventional NMR methods, which requires the inversion of NMR echo data to obtain the transverse relaxation time (T2) distribution, proves to be a challenging task. In this study, a method is proposed to estimate Swb and the permeability in tight sandstone reservoirs based on the direct analysis of NMR echo data, thus avoiding the inversion process. A total of 20 tight sandstone samples from the Ordos Basin in China was taken for laboratory NMR measurements. The kernel function of the echo data was used to characterize the ratio distribution of bound water volume to pore volume for different pore sizes. Following this, an echo data calibration method was applied to estimate Swb without the inversion of the T2 distribution, and the window method was used to reduce the impact of noise in the echo data. Furthermore, models for estimating permeability were proposed based on the determined windows of the NMR echo data in the Swb estimation. The reliability of the proposed method for estimating Swb and permeability was verified by comparing the estimated and experimental results. Our study provides an efficient method for the estimation of petrophysical parameters in porous rocks based on the direct analysis of NMR echo data.

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Section: Introductionmentioning

confidence: 99%

Nuclear Magnetic Resonance Characterization of Petrophysical Properties in Tight Sandstone Reservoirs

2020

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“…Conversion of T 2 relaxation times, usually in seconds, to pore size radii (R p ), usually in micrometers, was performed using Eqs. (3) and (4) as described by Rios et al (2015):…”

Section: Methodsmentioning

confidence: 99%

“…where ρ 2 is the transverse surface relaxivity, S V is the pore surface-to-volume ratio, and F g is a geometric factor that represents planar (F g = 1), cylindrical (F g = 2) or spherical (F g = 3) pore shapes (Rios et al, 2015). In this work, pores were assumed to have a spherical shape, while ρ 2 was considered to be 35.7 µm/s, which is an average from the values calculated by Luna et al (2016), who used five samples from the same layer (Bed 2B) at Morro do Chaves Formation (Fig 1B ).…”

Section: Methodsmentioning

confidence: 99%

“…The T 2 is the transverse relaxation time constant due to the spin-spin relaxation interactions. The signal amplitudes for a pre-determined relaxation time range are obtained by a regularized numerical inversion due to the ill-posed nature of the problem (Coates et al, 1999;Rios et al, 2015). The amplitudes of the resultant T 2 distribution can be calibrated to fluid volume and, consequently, to porosity.…”

Section: Introductionmentioning

confidence: 99%

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Nuclear Magnetic Resonance to Characterize the Pore System of Coquinas From Morro Do Chaves Formation, Sergipe-Alagoas Basin, Brazil

et al. 2018

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ABSTRACT. Nuclear magnetic resonance (NMR) is a recognized petrophysical tool in the oil and gas industry to characterize reservoir rocks and fluids. In this study, the pore system of coquinas from a single bed of a quarry in the Morro do Chaves Formation was evaluated. These sedimentary rocks have been considered as a potential analogous to some Brazilian pre-salt reservoir rocks. The objective of this work was to characterize the porous system of coquinas in terms of total porosity and pore size distribution using low-field NMR. Conversion of T2 relaxation times to pore size radii was performed and literature cut-offs were applied for porosity partitioning. Coquinas were classified and ranked according to their percentage of macro, meso and micro porosity. This work verified quantitatively the pore system heterogeneities for the coquina samples and the variation in the layer from which they were extracted. The study provides some clues on lateral porosity and pore size variation in any reservoir for which this unit is an analogue.Keywords: Petrophysics, NMR, Total Porosity, Pore Size Distribution, Porosity Partitioning.RESUMO. Ressonância magnética nuclear (RMN) é uma técnica petrofísica reconhecida na indústria de óleo e gás pela sua capacidade de caracterizar rochas reservatório e seus fluidos saturantes. Neste estudo, foi avaliado o sistema poroso de coquinas pertencentes à uma camada de uma pedreira na Formação Morro do Chaves. Essas rochas sedimentares foram consideradas possíveis análogos de algumas rochas carbonáticas do pré-sal brasileiro. O objetivo do trabalho foi caracterizar o sistema poroso dessas coquinas em termos de porosidade total e distribuição de tamanho de poros utilizando RMN de baixo campo. Realizou-se a conversão dos tempos de relaxação T2 para raios de poro e empregou-se cut-offs da literatura para o particionamento da porosidade. As coquinas foram classificadas e ranqueadas de acordo com a sua porcentagem de macro, meso e micro poros. Verificou-se quantitativamente a heterogeneidade do sistema poroso das coquinas estudadas e a variação da camada sedimentar em que os plugues foram retirados. O estudo fornece informações sobre a variação lateral de porosidade e tamanho de poros para reservatórios que tenham a unidade estudada como análogo.Palavras-chave: Petrofísica, RMN, Porosidade Total, Distribuição do Tamanho de Poros, Particionamento da Porosidade.

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“…The specic principles, techniques, and permeability applications of T2-based NMR have been described in detail elsewhere. 25,26…”

Section: Nuclear Magnetic Resonance T2 Curvementioning

confidence: 99%

Microbially induced calcium carbonate precipitation driven by ureolysis to enhance oil recovery

Miao

Wang

et al. 2017

RSC Adv.

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NMR permeability estimators in ‘chalk’ carbonate rocks obtained under different relaxation times and MICP size scalings

Cited by 21 publications

References 33 publications

Nuclear Magnetic Resonance Characterization of Petrophysical Properties in Tight Sandstone Reservoirs

Nuclear Magnetic Resonance Characterization of Petrophysical Properties in Tight Sandstone Reservoirs

Nuclear Magnetic Resonance to Characterize the Pore System of Coquinas From Morro Do Chaves Formation, Sergipe-Alagoas Basin, Brazil

Microbially induced calcium carbonate precipitation driven by ureolysis to enhance oil recovery

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