Direct simulation of fluid-solid mechanics in porous media using the discrete element and lattice-Boltzmann methods

Journal ArticleA detailed understanding of the coupling between fluid and solid mechanics is important for understanding many processes in Earth sciences. Numerical models are a popular means for exploring these processes, but most models do not adequately handle all aspects of this coupling. This paper presents the application of a micromechanically based fluid-solid coupling scheme, lattice-Boltzmann discrete element method (LBDEM), for porous media simulation. The LBDEM approach couples the lattice-Boltzmann method for fluid mechanics and a discrete element method for solid mechanics. At the heart of this coupling is a previously developed boundary condition that has never been applied to coupled fluid-solid mechanics in porous media. Quantitative comparisons of model results to a one-dimensional analytical solution for fluid flow in a slightly deformable medium indicate a good match to the predicted continuum-scale fluid diffusion-like profile. Coupling of the numerical formulation is demonstrated through simulation of porous medium consolidation with the model capturing poroelastic behavior, such as the coupling between applied stress and fluid pressure rise. Finally, the LBDEM model is used to simulate the genesis and propagation of natural hydraulic fractures. The model provides insight into the relationship between fluid flow and propagation of fractures in strongly coupled systems. The LBDEM model captures the dominant dynamics of fluid-solid micromechanics of hydraulic fracturing and classes of problems that involve strongly coupled fluid-solid behavior

Simulation of sedimentary rock deformation: lab-scale model calibration and parameterization

Journal ArticleUnderstanding the mechanical behavior of rock is critical for researchers and decision-makers in fields from petroleum recovery to hazardous waste disposal. Traditional continuum-based numerical models are hampered by inadequate constitutive relationships governing fracture initiation and growth. To overcome limits associated with continuum models we employed a discrete model based on the fundamental laws of contact physics to calibrate triaxial tests. Results from simulations of triaxial compression tests on a suite of sedimentary rocks indicate that the basic physics of rock behavior are clearly captured. Evidence for this conclusion lie in the fact that one set of model parameters describes rock behavior at many confining pressures. The use of both inelastic and elastic parameters for comparison yields insight concerning the uniqueness of these models. These tests will facilitate development and calibration of larger scale discrete element models, which may be applied to a wide range of geological problems

Spatially-Resolved Integrated Precipitation-Surface-Groundwater Water Isotope Mapping From Crowd Sourcing: Toward Understanding Water Cycling Across a Post-glacial Landscape

Isotopic analyses of delta O-18 and delta H-2 of water in the context of the hydrologic cycle have allowed hydrologists to better understand the portioning of water between the different water domains. Isoscapes on a large spatial scale have been created to show isotopic variation in waters as a function of elevation, temperature, distance to coast, and water vapor source. We present the spatial and temporal isotopic results of precipitation, surface water, and groundwater of an ongoing study across Massachusetts, USA in order to establish an isotopic baseline for the region. This represents one of the most comprehensive and detailed isotopic studies of water across a 10,000 sq mi area that has exhaustively sampled important components of the terrestrial hydrologic cycle (precipitation, groundwater, and surface waters). We leverage the support of volunteers and citizen scientists to crowd source samples for isotopic analysis. The database consists of water samples from 14 precipitation sites, 409 ground water sites and 516 surface water sites across the state of Massachusetts, USA. The results indicate that groundwater isotopic composition ranges from delta O-18 -11 to -4 parts per thousand surface water ranges from delta O-18 -13 to -3.84 parts per thousand and precipitation ranges from delta O-18 -17.88 to -2.89 parts per thousand. On a first order, the small bias of mean groundwater (-8.7 parts per thousand) and surface water (-8.0 parts per thousand) isotopes compared to precipitation delta O-18 (-7.6 parts per thousand) supports that groundwater recharge and surface water storage effects through the hydrologic year impact the isotopic composition of surface and groundwater. While differences are distinct, they are larger than previously reported values, but still suggest more importance of summer precipitation than previously acknowledged. On average seasonal amplitudes of precipitation (2.7 parts per thousand), surface water (1.13 parts per thousand), and groundwater (similar to 0 parts per thousand) of the region demonstrate young water fractions of surface water to be 40% with groundwater similar to 0%. Results demonstrate that mean delta O-18 in precipitation, surface water and groundwaters are more enriched in heavy isotopes in areas near the coast, than the interior and western portion of Massachusetts. The hope is for this dataset to become an important tool for water management and water resource assessment across the region

Determination of stress state in deep subsea formation by combination of hydraulic fracturing in situ test and core analysis: A case study in the IODP Expedition 319

[1] In situ test of hydraulic fracturing (HF) provides the only way to observe in situ stress magnitudes directly. The maximum and minimum horizontal stresses, SHmax and Shmin, are determined from critical borehole pressures, i.e., the reopening pressure Pr and the shut-in pressure Ps, etc, observed during the test. However, there is inevitably a discrepancy between actual and measured values of the critical pressures, and this discrepancy is very significant for Pr. For effective measurement of Pr, it is necessary for the fracturing system to have a sufficiently small compliance. A diagnostic procedure to evaluate whether the compliance of the employed fracturing system is appropriate for SHmax determination from Pr was developed. Furthermore, a new method for stress measurement not restricted by the system compliance and Pr is herein proposed. In this method, the magnitudes and orientations of SHmax and Shmin are determined from (i) the cross-sectional shape of a core sample and (ii) Ps obtained by the HF test performed near the core depth. These ideas were applied for stress measurement in a central region of the Kumano fore-arc basin at a water depth of 2054?m using a 1.6?km riser hole drilled in the Integrated Ocean Drilling Program (IODP) Expedition 319. As a result, the stress decoupling through a boundary at 1285?m below seafloor was detected. The boundary separates new upper layers and old lower ones with an age gap of ~1.8?Ma, which is possibly the accretionary prism. The stress state in the lower layers is consistent with that observed in the outer edge of accretionary prism

Hydroclimatological Patterns and Limnological Characteristics of Unique Wetland Systems on the Argentine High Andean Plateau

High-elevation wetlands in South America are not well described despite their high sensitivity to human impact and unique biodiversity. We describe the hydroclimatological and limnological characteristics of 21 wetlands on the High Andean Plateau of Argentina, synthesizing information gathered over ten years (2010–2020). We collected physical-chemical, phytoplankton, and zooplankton data and counted flamingos in each wetland. We also conducted an extensive analysis of climatic patterns and hydrological responses since 1985. These wetlands are shallow, with a wide range of salinity (from fresh to brine), mostly alkaline, and are dominated by carbonate and gypsum deposits and sodium-chloride waters. They tend to have high nutrient concentrations. Plankton shows a low species richness and moderate to high dominance of taxa. Flamingos are highly dependent on the presence of Bacillariophyta, which appears to be positively linked to silica and soluble reactive phosphorus availability. Climatic conditions show a strong region-wide increase in average air temperature since the mid-1980s and a decrease in precipitation between 1985–1999 and 2000–2020. These high-elevation wetlands are fundamentally sensitive systems; therefore, having baseline information becomes imperative to understanding the impact of climatic changes and other human perturbations. This work attempts to advance the body of scientific knowledge of these unique wetland systems

Hydroclimatological patterns and limnological characteristics of unique wetland systems on the argentine high andean plateau

High-elevation wetlands in South America are not well described despite their high sensitivity to human impact and unique biodiversity. We describe the hydroclimatological and limnological characteristics of 21 wetlands on the High Andean Plateau of Argentina, synthesizing information gathered over ten years (2010?2020). We collected physical-chemical, phytoplankton, and zooplankton data and counted flamingos in each wetland. We also conducted an extensive analysis of climatic patterns and hydrological responses since 1985. These wetlands are shallow, with a wide range of salinity (from fresh to brine), mostly alkaline, and are dominated by carbonate and gypsum deposits and sodium-chloride waters. They tend to have high nutrient concentrations. Plankton shows a low species richness and moderate to high dominance of taxa. Flamingos are highly dependent on the presence of Bacillariophyta, which appears to be positively linked to silica and soluble reactive phosphorus availability. Climatic conditions show a strong region-wide increase in average air temperature since the mid-1980s and a decrease in precipitation between 1985?1999 and 2000?2020. These high-elevation wetlands are fundamentally sensitive systems; therefore, having baseline information becomes imperative to understanding the impact of climatic changes and other human perturbations. This work attempts to advance the body of scientific knowledge of these unique wetland systems.Fil: Frau, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Moran, Brendan J.. University of Massachusetts-Amherst; Estados UnidosFil: Arengo, Felicity. American Museum of Natural History; Estados UnidosFil: Marconi, Patricia. Fundación Yuchan; ArgentinaFil: Battauz, Yamila Soledad. Universidad Autonoma de Entre Rios; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Mora, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Manzo, Ramiro Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Mayora, Gisela Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Boutt, David F.. University of Massachusetts-Amherst; Estados Unido

Predicting hydraulic tensile fracture spacing in strata-bound systems

AbstractA model is presented which predicts the spacing of tensile-fractures due to fluid pressure increase in a multilayered sedimentary sequence comprising different typical sedimentary deposits such as mudstones, siltstones and sandstones. During normal burial and tectonic conditions, strata will undergo both extensional forces and an increase in fluid pressures. This model addresses the effects of the diffuse fluid pressure increase, and is useful for engineered applications such as the injection of fluid into a reservoir that may cause an increase of fluid pressure beneath a caprock, and for sedimentary sequences during normal digenetic processes of burial and fault activation. Analytical and numerical elastic stress strain solutions are compared to provide a robust normalised standard relationship for predicting the spacing of fractures. Key parameters are the local minimum horizontal stress, variability of the tensile strengths of the layers of a sedimentary sequence and the thickness of the beds. Permeability and storage are also shown to affect the fracture spacing. The model predicts many of the field observations made regarding strata-bound fracture systems, and should also prove useful in consideration of the impact of raised reservoir fluid pressures on caprock integrity

The essential value of long-term experimental data for hydrology and water management

We would like to thank the European Research Council ERC for funding the VeWa project and most of Tetzlaff's time (project GA 335910 VeWa). No data were used in producing this manuscript.Peer reviewedPublisher PD

Operational Review of the First Wireline In Situ Stress Test in Scientific Ocean Drilling

Scientific ocean drilling’s first in situ stress measurement was made at Site C0009A during Integrated Ocean Drilling Program (IODP) Expedition 319 as part of Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Stage 2. The Modular Formation Dynamics Tester (MDT, Schlumberger)wireline logging tool was deployed in riser Hole C0009A to measure in situ formation pore pressure, formation permeability (often reported as mobility=permeability/viscosity), and the least principal stress (S3) at several isolated depths (Saffer et al., 2009; Expedition 319 Scientists, 2010). The importance of in situ stress measurements is not only for scientific interests in active tectonic drilling, but also for geomechanical and well bore stability analyses. Certain in situ tools were not previously available for scientific ocean drilling due to the borehole diameter and open hole limits of riserless drilling. The riser-capable drillship, D/V Chikyu,now in service for IODP expeditions, allows all of the techniques available to estimate the magnitudes and orientations of 3-D stresses to be used. These techniques include downhole density logging for vertical stress, breakout and caliper log analyses for maximum horizontal stress, core-based anelastic strain recovery (ASR, used in the NanTroSEIZE expeditions in 2007–2008), and leak-off test (Lin et al., 2008) and minifrac/hydraulic fracturing (NanTroSEIZE Expedition319 in 2009). In this report, the whole operational planning process related to in situ measurements is reviewed, and lessons learned from Expedition 319 are summarized for efficient planning and testing in the future

A DEM model for visualising damage evolution and predicting failure envelope of composite laminae under biaxial loads

A two dimensional particle model based on the discrete element method (DEM) is developed for micromechanical modelling of fibre reinforced polymer (FRP) composite laminae under biaxial transverse loads. Random fibre distribution within a representative volume element (RVE) is considered for the micromechanical DEM simulations. In addition to predicting the stress-strain curves of the RVEs subjected to transverse compression and transverse shear stresses against the experimental testing results and other numerical modelling results, the DEM model is also able to capture the initiation and propagation of all micro damage events. Fibre distribution is found to more significantly influence the ultimate failure of composite laminae under transverse shear, while it has much less effect on the failure under transverse compression. The failure envelope of composite laminae under biaxial transverse compression and transverse shear is predicted and compared with Hashin and Puck failure criteria, showing a reasonable agreement. The predicted failure envelope is correlated with the damage evolution and the quantitative analysis of failure events, which improves the understanding of the failure mechanisms