Evaluation of Gas Saturation During Water Imbibition Experiments

Ding, Meng; Kantzas, Apostolos; Lastockin, D.

doi:10.2118/2003-021

Cited by 4 publications

(3 citation statements)

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“…Previous studies have established a mathematical model that takes into account several factors, including the surface relaxation rate of low-order coal, the surface tension of water on coal, and pore curvature, while also identifying gravity as a non-negligible factor in vertical well flow. 47 The capillary force plays a crucial role during the rapid rising stage, where smaller pore sizes exhibit stronger capillary forces, facilitating the capillary absorption of water. During the rapid wicking stage, water rapidly percolates into ultramicropores and then transfers rapidly into micropores and small pores.…”

Section: Mechanism Of Spontaneous Imbibition Andmentioning

confidence: 99%

Experimental Study on Spontaneous Imbibition of Coal Samples of Different Ranks Based on the NMR Relaxation Spectrum

Wang,

Du,

et al. 2023

ACS Omega

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The comprehension of the mechanisms governing spontaneous water imbibition in gas–water systems plays a significant role in the operation of hydraulic fracturing and the development of coalbed methane (CBM). In this study, nuclear magnetic resonance (NMR) techniques were used to investigate the pore structure and fluid behavior of different rank coal samples during spontaneous imbibition. Analyses were conducted on the 1D NMR T 2 spectrum, 2D NMR T 1–T 2 spectrum, and layer division T 2 spectra to achieve accurate and detailed information about the internal pore structure of coal and the characteristics of fluid transport during spontaneous imbibition. Low-rank coal exhibits good pore connectivity and favorable pore sorting characteristics, indicating favorable reservoir conditions. High-rank coal has larger pore spaces and highly developed micropores, which are highly beneficial for gas adsorption. However, its poor pore sorting characteristics and connectivity limit the migration and diffusion of fluids within the reservoir. The imbibition capacity follows a specific order of contribution, with small pores (10–50 nm) having the most significant role, followed by micropores (2–10 nm), ultramicropores (r < 2 nm), mesopores (50–1000 nm), macropores (1000–10,000 nm), and microfractures (r ≥ 10,000 nm). Low-rank coal stands out due to the restricted development of ultramicropores and small pores, leading to a different contribution of imbibition capacity compared to other samples, where macropores and microfractures dominate over all pore types. The coal reservoirs with favorable pore sorting characteristics and pore connectivity tend to exhibit a tendency toward rapid saturation and attainment of a prompt stable state during the hydraulic fracturing process. Finally, the mechanism of the late retreat effect of imbibition and the laws governing different coal ranks, pore structures, and fluid transport were discussed. This study offers comprehensive analyses of the mechanism of coal spontaneous imbibition and the characteristic laws of fluid seepage, providing insights into the optimization of CBM recovery and reservoir management.

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Section: Mechanism Of Spontaneous Imbibition Andmentioning

confidence: 99%

Experimental Study on Spontaneous Imbibition of Coal Samples of Different Ranks Based on the NMR Relaxation Spectrum

Wang,

Du,

et al. 2023

ACS Omega

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“…3,10 Researchers have devoted many theoretical models and laboratory experiments to studying the spontaneous imbibition characteristics for water−gas−rock or water−oil−rock systems at the core scale, such as the effects of microstructure, 5,11,12 physical properties, 4 boundary conditions, 3,10 rock mineralogy, 5 initial water saturation, 13−15 temperature, 3 wettability, 3 and soaking time. 4 Among these investigations, nuclear magnetic resonance (NMR) was introduced as an effective and a nondestructive technique for conducting spontaneous imbibition experiments to characterize the fluid distributions in conventional sandstones, 10 gas shale cores, 16,17 unconsolidated sediments, 12,18 thinly layered source rocks, 19 and tight reservoir cores. 3,17,20 For tight reservoir cores, Meng et al 17 monitored the process of spontaneous imbibition in cocurrent and countercurrent displacing gas combined with NMR.…”

Section: Introductionmentioning

confidence: 99%

Differences in the Fluid Characteristics between Spontaneous Imbibition and Drainage in Tight Sandstone Cores from Nuclear Magnetic Resonance

et al. 2018

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As the water injected during hydraulic fracturing is imbibed and then displaced in the matrix of tight reservoirs, it is meaningful to characterize the fluid distributions and percolation dynamics during these two processes as they significantly affect production. In this study, 6 tight sandstone cores from the Chinese Ordos Basin were selected to experimentally study the fluid seepage and distributions during spontaneous imbibition and drainage using a low-field nuclear magnetic resonance (NMR) core analysis unit. Dry cores were first tested via cocurrent imbibition and then centrifuged from fully saturated to irreducible water saturation to simulate the imbibition and drainage processes, respectively. The weights and T 2 spectra were measured concurrently for each step. The results showed that the volume of imbibed water increased rapidly during the first 3000 min and reached a constant value at the end of the experiment; the final imbibition water saturation S w i m ranged from 48.52% to 89.20%. The irreducible water saturation S w i r was reached after a centrifuge speed of 10 000 r/min and varied from 40.46% to 53.28%. The gas and water relative permeabilities were estimated by combining the T 2 spectra for different water saturations, which indicated the effect of the capillary force and pore–throat structure on the different fluid seepage characteristics during spontaneous imbibition and drainage. The T 2 time was converted to the corresponding pore–throat radius by combining the fully water-saturated T 2 spectra and pore distributions from a constant-rate mercury injection. Micropores of 0–2 μm were identified as the dominant pore spaces for imbibed water during spontaneous imbibition and the water remained after centrifugation, whereas a small amount of water was imbibed or remained in pores larger than 20 μm. The physical properties, microstructure, and dispersed clay minerals were considered to be the three dominant factors of the fluid dynamics and distribution differences, and the effects were stronger during spontaneous imbibition.

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“…On the estimation of fluid saturation in spontaneous imbibition, using 2D NMR in organic shales, Nicot et al 28 gave experimental evidence of an NMR contrast between oil and water in organic shales and explored the cause of high T 1 / T 2 ratio. A methodology proposed from Ding et al 29 evaluated the mechanisms of water imbibition in sandstone gas reservoirs by using NMR to measure the amount of imbibed water and the gas saturation. Freedman et al 30 took advantage of two advances in NMR well logging, from which gained the brine and oil T 2 distributions to compute saturation and oil viscosity values.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Oil Saturation Development behind Spontaneous Imbibition Front Using Nuclear Magnetic Resonance T2

Liang

Jiang

et al. 2017

Energy Fuels

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Spontaneous imbibition is a critical mechanism for the development of water-wet fractured reservoirs. In order to improve the ultimate oil recovery, it is important to understand the change of in situ oil saturation during the spontaneous imbibition process. In this study, spontaneous imbibition experiments of two ends open (TEO) are conducted using unconsolidated sand packs. The sand packs are filled with quartz sands of three different particle sizes respectively and are fully oil-saturated. Nuclear magnetic resonance (NMR) T2 is used to monitor the saturation development behind spontaneous imbibition front. For porous media of the same lithology, the imbibition speed and final oil recovery decline with the reduction of average pore size. As the imbibition front constantly moves forward, the change of oil saturation behind the imbibition front does exist, and the major decrease of oil saturation happens in the large pore space. In terms of a particular region behind the spontaneous imbibition front, with the progression of the front, the oil saturation gradient in the area declines. Specifically, the dramatic gradient descent occurs when the spontaneous imbibition front just passes by. The smaller the average pore size is (the larger the mesh of sand is), the more rapid the saturation changes behind imbibition front. For porous media of small pore size, even when the imbibition front has moved far away, oil saturation still changes a lot.

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Evaluation of Gas Saturation During Water Imbibition Experiments

Cited by 4 publications

References 0 publications

Experimental Study on Spontaneous Imbibition of Coal Samples of Different Ranks Based on the NMR Relaxation Spectrum

Experimental Study on Spontaneous Imbibition of Coal Samples of Different Ranks Based on the NMR Relaxation Spectrum

Differences in the Fluid Characteristics between Spontaneous Imbibition and Drainage in Tight Sandstone Cores from Nuclear Magnetic Resonance

Investigation of Oil Saturation Development behind Spontaneous Imbibition Front Using Nuclear Magnetic Resonance T2

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