An experimental investigation of spontaneous imbibition in gas shales

Roychaudhuri, B.; Tsotsis, Theodore T.; Jessen, Kristian

doi:10.1016/j.petrol.2013.10.002

Cited by 207 publications

(110 citation statements)

References 35 publications

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“…Therefore, the mathematical model for imbibition/diffusion should be simplified to solve the equation easily. The initial stage of imbibition mainly involves the imbibition of micro-fractures or macro-pores, and then it slowly becomes mesopore or micropore imbibition at a later stage (Yang et al, 2016;Meng et al, 2015;Roychaudhuri et al, 2013). There is an obvious proportional relationship between the imbibition volume and square root of time in the initial stage, indicating that the microfractures and macro-pores imbibition model can be established based on the assumption of parallel straight capillary bundles.…”

Section: Quantitative Interpretation Of the Imbibition/diffusion Relamentioning

confidence: 99%

“…The pore structure in shale is more complicated than that in conventional sandstone, which causes the special imbibition characteristics in gas shale. As for the dual-porosity nature of shale, shale exhibits a distinct transition from a higher imbibition rate to a lower imbibition rate (Roychaudhuri et al, 2013). The low imbibition rate suggests that the matrix reflects a relatively low pore connectivity depicted by the slope in the curve [log (cumulative imbibition) vs. log (imbibition time)].…”

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical study on the relationship between water imbibition and salt ion diffusion in fractured shale reservoirs

Liu

Shi

et al. 2017

Journal of Natural Gas Science and Engineering

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a b s t r a c tField observations demonstrate that shale gas wells feature a low flowback efficiency (<30%) and highsalinity flowback water (approximately 200kppm) after multistage hydraulic fracturing operations. The water recovery and salinity profile could be regarded as a critical method for volumetric and chemical analyses to characterize the reservoir properties and complexity of the fractured network. This paper aims to understand the relationship between fracturing imbibition and ion diffusion, which are responsible for inefficient water recovery and high-salinity flowback fluid, respectively. Comparative imbibition experiments are performed on different shale and sandstone samples, and an electrical conductivity meter is used to monitor the change in ion concentration change of the imbibition fluid. A mathematical model based on theoretical analysis is proposed to clarify the correlation between imbibition and ion diffusion. Both the experimental and analytical solution results show that the imbibition fluid conductivity resulting from ion diffusion is proportional to the square root of time, which is similar to the law of capillary-driven imbibition into porous media. Water imbibition into gas shale and ion diffusion into water proceed simultaneously in the opposite direction, and only the imbibition front contacting the pore wall with salt ions can cause the salt ions to dissolve and diffuse into water. The analytical solution results also indicate that the effects of the porosity, surface tension, contacting area and wetting angle on the water imbibition rate are in consistent with that of the ion diffusion rate. The permeability, however, shows a positive correlation with the imbibition rate and a negative correlation with the ion diffusion rate. The initial water saturation is negatively related to the imbibition rate, and positively related to the ion diffusion rate. In addition, smectite and I/S could enhance the imbibition and diffusion rates. It is observed that illite concentration has no relationship with the imbibition and diffusion rates, indicating that illite minerals do not significantly affect the imbibition/diffusion rate in these clay-rich shales. This research contributes to understanding the correlation between imbibition and ion diffusion, which is significant for flow-back analysis after fracturing operations.

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Section: Quantitative Interpretation Of the Imbibition/diffusion Relamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental and numerical study on the relationship between water imbibition and salt ion diffusion in fractured shale reservoirs

Liu

Shi

et al. 2017

Journal of Natural Gas Science and Engineering

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“…Water imbibition has always been recognized as a source that leads to productivity damage in the conventional theory. Spontaneous imbibition will cause formation damage based on the conventional theory of water blockage, especially in unconventional reservoirs with containing extremely small pores with strong capillary pressure (less than 100 nm) (Bennion and Thomas, 2005;Roychaudhuri et al, 2013;Odumabo et al, 2014). However, recent studies show that spontaneous imbibition of fracturing fluid can be a driving force to enhance gas recovery in shale gas reservoirs (Dehghanpour et al, 2012;Roychaudhuri et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Water imbibition of shale and its potential influence on shale gas recovery—a comparative study of marine and continental shale formations

Shen

et al. 2016

Journal of Natural Gas Science and Engineering

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a b s t r a c tA large volume of fracturing fluid is pumped into a well to stimulate shale formation. The water is imbibed into the reservoir during this procedure. The effect of the imbibed water on gas recovery is still in debate. In this work, we study the spontaneous imbibition of water into marine shale samples from the Sichuan Basin and continental shale samples from Erdos Basin to explore the fluid imbibition characteristics and permeability change during water imbibition.Comparison of imbibition experiments shows that shale has stronger water imbibition and diffusion capacity than relatively higher permeability sandstone. Once the imbibition stops, water in shale has stronger ability to diffuse into deeper matrix, the water content in the main flow path decreases.Experiments in this study show that marine shale has stronger water imbibition capacity than continental shale. The permeability of continental shale decreases significantly with increasing imbibition water volume; however, the permeability of marine shale decreases at first and increases after a certain imbibition time. The induced fracture is obvious in the marine shale. SEM analysis shows that the relationship between the clay mineral and organic matter of continental shale is much more complex than that of marine shale, which may be the key factor restricting the water imbibition because the flow path is trapped by swelled clay minerals.Through this study, we concluded that whether gas recovery benefits from water imbibition depends on three aspects: 1) the diffusion ability of liquid into matrix; 2) the new cracks introduced by imbibed water; and 3) the formation sensibility. This study is useful for optimizing fracture fluids and determining the best flow-back method.

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“…The experiments concerning spontaneous imbibition have been performed with many types of rocks, especially sandstones and shales [43][44][45][46][47]. These studies have paid much attention to the damage caused by fracturing fluid filtration under the effect of spontaneous imbibition.…”

Section: Monitor Spontaneous Imbibition Using Pulse-decay Permeabilitmentioning

confidence: 99%

Impact of Petrophysical Properties on Hydraulic Fracturing and Development in Tight Volcanic Gas Reservoirs

Shen¹,

Meng²,

Liu³

et al. 2017

Geofluids

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The volcanic reservoir is an important kind of unconventional reservoir. The aqueous phase trapping (APT) appears because of fracturing fluids filtration. However, APT can be autoremoved for some wells after certain shut-in time. But there is significant distinction for different reservoirs. Experiments were performed to study the petrophysical properties of a volcanic reservoir and the spontaneous imbibition is monitored by nuclear magnetic resonance (NMR) and pulse-decay permeability. Results showed that natural cracks appear in the samples as well as high irreducible water saturation. There is a quick decrease of rock permeability once the rock contacts water. The pores filled during spontaneous imbibition are mainly the nanopores from NMR spectra. Full understanding of the mineralogical effect and sample heterogeneity benefits the selection of segments to fracturing. The fast flowback scheme is applicable in this reservoir to minimize the damage. Because lots of water imbibed into the nanopores, the main flow channels become larger, which are beneficial to the permeability recovery after flow-back of hydraulic fracturing. This is helpful in understanding the APT autoremoval after certain shut-in time. Also, Keeping the appropriate production differential pressure is very important in achieving the long term efficient development of volcanic gas reservoirs.

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An experimental investigation of spontaneous imbibition in gas shales

Cited by 207 publications

References 35 publications

Experimental and numerical study on the relationship between water imbibition and salt ion diffusion in fractured shale reservoirs

Experimental and numerical study on the relationship between water imbibition and salt ion diffusion in fractured shale reservoirs

Water imbibition of shale and its potential influence on shale gas recovery—a comparative study of marine and continental shale formations

Impact of Petrophysical Properties on Hydraulic Fracturing and Development in Tight Volcanic Gas Reservoirs

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