The Experts below are selected from a list of 786 Experts worldwide ranked by ideXlab platform
Derek Elsworth - One of the best experts on this subject based on the ideXlab platform.
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Swelling and embedment induced by sub- and super-critical-CO2 on the permeability of propped fractures in shale
International Journal of Coal Geology, 2020Co-Authors: Lei Hou, Derek Elsworth, Xueyu GengAbstract:Abstract Swelling and embedment exert significant influence on the evolution of permeability in propped fractures, potentially consuming significant proportions of the original gain in permeability. We measure the evolution of permeability in propped fractures of shale to both adsorbing CO2 and non-adsorbing He – accommodating the impacts of aperture change due to Proppant Pack compaction and both reversible and irreversible modes of embedment. A linear relation between pressure and log-permeability is obtained for He, representing the impact of effective stresses in Proppant Pack compaction, alone. Permeability change with pressure is always concave upwards and U-shaped for gaseous subcritical CO2 and W-shaped for supercritical CO2. One exception is for liquid CO2 at high injection pressure where effective stress effects and swelling contribute equally to the change in permeability and result in a linear curve with the lowest permeability. Approximately ~50–70% of the permeability recovers from the recovery of swelling after the desorption of CO2. The magnitude of swelling is recovered from measurements of permeability change and ranges from 0.005 to 0.06 mm, which contributes ~9–56% of the total swelling and induced embedment as evaluated from the adsorbed mass. Swelling also increases embedment by a factor of ~1.84–1.93 before and after the injection of CO2. A new calibration equation representing swelling and induced embedment is generated accommodating Langmuir isothermal sorption and verified against experiments on rocks both admitting and excluding swelling and embedment and for various sorbing and non-sorbing gases. Stability and accuracy of the predictions demonstrate the universality of the approach that may be applied to both enhanced gas recovery and CO2 sequestration.
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Propagation, Proppant transport and the evolution of transport properties of hydraulic fractures
Journal of Fluid Mechanics, 2018Co-Authors: Jiehao Wang, Derek Elsworth, Martin K. DenisonAbstract:Hydraulic fracturing is a widely used method for well stimulation to enhance hydrocarbon recovery. Permeability, or fluid conductivity, of the hydraulic fracture is a key parameter to determine the fluid production rate, and is principally conditioned by fracture geometry and the distribution of the encased Proppant. A numerical model is developed to describe Proppant transport within a propagating blade-shaped fracture towards defining the fracture conductivity and reservoir production after fracture closure. Fracture propagation is formulated based on the PKN-formalism coupled with advective transport of an equivalent slurry representing a Proppant-laden fluid. Empirical constitutive relations are incorporated to define rheology of the slurry, Proppant transport with bulk slurry flow, Proppant gravitational settling, and finally the transition from Poiseuille (fracture) flow to Darcy (Proppant Pack) flow. At the maximum extent of the fluid-driven fracture, as driving pressure is released, a fracture closure model is employed to follow the evolution of fracture conductivity with the decreasing fluid pressure. This model is capable of accommodating the mechanical response of the Proppant Pack, fracture closure of potentially contacting rough surfaces, Proppant embedment into fracture walls, and most importantly flexural displacement of the unsupported spans of the fracture. Results show that reduced fluid viscosity increases the length of the resulting fracture, while rapid leak-off decreases it, with both characteristics minimizing fracture width over converse conditions. Proppant density and size do not significantly influence fracture propagation. Proppant settling ensues throughout fracture advance, and is accelerated by a lower viscosity fluid or greater Proppant density or size, resulting in accumulation of a Proppant bed at the fracture base. ‘Screen-out’ of Proppant at the fracture tip can occur where the fracture aperture is only several times the diameter of the individual Proppant particles. After fracture closure, Proppant Packs comprising larger particles exhibit higher conductivity. More importantly, high-conductivity flow channels are necessarily formed around Proppant banks due to the flexural displacement of the fracture walls, which offer preferential flow pathways and significantly influence the distribution of fluid transport. Higher compacting stresses are observed around the edge of Proppant banks, resulting in greater depths of Proppant embedment into the fracture walls and/or an increased potential for Proppant crushing.
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experiment and modeling to evaluate the effects of Proppant Pack diagenesis on fracture treatments
Journal of Petroleum Science and Engineering, 2010Co-Authors: Dae Sung Lee, Jim D. Weaver, Derek Elsworth, Hideaki Yasuhara, Richard D. RickmanAbstract:article i nfo Article history: Observed reductions in the permeability of propped hydraulic fractures are examined by considering the role of mechanical stresses and the chemistry of pore!uids at elevated temperatures as agents of Proppant diagenesis. Stress-enhanced dissolution of Proppant increases the density of grain Packing and reprecipita- tion of mineral matter further occludes pores—together these mechanisms additively reduce porosity and permeability. Experiments and analyses are presented which explore the evolution of porosity and permeability in Proppant Packs subjected to reservoir conditions of stresses to 65 MPa and temperatures to 177 °C. Experiments are completed in two modes: in!ow-through reactors absent intergranular stresses to evaluate rates of dissolution and reprecipitation on Proppant surfaces, and in uniaxially stressed reactors with stagnant!uids to evaluate the relative role of stress in mediating dissolution and porosity reduction. Lumped parameter models are used to evaluate rates of dissolution and chemical compaction in a range of Proppants. Mechanisms include mineral dissolution, transport, and reprecipitation of the resulting products in the particle interstices, resulting in a loss of intergranular porosity. The model uses thermodynamic data derived from the reactor experiments to constrain the projected loss of permeability for the mineralogical composition of available Proppants. Evaluated silica dissolution rates vary with temperature but are of the order of 1.1 !10 !11
Mandar Chaitanya Kulkarni - One of the best experts on this subject based on the ideXlab platform.
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creating novel granular mixtures as Proppants insights to shape size and material considerations
Mechanics of Advanced Materials and Structures, 2017Co-Authors: Mandar Chaitanya Kulkarni, Ozden O OchoaAbstract:ABSTRACTFragmentation of Proppant particles in a Pack subjected to compressive loading results in a loss of load bearing capacity. Addition of ductile particles to a brittle particle Pack reduces particle fragmentation. Computational models simulating confined compression of a Proppant Pack with a mixture of brittle and ductile particles are developed. The effect of soft particle material, shape, and size on the fragmentation behavior of the brittle particle in a Proppant Pack is studied. The results showed that larger, nonuniform particles lead to higher incidence of particle fracture. More efficient Pack compositions are proposed for further study and development.
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mechanics of light weight Proppants a discrete approach
Composites Science and Technology, 2012Co-Authors: Mandar Chaitanya KulkarniAbstract:Abstract The computational and experimental assessment of light-weight Proppants are undertaken to identify their effectiveness and efficiency to replace sand enlisted in hydraulic fracturing treatments in oil or gas well operations. A mixture of ground-nut-shells, aluminum or ceramic particles are shown to reduce the viscosity of the fracturing fluid while increasing its resistance to compression. Herein explicit dynamic finite element method is implemented to study quasi-static compression of a Proppant Pack where each granule (particle) is modeled individually. Various mixtures of hard and soft particles are investigated as a function of shape, size and inter-particle friction. The particle interactions clearly illustrate changes in pore space as a function of pressure, mixture composition and friction. The pressure vs displacement response of a Proppant Pack reflects strong dependence on mixture composition and initial particle configuration and has been compared with the test data. Friction leads to higher porosity by limiting particle rearrangement. Models reveal that softer rock with a mixture of hard and soft particles inhibit flowback but may decrease the Pack permeability.
Shengqiang Yang - One of the best experts on this subject based on the ideXlab platform.
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Crushing and embedment of Proppant Packs under cyclic loading: An insight to enhanced unconventional oil/gas recovery
Geoscience Frontiers, 2020Co-Authors: K.m.a.s. Bandara, Pathegama Gamage Ranjith, Tharaka Dilanka Rathnaweera, W.a.m. Wanniarachchi, Shengqiang YangAbstract:Abstract Crushing and embedment are two critical downhole Proppant degradation mechanisms that lead to a significant drop in production outputs in unconventional oil/gas stimulation projects. These persistent production drops due to the non-linear responses of Proppants under reservoir conditions put the future utilization of such advanced stimulation techniques in unconventional energy extraction in doubt. The aim of this study is to address these issues by conducting a comprehensive experimental approach. According to the results, whatever the type of Proppant, all Proppant Packs tend to undergo significant plastic deformation under the first loading cycle. Moreover, the utilization of ceramic Proppants (which retain Proppant Pack porosity up to 75%), larger Proppant sizes (which retain Proppant Pack porosity up to 15.2%) and higher Proppant concentrations (which retain Proppant Pack porosity up to 29.5%) in the fracturing stimulations with higher in-situ stresses are recommended to de-escalate the critical consequences of crushing associated issues. Similarly, the selection of resin-coated Proppants over ceramic and sand Proppants may benefit in terms of obtaining reduced Proppant embedment. In addition, selection of smaller Proppant sizes and higher Proppant concentrations are suggested for stimulation projects at depth with sedimentary formations and lower in-situ stresses where Proppant embedment predominates. Furthermore, correlation between Proppant embedment with repetitive loading cycles was studied. Importantly, microstructural analysis of the Proppant-embedded siltstone rock samples revealed that the initiation of secondary induced fractures. Finally, the findings of this study can greatly contribute to accurately select optimum Proppant properties (Proppant type, size and concentration) depending on the oil/gas reservoir characteristics to minimize Proppant crushing and embedment effects.
Andrew R Barron - One of the best experts on this subject based on the ideXlab platform.
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assembly of porous hierarchical copolymers resin Proppants new approaches to smart Proppant immobilization via molecular anchors
Journal of Colloid and Interface Science, 2016Co-Authors: Shirin Alexander, Charles W Dunnill, Andrew R BarronAbstract:Abstract Hypothesis The assembly of temperature/pH sensitive complex microparticle structures through chemisorption and physisorption provides a responsive system that offers application as routes to immobilization of Proppants in-situ. Experiments Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) along with energy dispersive X-ray analysis (EDX) have been used to characterize a series of bi-functionalized monolayers and/or multilayers grown on alumina microparticles and investigate the reactive nature of both temperature sensitive cross-linker (epoxy resin) with the layers and pH-responsive bridging layer (polyetheramine). Findings The bifunctional acids, behaving as molecular anchors, allow for a controlled reaction with a cross-linker (resin or polymer) with the formation of networks, which is either irreversible or reversible based on the nature of the cross-linker. The networks results in formation of porous hierarchical particles that offer a potential route to the creation of immobile Proppant Pack.
Xueyu Geng - One of the best experts on this subject based on the ideXlab platform.
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Swelling and embedment induced by sub- and super-critical-CO2 on the permeability of propped fractures in shale
International Journal of Coal Geology, 2020Co-Authors: Lei Hou, Derek Elsworth, Xueyu GengAbstract:Abstract Swelling and embedment exert significant influence on the evolution of permeability in propped fractures, potentially consuming significant proportions of the original gain in permeability. We measure the evolution of permeability in propped fractures of shale to both adsorbing CO2 and non-adsorbing He – accommodating the impacts of aperture change due to Proppant Pack compaction and both reversible and irreversible modes of embedment. A linear relation between pressure and log-permeability is obtained for He, representing the impact of effective stresses in Proppant Pack compaction, alone. Permeability change with pressure is always concave upwards and U-shaped for gaseous subcritical CO2 and W-shaped for supercritical CO2. One exception is for liquid CO2 at high injection pressure where effective stress effects and swelling contribute equally to the change in permeability and result in a linear curve with the lowest permeability. Approximately ~50–70% of the permeability recovers from the recovery of swelling after the desorption of CO2. The magnitude of swelling is recovered from measurements of permeability change and ranges from 0.005 to 0.06 mm, which contributes ~9–56% of the total swelling and induced embedment as evaluated from the adsorbed mass. Swelling also increases embedment by a factor of ~1.84–1.93 before and after the injection of CO2. A new calibration equation representing swelling and induced embedment is generated accommodating Langmuir isothermal sorption and verified against experiments on rocks both admitting and excluding swelling and embedment and for various sorbing and non-sorbing gases. Stability and accuracy of the predictions demonstrate the universality of the approach that may be applied to both enhanced gas recovery and CO2 sequestration.
