Derek Elsworth

Derek Elsworth
Pennsylvania State University | Penn State

About

653
Publications
94,661
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18,202
Citations
Citations since 2017
264 Research Items
12406 Citations
201720182019202020212022202305001,0001,5002,0002,500
201720182019202020212022202305001,0001,5002,0002,500
201720182019202020212022202305001,0001,5002,0002,500
201720182019202020212022202305001,0001,5002,0002,500

Publications

Publications (653)
Article
Coal permeability is significantly affected by the multi-scale pore-fracture size distribution. More importantly, the pore-fracture size is changed by the effective stress, swelling/shrinkage under the influence of gas sorption, and different flow mechanisms. In conventional dual-porosity models, these effects are normally studied separately and th...
Article
Full-text available
Fluid injection-triggered seismicity has increased dramatically over the last decade with elevated pore fluid pressures acting as a prime culprit. Thus, understanding the effect of pore fluid pressure on the mechanical and hydrologic behavior of fractures and faults will illuminate the contributing and dominant physical processes. We present concur...
Preprint
We exploit nonlinear elastodynamic properties of fractured rock to probe the micro-scale mechanics of fractures and understand the relation between fluid transport and fracture aperture and area, stiffness proxy, under dynamic stressing. Experiments are conducted on rough, tensile-fractured Westerly granite specimen subject to triaxial stresses. Fr...
Article
Water diffusivity in cracked rocks is of great importance in the recovery of conventional and unconventional resources and in the sequestration of carbon dioxide and nuclear wastes. However, the mechanism of water diffusivity is not clearly revealed in the unsaturated fractured sandstone due to the limitation of accurately identifying the dynamic w...
Article
Full-text available
Predicting the evolution of permeability accurately during stimulation at the reservoir scale and at the resolution of individual fractures is essential to characterize the fluid transport and the reactive/heat-transfer characteristics of reservoirs where stress exerts significant control. Here, we develop a hybrid machine learning (ML) model to vi...
Article
Injecting proppant to prop open fluid-driven fractures in subsurface reservoirs is one of the key missions of hydraulic fracturing. However, quantitative evaluation of the distribution of successfully propped fractures is limited due to the infeasibility of direct measurement. This work defines an indexing parameter for field practice to estimate t...
Article
Full-text available
Acoustic travel times through Green River shale samples both parallel and perpendicular to bedding are measured to investigate water interactions with Green River shale and the impact of pertinent factors including exposure durations, pore pressure, effective stress, and anisotropy. To assist these analyses, X-ray diffraction (XRD) and permeability...
Article
The evolution of coal permeability is very complex under the influence of coupled multiple processes. This is the primary motivation why numerous coal permeability models have been developed over the last decades. Although great efforts have been made to evaluate these models, the root causes of discrepancies between lab/field observations and mode...
Article
Whether the gas in kerogen is liberated/sealed by water, is a crucial issue for successful shale gas reservoir exploitation. Although this issue has been recognized, no tools are developed to evaluate the impact of this gas liberation/sealing on gas production under in-situ conditions. In this work, a concept named kerogen threshold differential pr...
Article
An unusual increase in seismicity rate near the development and production sites of unconventional energy (e.g., natural gas and geothermal fluids) has been attributed to subsurface fluid injection. Damaging and hazardous earthquakes in many countries (e.g., China, South Korea, and the United States) have motivated tremendous effort to understand t...
Article
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Microearthquakes accompanying shale gas recovery highlight the importance of exploring the frictional and stability properties of shale gouges. Aiming to reveal the influencing factors on fault stability, this paper explores the impact of mineral compositions, effective stress and temperature on the frictional stability of Longmaxi shale gouges in...
Article
Microearthquakes accompanying shale gas recovery highlight the importance of exploring the frictional and stability properties of shale gouges. Aiming to reveal the influencing factors on fault stability, this paper explores the impact of mineral compositions, effective stress and temperature on the frictional stability of Longmaxi shale gouges in...
Article
Full-text available
Fluids injection for hydraulic stimulation and fracturing, typical in the development of enhanced geothermal systems (EGS) in granites, can reactivate deep faults and induce seismicity. Such faults typically contain chlorite coatings as an alteration product that may impact styles of deformation—aseismic through seismic. We performed low velocity s...
Conference Paper
With the continuous depth breakthrough of two ultra-deep exploration wells in northeastern Sichuan block, tuff reservoir was finally discovered at the depth of 6700-7300 m. It belongs to ultra-deep tight gas reservoir with low brittle mineral content and high clay content. Hydraulic fracturing is hard to be reformed this special reservoir, easy to...
Conference Paper
We investigate controls on fluid transfer into massive hydraulic fractures due to reactivation of, and proppant penetration into, oblique fractures transecting the main fracture face during long-term reservoir depletion through tightly constrained laboratory experiments. Permeability evolution of fracture-contained proppant permeability/conductivit...
Article
Full-text available
We investigate the evolution of` fracture conductivity as a function of proppant loading concentration under varying effective stresses as an analog to reservoir drawdown. In particular, we define the relative impacts and interactions between proppant crushing, proppant embedment, compaction and particle rearrangement and their impacts on fluid tra...
Article
The fractal particle size distribution (PSD) theory is used to characterize the particles produced in shale drilling.Fractal dimension comprehensively reflects the characteristic particle size and features of the distribution of the drilling PSD.Wear effect produces nano-particles with a volume of ~1.88–3.76% during the particles transport process...
Article
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Nonlinear elastodynamic response of fractured rocks carries crucial information on fracture features that can be exploited to forecast flow properties, friction constitutive behavior and poromechanical response. Well-controlled laboratory experiments are designed to measure the nonlinear elastodynamic response of Westerly granite in three states: d...
Article
Full-text available
Microbially-induced calcium carbonate precipitation (MICP) is a promising grouting material for subsurface remediation due to its water-like viscosity and excellent penetration. Current studies of MICP-grouting for subsurface remediation of both rock fractures and highly-permeable rock matrix focus on the spatio-temporal distribution of precipitate...
Article
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Mechanical properties of shales are key parameters influencing hydrocarbon production – impacting borehole stability, hydraulic fracture extension and microscale variations in in situ stress. We use Ordovician shale (Sichuan Basin, China) as a type-example to characterize variations in mineral particle properties at microscale including particle mo...
Article
We build a model to determine sorptive permeability loss from observed total permeability evolution by considering adsorption and poromechanical expansion as parallel processes. The model is cross verified with a separately derived strain-based model for sorptive permeability evolution. Both models are compared to laboratory data and are shown to h...
Article
A deep understanding of the process of coalbed methane (CBM) extraction is of significance for both the unconventional energy supply and mine safety. The effects of stimulation patterns and thermal effects (including thermal shrinkage, non-isothermal sorption, and gas density change) significantly affect the CBM extraction process. Although thermal...
Article
Full-text available
The presence of metamorphic epidote on faults has been implicated in the transition from stable to unstable slip and the nucleation of earthquakes. We present structured laboratory observations of mixed epidote and simulated Pohang granodiorite (analogous to the EGS‐enhanced geothermal system site) gouges to evaluate the impact of heterogeneity and...
Article
Optimization of fracturing perforation is of great importance to the commingling gas production in coal measure strata. In this paper, a 3D lattice algorithm hydraulic fracturing simulator was employed to study the effects of perforation position and length on hydraulic fracture propagation in coal measures of the Lin-Xing block, China. Based on fi...
Article
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Conventional dual porosity/permeability models for coal cannot capture the true transient nature of matrix-fracture mechanical interactions because these interactions are normally characterized through two equilibrium systems within the same REV (representative elementary volume). In this study, the transient process in the matrix system is include...
Article
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Understanding the propagation of hydraulic fractures (HF) and their interaction with pre-existing fractures is essential in conducting effective stimulation in naturally fractured reservoirs. We explore fracture propagation within an equivalent continuum represented by linear elastic fracture mechanics, while updating the equivalent composite modul...
Article
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Microbially-induced calcium carbonate precipitation (MICP) can enhance the stiffness and bulk strength of sand aggregates via calcium carbonate cementation. This study explores the mechanical strength of silica sand aggregates with different particle morphologies and sizes following MICP treatment. Specifically, unconfined uniaxial compressive stre...
Article
Sand screenout is one of the most serious and frequent challenges that threaten the efficiency and safety of hydraulic fracturing. Current low prices of oil/gas drive operators to control costs by using lower viscosity and lesser volumes of fluid for proppant injection—thus reducing the sand-carrying capacity in the treatment and increasing the ris...
Preprint
Full-text available
Fracturing controls rates of mass, chemical and energy cycling within the crust. We use observed locations and magnitudes of microearthquakes (MEQs) to illuminate the evolving architecture of fractures reactivated and created in the otherwise opaque subsurface. We quantitatively link seismic moments of laboratory MEQs to the creation of porosity an...
Article
In a coal reservoir, matrix shrinkage caused by gas desorption is regarded as a significant factor that can influence natural fracture permeability. It is considered to be a constant and lasting effect throughout coalbed methane (CBM) production based on previous investigations. However, experimental measurements of long-term permeability change ha...
Article
Full-text available
Heat production from geothermal reservoirs is a typical heat transfer process involving a cold working fluid contacting a hot rock formation. Compared to the thermal-physical characteristics of water, super-critical CO 2 (scCO 2) has a higher heat storage capacity over a wide temperature-pressure range and may be favored as a heat transfer fluid. S...
Article
Dynamic monitoring of the internal fluid distribution during CO2 immiscible/miscible flooding provides a crucial window for illuminating key processes controlling displacement and transport. We used online low-field nuclear magnetic resonance (NMR) imaging to monitor CO2 flooding under different reservoir pressures in low-permeability siltstone cor...
Article
Grain texture characteristics play vital roles in modulating the anisotropy, strength, and ductility of crystalline rock. Grain textures (shape, size, orientation and heterogeneity) are a key parameter controlling response but are challenging to incorporate in a quantitative manner. We propose and incorporate a grain texture model (GTM) into granul...
Article
Fracturing fluid filtrate that leaks off during injection is imbibed by strong capillary forces present in low-permeability sandstones and may severely reduce the effective gas permeability during cleanup and post-fracture production. This work aims to investigate the role fracturing fluid filtrate from slickwater has on rock-fluid and fluid-fluid...
Article
To effectively drain gas from coal seam, many technologies have been developed to fracture the coal which in turn to release the formation stress and increase permeability and finally achieve the desired gas drainage. CO2 gas fracturing is a newly developed technique for coal seam stimulation towards effective gas drainage. This technique can provi...
Article
Adsorption of gases such as methane and carbon dioxide in coal is an exothermic process. Under isentropic conditions (fully insulated condition), the ejected heat results in an additive transient thermal expansion in addition to the sorption-induced swelling. The magnitude of thermal expansion and its feedback on methane adsorption remains ill-defi...
Article
Fault damage zones potentially represent native permeable channels within otherwise ultra-tight igneous formations that may be used to promote fluid circulation for convective heat recovery. The United Downs Deep Geothermal Power (UDDGP) project aims to recover geothermal energy by directly injecting, circulating then recovering fluids from such a...
Article
Fluid injection into a rock mass from industrial processes can cause perceivable seismic events that may raise public concern. This seismicity can be caused by injection-induced fluid pressure in the rock mass causing slip on faults. Here we provide a method to distinguish between aseismic and seismic mobilisation and to predict fault movement due...
Article
A coupled THMC (thermal-hydrological-mechanical-chemical) model is developed and applied to explore the potential feasibility of using scCO2 (supercritical carbon dioxide) as a working fluid in geothermal reservoirs. This is achieved by examining the evolution of the kinetics of mineral precipitation-dissolution and its associated impact on the evo...
Article
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We describe laboratory experiments to elucidate the relationship between nonlinear elasticity and permeability evolution in fractured media subjected to local stress perturbations. This study is part of an effort to measure fluid pathways and fracture properties using active‐source acoustic monitoring during fluid injection and shear of rough fract...
Article
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Microwave irradiation is widely applied as a heating method since this approach avoids the intrinsic limitations of heat transfer via conduction. However, microwave heating in highly heterogeneous materials, such as rocks, remains poorly understood. Current approaches applied to rocks typically ignore (i) state transformations of liquid and solid,...
Article
The complex interaction between fluids and solids in reservoirs includes interface slip, capillary confinement and the diffusion and mass transfer between CO2 and oil and results in intensely nonlinear flow complexity. This study proposes a relative permeability model that accommodates a fractal pore size distribution and honors these complex proce...
Conference Paper
The process of extracting coalbed methane (CBM) is not only of significance for unconventional energy supply but also important in mine safety. The recent advance in fracking techniques, such as carbon dioxide (CO2) fracking, intensifies the complexity of stimulated coalbeds. This work focuses on developing a fully coupled multidomain model to desc...
Article
Full-text available
The possibility of controlling induced earthquake magnitude through managed metering of water injection has yet to be rationalized. Mechanisms of reducing magnitudes of induced events through cycled fluid injection remain unclear. To explore such mechanisms and this possibility, we report experiments with water injection into laboratory faults. Wat...
Article
Full-text available
Utilizing underground coal gasification cavities for carbon capture and sequestration provides a potentially economic and sustainable solution to a vexing environmental and energy problem. The thermal influence on creep properties and long-term permeability evolution around the underground gasification chamber is a key issue in UCG-CCS operation in...
Article
We explore the impact of thermally induced desorption on permeability evolution in shale at constant pore pressure. Permeability loss due to thermal expansion of mineral aggregates competes with permeability enhancement due to thermal desorption and shrinkage with increasing temperature. In experiments using core plugs of Marcellus shale, permeabil...
Article
The permeability of the coal reservoir is affected by the stress caused by water production and matrix shrinkage caused by methane desorption, and its change rate is mainly affected by the elastic parameters of coal, namely Young's modulus (E) and Poisson's ratio (v). E and v will change with the change of coal water saturation, which will affect t...
Article
Micropores (<2 nm) are commonly well developed in shale kerogen, which plays an important role for generation and transport of gas in shales. However, the mechanism of micropores development in kerogen structure has not been fully investigated. In this study, we provide an improved methodology to construct 3-D models of kerogen structure, then we c...
Article
Full-text available
Gas adsorption/desorption can result in swelling/shrinking of the matrix in fractured shale. The significant contrast in permeability between fractures and matrix results in an extended duration for the equilibration of the gas injection or depletion-created pressure difference. This spatially non-uniform pressure dissipation induces non-uniform de...
Article
Hydrofractured shale reservoirs exhibit a complex hierarchy of heterogeneous structures. Although the importance of hierarchical structures has long been recognised, the full control of scale-dependent heterogeneities on gas production remains ill-defined. We characterize reservoir structural heterogeneity at four hierarchical levels: (1) heterogen...
Article
Discriminating methane mass stored between free and adsorbed states in coal and shale is crucial in devising optimal gas recovery strategies and greenhouse control. Existing methods of estimating free and adsorbed gas contents in core plugs cannot fully discriminate between methane phases due to high levels of compaction and the resulting complex a...
Article
Commercial production of coal seam gas is a significant proportion of the total Worldwide natural gas supply due to its high gas storage capacity at shallow extraction depths. Coal seam gas recovery may be enhanced by pure fluid-based or proppant based hydraulic fracturing-the decision whether or not to use proppants depends on coal seam characteri...
Article
Full-text available
Geothermal and volcanic areas are prone to earthquake triggering1,2. The Coso geothermal field in California lies just north of the surface ruptures driven by the 2019 Ridgecrest earthquake (moment magnitude Mw = 7.1), in an area where changes in coseismic stress should have triggered aftershocks3,4. However, no aftershocks were observed there⁴. He...
Article
This review study aims to identify why current experimental measurements of shale permeability are not consistent with predictions of commonly-used permeability models and explore how the identified reason would guide future research. These goals are achieved through the collection of experimental permeability measured under constant confining pres...
Article
Gas transport in coal induces effective stress variation, matrix swelling/shrinkage, and significantly affects matrix and fracture deformation, resulting in porosity and permeability evolution. However, the heterogeneity and anisotropy of coal are neglected in dual porosity models, which can lead to the deviation from the real physical mechanisms....
Article
Proppants hold fractures open and increase fracture conductivity but must survive and remain functional during pressure drawdown. The shale reservoir usually suffers a high effective stress during gas depletion whilst most previous experiment works are conducted under a relative low stress level. In this work, permeability evolution was explored in...
Article
Full-text available
Plain Language Summary Fluid injection into EGS (enhanced geothermal systems) reservoirs can reactivate subsurface faults and trigger earthquakes. To understand the influence of fluid injection to earthquake triggering on deep faults we analyzed the frictional properties of simulated faults containing the alteration minerals epidote (Ep) and chlori...
Article
Nanopore/subnanopore networks comprising tight reservoirs exhibit special behaviors in the storage and transport of capillary-confined fluids. We develop a hydro-mechanical-chemical model coupling the response of capillary-confined phase behavior, multicomponent flow, reservoir deformation and reaction-controlled porosity evolution to explore the e...
Article
Microwave heating fracturing is potentially a green stimulation technology for gas shale recovery. However, the mechanism together with permeability evolution of microwave irradiated reservoir remain unclear. To fill this knowledge gap, the responses of Longmaxi shale from the Sichuan Basin, southwest China, to both continuous and intermittent micr...
Article
Characterization of CO2 flow in propped fractures is important in defining the response to CO2 injection for reservoir stimulation and CO2 sequestration. We measure the evolution of permeability in propped fractures of shale to both adsorbing CO2 and non-adsorbing He under sub- and super-critical conditions. A tripartite permeability-pressure evolu...
Article
Swarms of earthquakes during shale gas exploitation in the Changning area of Sichuan Basin indicate that hydraulic fracturing induces seismicity both within the target reservoir but also to depths of several kilometers below the horizontal well. These remote earthquakes are possibly triggered by total stress perturbations resulting from the hydraul...
Article
Full-text available
Microwave-assisted rock fracturing has been widely applied to satisfy increasing demands for safety, high efficiency and energy saving. During microwave irradiation, rock damage occurs as a result of the irregular distribution of induced temperatures and resulting thermal stresses. This non-uniform temperature distribution may develop from either (...
Article
CO2 fracturing is one potential technique to relieve environmental issues related to the massive hydraulic fracturing of hydrocarbon reservoirs. We summarize fundamental studies on overall procedures of CO2 fracturing and analyze research progress related to fracturing, the propping of the induced fractures and permeating CO2 into, then recovering...
Article
We probe mechanisms controlling the nonlinear elastodynamic response of intact and fractured rock under both fluid-saturated and dry conditions. We present the results of dynamic acoustoelastic testing (DAET) on Westerly granite in three states: dry-intact, dry-fractured and saturated-fractured to study the influence of in-situ stress, fracture and...
Article
In conventional dual porosity models, the interactions between matrix and fractures are normally characterized through two equilibrium systems within the same REV (representative elementary volume). This pseudo-steady approach cannot capture the true impact of the non-equilibrium period within each system since it ignores the true transient nature...
Article
Coal and gas outbursts are a violent release of energy in part driven by rapidly desorbing gas from the fragmenting coal. We present a coupled two-phase model of coal and gas outbursts to define the timing, rate and magnitude of gas desorption and its contribution to the resulting energetics. The model involves a fragmenting ejection of the outburs...