Asymmetry Characteristics of Oil Production by Spontaneous Imbibition from Cores with Two Ends Open

Meng, Qingbang; Liu, Huiqing; Wang, Jing; Pang, Zhanxi

doi:10.1007/s11242-016-0722-y

Cited by 8 publications

(4 citation statements)

References 34 publications

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“…This is because the characteristic length is calculated based on the assumption of cores’ isotropy. In actual experiments, due to the different pore diameters of the cores’ imbibition surface and different capillary pressures, the imbibition speed of each end surface is asymmetric . Lyu et al .…”

Section: Resultsmentioning

confidence: 99%

“…In actual experiments, due to the different pore diameters of the cores' imbibition surface and different capillary pressures, the imbibition speed of each end surface is asymmetric. 51 Lyu et al 52 carried out similar experiments using tight sandstone. They found that under the TEO boundary conditions, the conclusion is similar.…”

Section: Influence Of Cementitious Mineralsmentioning

confidence: 99%

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Effects of Fracture Characteristics on Spontaneous Imbibition in a Tight Reservoir

et al. 2021

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Horizontal well fracturing technology is widely used in the development of shale gas resources. After the fracturing operations, natural and artificial fractures exist in the reservoir at the same time, which has significant effects on spontaneous imbibition to increase shale gas production. Based on nuclear magnetic resonance technology, this work studies the spontaneous imbibition property of fractured shale, including artificial and natural fractures, surface cemented minerals, boundary conditions, etc. The results show that the relaxation time spectra reflect the characteristics of water and gas migration in the rock pore space. The micropores and the small pores are the main storage space for water in shale. After water imbibition starts, the imbibition volume is roughly proportional to the square root of time. Through the comparative experiments on artificial fractures, natural fractures, and seamless cores, it is found that the existence of fractures can significantly promote water imbibition, and the imbibition speed of artificial fractured cores is faster than those of others. Because of the existence of artificial and natural fractures, the number of pores for gas discharge increases, and the imbibed volume is slightly more. When the cemented minerals such as quartzite and calcite are attached to the core surface, they have poor water sensitivity and block some of the pores, thus resulting in a slower imbibition speed. Different boundary conditions will not only affect the contact area between the core and water but also influence the types of imbibition, which changes the water flow path and imbibition speed. This study provides an important insight into spontaneous imbibition in gas shale after the fracturing operations.

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Section: Resultsmentioning

confidence: 99%

Section: Influence Of Cementitious Mineralsmentioning

confidence: 99%

Effects of Fracture Characteristics on Spontaneous Imbibition in a Tight Reservoir

et al. 2021

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“…However, asymmetry in oil production under TEO is observed, and this ambiguous behavior cannot be explained through the assumption that oil will be evenly displaced by SI from the two ends with a no-flow boundary at the middle of the core. Meng et al indicated that the difference in capillary back pressure of the two ends of the core can cause asymmetrical oil production. The capillary back pressure is related to the pore size at the open faces of the sample, which may differ in the same core .…”

Section: Resultsmentioning

confidence: 99%

Experimental Investigation of Countercurrent Spontaneous Imbibition in Tight Sandstone Using Nuclear Magnetic Resonance

et al. 2018

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Tight oil reservoirs are an unconventional hydrocarbon resource with great potential to help meet energy demands. Horizontal drilling and hydraulic fracturing has been extensively used for the exploitation of these unconventional resources, and fracturing fluids absorbed into formations by spontaneous imbibition (SI) is an important mechanism of oil production. In this paper, imbibition experiments combined with nuclear magnetic resonance were conducted to study the characteristics of fluid displacement in an oil/water system for tight sandstone. In addition, the relative contribution to oil recovery of different types of pores, effects of boundary conditions, and different surfactants on imbibition recovery was determined via the T 2 spectra of each sample. The results show that the tight sandstone features a multiscale pore structure, which is dominated by micropores and small mesopores. As the imbibition process begins, white oil is preferentially displaced from these relatively small pores by water and a large amount of oil production comes from the micropores. Boundary conditions are shown to have a significant impact on imbibition rate and ultimate recovery. Both are higher as the areas available for water imbibition increase. Deionized water with low concentrations of surfactants altered the wettability of the samples, from weakly water-wet to a strongly water-wet on the rock surfaces, while lowering interfacial tension (IFT) at the oil−water interface. Therefore, a higher oil recovery could be obtained to some extent, but enough IFT is still needed to ensure a large capillary force. Because conventional scaling equations do not account for the effect of wettability alteration, such as the addition of surfactants to a system, they cannot be employed to scale imbibition data well. This research demonstrates the imbibition characteristics of tight sandstone and several relevant affecting factors, providing crucial theory foundations for the development of tight oil formations.

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“…During the soaking process, fracturing fluid is imbibed into the reservoir and displaces the oil therein, thereby enhancing oil recovery. In fractured reservoirs, due to the randomness of the fracture morphology, the contact modes and contact areas between the fracturing fluid and rock are different, thus forming different boundary conditions. ,, Generally, the boundary conditions of cores are divided into all-faces-open (AFO), one-end-closed (OEC), two-ends-closed (TEC), two-ends-open (TEO), and one-end-open (OEO). − ,− Among them, the researches on OEC boundary condition has not received much attention. In addition to boundary conditions, the parameters that affect the imbibition characteristics also include core size, porosity, permeability, fluid surface tension, viscosity, and so on.…”

Section: Introductionmentioning

confidence: 99%

Study on Imbibition Characteristics of Glutenite with Different Boundary Conditions Based on NMR Experiments

et al. 2022

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A glutenite reservoir is an important unconventional oil resource. However, there are few experimental studies on the imbibition of glutenite, and the imbibition laws with different boundary conditions are not clear. In addition, the one-end-closed (OEC) boundary condition has not received much attention. In this paper, an analytical balance and a nuclear magnetic resonance (NMR) analyzer are used as experimental instruments to monitor the spontaneous imbibition process of saturated oil glutenite in deuterium water, and the imbibition characteristics of glutenite with five different boundary conditions are studied. The T 2 spectra show that oil is mainly distributed in micropores and mesopores, and the signal amplitudes in the micropores decrease significantly. The micropores correspond to greater capillary force, and they are the main space for imbibition. The imbibed volume measured by the mass method is basically consistent with the area changes of T 2 spectra, and the imbibition curves conform to the Handy model. The imbibition rates with different boundary conditions are different, but their gap is acceptable. Among them, one-end-open (OEO) and two-ends-open (TEO) boundary conditions are slightly higher. Imbibition recovery is related to the exposed areas of the cores, and all-faces-open (AFO) is the boundary condition most conducive to recovery. The normalized recovery model can better scale the three boundary conditions of AFO, OEC, and two-ends-closed (TEC), but there is a certain error in the scaling of TEO and OEO of core end seepage. This research contributes to understanding the effects of boundary conditions on spontaneous imbibition, which is of significance for analyzing the soak mechanism of glutenite reservoirs.

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Asymmetry Characteristics of Oil Production by Spontaneous Imbibition from Cores with Two Ends Open

Cited by 8 publications

References 34 publications

Effects of Fracture Characteristics on Spontaneous Imbibition in a Tight Reservoir

Effects of Fracture Characteristics on Spontaneous Imbibition in a Tight Reservoir

Experimental Investigation of Countercurrent Spontaneous Imbibition in Tight Sandstone Using Nuclear Magnetic Resonance

Study on Imbibition Characteristics of Glutenite with Different Boundary Conditions Based on NMR Experiments

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