Impact of Flowback Dynamics on Fracture Conductivity

Осипцов, А. Н.; Гарагаш, И. А.; Боронин, С. А.; Tolmacheva, Kristina; Lezhnev, Konstantin; Paderin, Grigory

doi:10.1016/j.petrol.2019.106822

Cited by 32 publications

(11 citation statements)

References 28 publications

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“…The success of hydraulic fracturing relies on a multitude of parameters such as proppant transport and placement efficiency, ,− proppant strength relative to the downhole minimum horizontal stress, − hardness of the proppant and fractured formation shaping the proppant embedment tendency, − fracturing fluid leak-off into the formation and its flow-back, − and fracture propagation. − Although surface properties directly impact flow and transport, there are very few studies that examined the effect of proppant wettability characteristics on fracture flow performance. Those studies performed either microscale or macroscale core flooding or proxy experiments like sandpack flooding and column testing to infer the fluid flow efficiency for different proppant affinities.…”

Section: Introductionmentioning

confidence: 99%

Pore-Scale Study of Wettability Alteration and Fluid Flow in Propped Fractures of Ultra-Tight Carbonates

Elkhatib

Xie

Mohamed³

et al. 2023

Langmuir

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The in situ change in oil flow behavior inside propped fractures due to wettability alteration of proppant grains and fracture surfaces was thoroughly investigated for the first time in this study. A series of microscale flow experiments were performed in mixed-wet fractured and propped miniature ultra-tight carbonate cores where the effect of wettability on oil bridging and fracture oil layer integrity was probed during oil production. During the initial production, proppant wettability changed toward an intermediate-wet state (contact angle (CA) = 96°) while that of fracture surfaces became strongly oil-wet (CA = 139°). Consequently, the fracture oil layer grew in size on both fracture surfaces and imbibed into the proppant pack through piston-like displacement and pore body filling until oil bridges were formed during oil injection. However, subsequent waterflooding induced thinning and rupturing of those bridges due to the accompanying reduction in the threshold capillary pressure of the proppant at higher aging times. The in situ chemical treatment of the proppant by a cationic surfactant (dodecyl tri-methyl ammonium bromide) could reverse its wettability toward weakly water-wet state (CA = 78°) after oil solubilization from the sand grains followed by substitutive surfactant adsorption. Surfactant injection also impacted the wettability of the fracture surface due to oil solubilization, reducing its mean contact angle down to an intermediate range (CA = 99°). As a result, the following oil production cycle yielded a smaller fracture oil layer. The surfactant effect on proppant wettability lasted for 2 weeks while its effect on fracture wettability lasted for more than 6 weeks. Similar flow cycles were performed with an anionic nanoparticle (graphene quantum dot) with hydrogen bonding ability. The nanoparticle solution yielded a quick reduction of the proppant and fracture surface contact angles to nearly 77° and 115°, respectively. Proppant wettability alteration occurred because the nanoparticles self-assembled at the three-point contact region between adsorbed oil and quartz surfaces, leading to oil solubilization in intermediate-wet regions while oil-wet regions remained unchanged. Therefore, re-introducing oil into the fracture instantaneously re-instated the initial wettability state of proppant grains (CA = 88°), deeming the nanoparticle solution ineffective. This study revealed that oil production through hydraulic fractures can be enhanced by monitoring the wettability of the proppant pack. If the production has a high water cut, it is beneficial to use chemical agents that reduce the proppant contact angles to a weakly water-wet state in order to preserve the hydraulic conductivity of the oil layer.

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Section: Introductionmentioning

confidence: 99%

Pore-Scale Study of Wettability Alteration and Fluid Flow in Propped Fractures of Ultra-Tight Carbonates

Elkhatib

Xie

Mohamed³

et al. 2023

Langmuir

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“…The study is just around the upper structure wind load response of dynamic mechanical characteristics, but seldom consider the lower inherent mechanical properties of rock mass structural materials and its stability affected by wind load counter attack tall structures. However, the research of high structure stability evaluation of the wind vibration and wind resistance design has its limitations (Ken et al, 2015;Osiptsov et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Coupling characteristics of creep fracture of rock foundation on wind turbine under wind induced vibration

Wang

Nie

Cao

2022

Preprint

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This paper presents the elastoplastic creep fracture characteristics and bearing stability of rock foundation for wind turbine based on the influence of wind load. Combined with the superstructure-concrete foundation-rock foundation lay load and boundary conditions, the wind load standard value and wind turbine system composition were obtained under normal wind condition, and then the forced vibration model of viscous damping two-degree-of-freedom system was established. Furthermore, the mode characteristics, frequency characteristic equations and the relations of the first and second order natural frequencies were obtained. According to the plastic yield characteristics of power hard rock base material, the analytical expressions of displacement, plastic zone and plastic state of I-II composite crack were obtained by coupling Mohr-Coulomb plastic yield condition and creep fracture characteristics. Simultaneously, the improved nonlinear creep model equation and accelerated creep fracture time were also obtained based on improved Kelvin nonlinear accelerated creep model. Combined with the example, it is verified that the accelerated creep displacement and crack propagation of rock foundation are obvious, considering the wind bracing and creep characteristics of rock foundation. Final, the failure modes of rock-foundation are compressive shear, local shear and bending-shear.It is necessary to timely reinforce the interface of foundation rock foundation.

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“…Multistage hydraulic fracturing (MHF) was utilized in the development of tight sand gas reservoirs earlier than that of shale gas reservoirs. − In the tight sand gas reservoir, the flowback process is critical, because the fracturing fluids create a blocking at the matrix-fracture interface after MHF operation, which hinders gas-flow capacity because of the low reservoir permeability (≤0.1 mD) and porosity (≤10%). − The clay swelling and migration caused by the fluid-rock reaction is another reason for impairing the permeability of the tight sand gas reservoir . Therefore, pursuing a high flowback rate of hydraulic fracturing fluid (HFF) is the key to gaining a high tight sand gas production rate.…”

Section: Introductionmentioning

confidence: 99%

Zero Flowback Rate of Hydraulic Fracturing Fluid in Shale Gas Reservoirs: Concept, Feasibility, and Significance

et al. 2021

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A high flowback rate of hydraulic fracturing fluid (HFF) yields a high gas production rate in a tight sand gas reservoir. This idea is well followed when it comes to the hydraulic fracturing of a shale gas well. Therefore, numerous studies have focused on increasing the flowback rate of HFF in shale gas reservoirs to mitigate the water blocking damage. Yet, only a small portion of the injected fluid (less than 20%) could be recovered during flowback operation. Moreover, there is no good correlation between the gas production rate and flowback rate for shale gas wells. Surprisingly, a phenomenon that a low flowback rate of HFF usually yields a high gas production rate is found recently by field data studies. In this case, the authors investigated the reasons for this abnormal phenomenon and believed that reducing the flowback rate of HFF in a shale gas reservoir could be a new strategy for dealing with the injected HFF. Therefore, a new concept called zero flowback rate (ZFR) of HFF is put forward to serve as an unconventional way to manage the high volume of HFF. ZFR of HFF is a concept compared with the flowback rate of the fracturing fluid for a conventional reservoir. It is worth noting that zero in the ZFR concept does not stand for the absolute number 0. It means that reducing the flowback rate of HFF is the goal of the ZFR strategy. To analyze the feasibility of realizing ZFR, the geological conditions of gas shale and engineering conditions of hydraulic fracturing were evaluated by comparing the relative studies. It showed that gas shale has the potential to imbibe most of the HFF and retain the imbibed fluid without contaminating the groundwater. ZFR can be realized by extending the shut-in time or adjusting the properties of HFF. Compared with the conventional idea of increasing the flowback rate of HFF, ZFR is of great significance. It does not only recover the relative gas permeability of the shale reservoir by redistributing the liquid phase from the fractures into the shale matrix but also enhances it by creating new microfractures. ZFR is cost-saving and environmentally friendly by dealing with a reduced volume of flowback HFF. ZFR has a high potential of becoming a viable strategy for the development of shale gas reservoirs.

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Impact of Flowback Dynamics on Fracture Conductivity

Cited by 32 publications

References 28 publications

Pore-Scale Study of Wettability Alteration and Fluid Flow in Propped Fractures of Ultra-Tight Carbonates

Pore-Scale Study of Wettability Alteration and Fluid Flow in Propped Fractures of Ultra-Tight Carbonates

Coupling characteristics of creep fracture of rock foundation on wind turbine under wind induced vibration

Zero Flowback Rate of Hydraulic Fracturing Fluid in Shale Gas Reservoirs: Concept, Feasibility, and Significance

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