The Experts below are selected from a list of 25635 Experts worldwide ranked by ideXlab platform
Nima Shokri - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of foam flow in a rock Fracture: Effects of aperture variation on apparent shear viscosity and bubble morphology
Journal of colloid and interface science, 2019Co-Authors: Mohammad Javad Shojaei, Yves Méheust, Antonio Rodríguez De Castro, Nima ShokriAbstract:There has recently been renewed interest in understanding the physics of foam flow in permeable media. As for Newtonian flows in Fractures, the heterogeneity of local apertures in natural Fractures is expected to strongly impact the spatial distribution of foam flow. Although several experimental studies have been previously performed to study foam flow in Fractured media, none of them has specifically addressed that impact for parallel flow in a realistic Fracture Geometry and its consequences for the foam's in situ shear viscosity and bubble morphologies. To do so, a comprehensive series of single-phase experiments have been performed by injecting pre-generated foams with six different qualities at a constant flow rate through a replica of a Vosges sandstone Fracture of well-characterized aperture map. These measurements were compared to measurements obtained in a Hele-Shaw (i.e., smooth) Fracture of identical hydraulic aperture. The results show that Fracture wall roughness strongly increases the foam's apparent viscosity and shear rate. Moreover, foam bubbles traveling in regions of larger aperture exhibit larger velocity, size, a higher coarsening rate, and are subjected to a higher shear rate. This study also presents the first in situ measurement of foam bubbles velocities in Fracture Geometry, and provides hints towards measuring the in situ rheology of foam in a rough Fracture from the velocity maps, for various imposed mean flow rates. These findings echo the necessity of considering Fracture wall when predicting the pressure drop through the Fracture and the effective viscosity, as well as in situ rheology, of the foam.
Ruihan Zhang - One of the best experts on this subject based on the ideXlab platform.
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a simulator for production prediction of multistage Fractured horizontal well in shale gas reservoir considering complex Fracture Geometry
Journal of Natural Gas Science and Engineering, 2019Co-Authors: Shengnan Chen, Ruihan Zhang, Liehui Zhang, Huiying Tang, Yulong Zhao, Keren WangAbstract:Abstract Shale gas is becoming an increasingly supplementary energy source because of its clean-burning and abundance. Economic gas production in shale requires the techniques of horizontal drilling and multistage hydraulic fracturing to create complex Fracture network (CFN). How to accurately describe the characteristics of Geometry and flow mechanisms of the CFN and select the most efficient approach for modeling are challenging. In this paper, a production forecasting model for multistage Fractured horizontal well (MFHW) with CFN in shale is proposed based on the multiple interacting continua (MINC) theory (organic/inorganic matrix, natural Fractures system) and lower-dimensional discrete Fracture network (DFN) model (hydraulic Fractures system). The model is designed to describe the unconventional flow mechanisms in shale system, such as fractal porous media and non-Darcy multiscale flow in ultra-tight matrix, ad-desorption on organic materials’ surface, rock un-consolidation within natural Fractures, high-velocity turbulent flow near well range, and multiphase behaviors. We also propose a novel hybrid control volume finite element (CVFE) and finite-difference (FD) simulation method to obtain the numerical results of the model based on the unstructured 3D tri-prisms. The accuracy of the simulator is successfully validated and sensitivity analysis of some key factors (e.g.: fractal model permeability, Langmuir volume, heterogeneities of reservoir and Fractures, well platform) are conducted to evaluate the impacts on production performance. Combing with the micro-seismic monitoring (MSM) data and engineering analyses, the DFN model is applied in Longmaxi shale formation to obtain the history matching with the field data and predict the production.
Mian Chen - One of the best experts on this subject based on the ideXlab platform.
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analysis of hydraulic Fracture initiation and vertical propagation behavior in laminated shale formation
Fuel, 2017Co-Authors: Mian ChenAbstract:Abstract The extent of hydraulic Fracture vertical propagation extent is significant in evaluating simulated reservoir volume for laminated shale reservoirs. Given that it is affected by the discontinuities (beddings, natural Fractures, and other factors), Fracture Geometry is complex in the vertical plane and is different from a simple Fracture in a homogeneous sandstone reservoir. However, the propagation mechanism of hydraulic Fracture in the vertical plane has not been well understood. To clarify this mechanism, several groups of large-scale tri-axial tests were deployed in this study to investigate the Fracture initiation and vertical propagation behavior in laminated shale formation. The influences of multiple factors on Fracture vertical propagation were studied. The results showed that hydraulic Fracture initiation and propagation displayed five basic patterns in the vertical plane of laminated shale formation. The ultimate Fracture geometries could be classified into four categories: simple Fracture, fishbone-like Fracture, fishbone-like Fracture with fissure opening, and multilateral fishbone-like Fracture network. Furthermore, the favorable geo-stress conditions for forming the complex Fracture network were as follows: vertical stress difference close to 6 MPa and vertical stress difference coefficient from 0.2 to 0.5. In addition, when q · μ -value (the product of injection rate and fracturing fluid viscosity) was roughly 3 × 10−9, a complex Fracture Geometry of fishbone-like Fracture with bedding opening was formed; however, extremely small or extremely large values were both harmful. Variable injection rate fracturing with low viscosity fracturing fluid of 3 mPa·s was proved to be an effective treatment to improve the connectivity of induced hydraulic Fracture with the discontinuities. Moreover, because of the influence of cementing strength on Fracture communication effects between hydraulic Fracture and the beddings, the overall propagation region generally displayed an ellipse in shape with beddings opening asymmetrically along two wings of the main hydraulic Fracture.
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laboratory studies of Fracture Geometry in multistage hydraulic fracturing under triaxial stresses
Chemistry and Technology of Fuels and Oils, 2017Co-Authors: Bing Hou, Mian Chen, Cheng Wan, Tengfei SunAbstract:We present the results of a laboratory experiment on multistage hydraulic fracturing using a gel solution as the fracturing fluid, utilizing a laboratory setup for simulating hydraulic fracturing under triaxial stresses. As a result of the experiment, a Fracture network was formed in a cubic rock specimen. We found that an almost planar Fracture was formed during the first fracturing stage, while a concave (bowl-shaped) Fracture was formed during the second stage. Interaction between the stress fields created by the two main hydraulic Fractures (stress interference) caused growth of secondary cracks parallel to the simulated wellbore, but in this case led to a decrease in the width of the subsequent main Fracture. We established that the penny-shaped Fracture model is more suitable for predicting the Geometry of hydraulic Fractures in horizontal wells than two-dimensional (rectangular) Fracture propagation models (the Perkins – Kern – Nordgren (PKN) model, the Khristianovic – Geertsma – de Klerk (KGD) model). Special attention needs to be paid to Fracture spacing design in multistage hydraulic fracturing in horizontal wells.
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a study to assess the stress interaction of propped hydraulic Fracture on the Geometry of sequential Fractures in a horizontal well
Journal of Natural Gas Science and Engineering, 2017Co-Authors: Wan Cheng, Mian Chen, Hui Gao, Yan Jin, Guosheng JiangAbstract:Abstract The sequential fracturing in a horizontal well has been widely used in developing the unconventional oil and gas resources. The stress interactions among the sequential Fractures have significant impacts on the Fracture Geometry (width, length and shape). One of the interacting stresses is the stress induced by the propped Fracture. The stress interaction will decrease drastically, if the hydraulic Fracture (HF) is fully closed by the confining stress. The proppant inside the HF retains the residual Fracture width after the pumping is stopped, which remains poorly understood. This paper presents a HF model, which couples the fracturing fluid flow and the HF opening, to simulate the sequential Fracture propagation in the horizontal well. In addition, a linear joint element is used to evaluate the closure when the previously created Fractures are elastically propped by the compressible proppant. The closure of the propped HF on the stress field and the Fracture Geometry are evaluated numerically using this HF model. It is found that a stiffer proppant used in previously created Fracture results in a wider HF after the pumping is stopped. A stiffer propped Fracture causes a higher interacting stress on the subsequent HF which becomes more curved with a narrower width and a higher injection pressure. The subsequently created HF has little influence on the width of previously created HF. All the HFs are curved except the first HF in sequential fracturing. This paper is helpful to understand the Geometry of the sequential Fractures and the stress interaction among them, and to design the stiffness or size of the proppant for the hydraulic fracturing technique.
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Analysis of Fracture propagation behavior and Fracture Geometry using a tri-axial fracturing system in naturally Fractured reservoirs
International Journal of Rock Mechanics and Mining Sciences, 2008Co-Authors: Jian Zhou, Mian Chen, Guangqing ZhangAbstract:Hydraulic Fracture propagation behavior and Fracture Geometry in naturally Fractured reservoirs are studied through a series of servo-controlled tri-axial fracturing experiments. Three interaction types between induced Fractures with pre-Fracture were observed. Difference of horizontal stress, angle of approach and shear strength of pre-Fracture were considered to control the Fracture propagation behavior. With increasing shear strength of these pre-Fractures, the area of arrested behavior also increased. The Geometry of hydraulic Fracture is mainly controlled by in-situ stress and natural Fractures in natural reservoir. Two hydraulic Fracture patterns were observed in different stress regimes. In a normal stress regime, it was found to cause Fractures, with interacting branches because of pre-existing Fracture. Tortuous Fractures were found along the direction of Fracture height when one of the horizontal stresses is the maximum principle stress.
Thorsten Schafer - One of the best experts on this subject based on the ideXlab platform.
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experimental and numerical investigations on the effect of Fracture Geometry and Fracture aperture distribution on flow and solute transport in natural Fractures
Journal of Contaminant Hydrology, 2019Co-Authors: Madeleine Stoll, Florian Huber, M Trumm, Frieder Enzmann, Dietmar Meinel, A Wenka, Eva Schill, Thorsten SchaferAbstract:The impact of Fracture Geometry and aperture distribution on fluid movement and on non-reactive solute transport was investigated experimentally and numerically in single Fractures. For this purpose a hydrothermally altered and an unaltered granite drill core with axial Fractures were investigated. Using three injection and three extraction locations at top and bottom of the Fractured cores, different dipole flow fields were examined. The conservative tracer (Amino-G) breakthrough curves were measured using fluorescence spectroscopy. Based on 3-D digital data obtained by micro-computed tomography 2.5-D numerical models were generated for both Fractures by mapping the measured aperture distributions to the 2-D Fracture geometries (x-y plane). Fluid flow and tracer transport were simulated using COMSOL Multiphysics®. By means of numerical simulations and tomographic imaging experimentally observed breakthrough curves can be understood and qualitatively reproduced. The experiments and simulations suggest that fluid flow in the altered Fracture is governed by the 2-D Fracture Geometry in the x-y plane, while fluid flow in the unaltered Fracture seems to be controlled by the aperture distribution. Moreover, we demonstrate that in our case simplified parallel-plate models fail to describe the experimental findings and that pronounced tailings can be attributed to complex internal heterogeneities. The results presented, implicate the necessity to incorporate complex domain geometries governing fluid flow and mass transport into transport modeling.
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natural micro scale heterogeneity induced solute and nanoparticle retardation in Fractured crystalline rock
Journal of Contaminant Hydrology, 2012Co-Authors: Frieder Enzmann, A Wenka, Thorsten Schafer, F M Huber, M Bouby, Marco DentzAbstract:Abstract We studied tracer (Tritiated Water (HTO); Tritium replaces one of the stable hydrogen atoms in the H 2 O molecule) and nanoparticle (quantum dots (QD)) transport by means of column migration experiments and comparison to 3D CFD modeling. Concerning the modeling approach, a natural single Fracture was scanned using micro computed tomography (μCT) serving as direct input for the model generation. The 3D simulation does not incorporate any chemical processes besides the molecular diffusion coefficient solely reflecting the impact of Fracture heterogeneity on mass (solute and nanoparticles) transport. Complex fluid velocity distributions (flow channeling and flowpath heterogeneity) evolve as direct function of Fracture Geometry. Both experimental and simulated solute and colloidal breakthrough curves show heavy tailing (non-Fickian transport behavior), respectively. Regarding the type of quantum dots and geochemical conditions prevailing (Grimsel ground water chemistry, QD and diorite surface charge, respectively and porosity of the Aspo diorite drill core) experimental breakthrough of the quantum dots always arrives faster than the solute tracer in line with the modeling results. Besides retardation processes like sorption, filtration, straining or matrix diffusion, the results show that natural 3D Fracture heterogeneity represents an important additional retardation mechanism for solutes and colloidal phases. This is clearly verified by the numerical simulations, where the 3D real natural Fracture Geometry and the resulting complex flow velocity distribution is the only possible process causing solute/nanoparticle retardation. Differences between the experimental results and the simulations are discussed with respect to uncertainties in the μCT measurements and experimental and simulation boundary conditions, respectively.
Mohammad Javad Shojaei - One of the best experts on this subject based on the ideXlab platform.
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Dynamics of foam flow in a rock Fracture: Effects of aperture variation on apparent shear viscosity and bubble morphology
Journal of colloid and interface science, 2019Co-Authors: Mohammad Javad Shojaei, Yves Méheust, Antonio Rodríguez De Castro, Nima ShokriAbstract:There has recently been renewed interest in understanding the physics of foam flow in permeable media. As for Newtonian flows in Fractures, the heterogeneity of local apertures in natural Fractures is expected to strongly impact the spatial distribution of foam flow. Although several experimental studies have been previously performed to study foam flow in Fractured media, none of them has specifically addressed that impact for parallel flow in a realistic Fracture Geometry and its consequences for the foam's in situ shear viscosity and bubble morphologies. To do so, a comprehensive series of single-phase experiments have been performed by injecting pre-generated foams with six different qualities at a constant flow rate through a replica of a Vosges sandstone Fracture of well-characterized aperture map. These measurements were compared to measurements obtained in a Hele-Shaw (i.e., smooth) Fracture of identical hydraulic aperture. The results show that Fracture wall roughness strongly increases the foam's apparent viscosity and shear rate. Moreover, foam bubbles traveling in regions of larger aperture exhibit larger velocity, size, a higher coarsening rate, and are subjected to a higher shear rate. This study also presents the first in situ measurement of foam bubbles velocities in Fracture Geometry, and provides hints towards measuring the in situ rheology of foam in a rough Fracture from the velocity maps, for various imposed mean flow rates. These findings echo the necessity of considering Fracture wall when predicting the pressure drop through the Fracture and the effective viscosity, as well as in situ rheology, of the foam.
