Increase In Fluid Pressure Research Articles

Experimental and computational analysis of the injection-induced mechanical changes in the skin microenvironment during subcutaneous injection of biologics

Subcutaneous (SQ) injection is an effective delivery route for various biologics, including proteins, antibodies, and vaccines. However, pain and discomfort induced during SQ injection pose a notable challenge for the broader and routine use of biologics. Understanding the underlying mechanism and quantification of injection-induced pain and discomfort (IPD) are urgently needed. A crucial knowledge gap is what changes in the skin tissue microenvironment are induced by the SQ injection, which may ultimately cause the IPD. In this study, thus, a hypothesis is postulated that the injection of biologics solution through the skin tissue microenvironment induces spatiotemporal mechanical changes. Specifically, the injection leads to tissue swelling and subsequent increases in the interstitial fluid pressure (IFP) and matrix stress around the injection site, which ultimately causes the IPD. To test this hypothesis, an engineered SQ injection model is developed capable of measuring tissue swelling during SQ injection. The injection model consists of a skin equivalent with quantum dot-labeled fibroblasts, which enables the measurement of injection-induced spatiotemporal deformation. The IFP and matrix stress are further estimated by computational analysis approximating the skin equivalent as a nonlinear poroelastic material. The result confirms significant injection-induced tissue swelling and increases in IFP and matrix stress. The extent of deformation is correlated to the injection rate. The results also suggest that the size of biologics particulates significantly affects the pattern and extent of the deformation. The results are further discussed to propose a quantitative understanding of the injection-induced changes in the skin microenvironment.

Dynamic stability of slightly curved tensioned pipe conveying pressurized hot two phase fluid resting on non uniform foundation

The dynamic stability of slightly curved tensioned pipes conveying pressurized two phase fluid, under thermal loadings are investigated in this paper. Furthermore, these pipes are resting on nonuniform elastic foundations. The equation of motion of the system is derived using the extended Hamilton’s principle for open dynamic systems and considering the Euler–Bernoulli theory for slender beams. The free vibration and the effects of two phase fluid flow, geometric imperfections, thermal, tension and pressure on the pipe system resting on nonuniform foundations are investigated numerically. Three different boundary conditions (BC) are considered, namely simply-simply (SS) supported, simply-clamped (SC) supported and clamped-clamped (CC) supported. The numerical method of Finite Element was used on the partial differential equation. This method is used to accurately predict steady state natural frequency responses of a dynamical system through several numerical investigations. It was found that the stability of slightly curved pipes conveying two phase flow are significantly affected by the boundary condition. It is shown that the initial curvature term increases the critical velocities for all the nine modes considered, the increase is significant in the first and second critical velocities compared to the other modes. Initial curvature effect is more pronounced in simple supported ends. Further-more the influence of the fluid velocity, temperature, pressure and axial tension is analysed; the results show that the vibration frequency decreases when the fluid velocity, temperature, and pressure increase or the axial tension decreases, and the critical fluid velocity decreases when the temperature and pressure increase or the axial tension decreases. For the pipe on nonuniform foundation, an increased stiffness leads to an increased in the first critical velocity for all the BC. However, the pattern of the increment depends on the attachment parameter, initial curvature, and the vapour quality. Some of these results are completely absent in pipes conveying single flows.

Intra-articular administration of adrenaline plus an irrigation pump system for visibility during the arthroscopic reconstruction of multiple knee ligaments without a tourniquet.

Multiple ligament knee injuries (MLKIs) are rare but severe systemic trauma. Single surgery in the acute setting is preferred, although with an extended operation time. To avoid the complications associated with a tourniquet, we herein describe a method for visibility without a tourniquet: intra-articular administration of adrenaline plus an irrigation pump system. This is a cohort study with a level of evidence of 3. From April 2020 to February 2022, 19 patients with MLKIs were reviewed retrospectively. All patients got intra-articular administration of adrenaline plus an irrigation pump system for visibility without a tourniquet. The following parameters were assessed: visibility, range of motion, knee stability, visual analog scale (VAS) score, range of motion (ROM), Lysholm score, Tegner activity level, and International Knee Documentation Committee Subjective Knee Form (IKDC). All patients were followed up for at least 6 months. At the latest follow-up, the mean VAS score, ROM, Lysholm score, and IKDC were 1.79 ± 0.86, 121.21 ± 10.96, 88.16 ± 5.21, and 88.53 ± 5.06, respectively. The average Tegner activity level decreased significantly from preinjury to postoperation (5.16 ± 0.83 vs. 3.11 ± 0.88, P < 0.001). Of the 19 patients, 17 (89.47%) had good knee function, while only two patients (10.53%) had asymptomatic knees with positive Lachman tests. A total of 17 patients (89.47%) had good or excellent visualization during arthroscopy. Of the 19 patients, three (15.79%) required an increased fluid pressure to achieve a clear operative view. Two patients converted to tourniquet inflation due to persistent intra-articular bleeding after using shavers. The intra-articular administration of adrenaline plus an irrigation pump system is recommended as an alternative to a tourniquet to achieve a good visual field. Further evidence-based work with a larger sample is needed.

Key issues and explorations in shale gas fracturing

During volume fracturing of shale gas reservoirs, hydraulic fractures may readily communicate with natural fractures to propagate forward and induce the formations to slip along the fracture surfaces. The resulted inter-well frac-hit and casing deformation affect the safe and efficient operation of shale gas fracturing. In addition, unpropped fractures caused by small natural fracture width lead to deteriorating fracture conductivity, which in turn impacts the stimulation effect of shale gas reservoirs. This paper discusses the three key issues, i.e. inter-well frac-hit, casing deformation and unpropped microfractures, that impact the economic exploration and exploitation of shale gas, and proposes engineering prevention and control measures through literature review and research on mechanism by integrating theoretical and experimental analysis, which have been applied on site. Firstly, after clarifying the mechanism and main controlling factors of inter-well frac-hit, an evaluation model and prediction method of frac-hit based on machine learning were established. The measures for preventing and controlling inter-well frac-hit, including temporary plugging at fracture tip and shut-in of old wells, were determined after evaluation with the well-cluster fracture model. Secondly, an analysis model of casing deformation caused by fracture shear and slippage was established after stress analysis. According to the analysis of stress on casing intersected with fractures during fracturing, it is ascertained that increase of fluid pressure within natural fractures is the main factor that causes casing deformation. The methods for preventing casing deformation were proposed in terms of fracturing operation and well construction. Thirdly, the mechanism of micro-proppant migration was analyzed by integrating the model of particle migration and the transport experiment in large-scale plate, and the experiment confirms that micro-proppant can effectively improve the fracture conductivity. It is concluded after field application that the prevention and control measures proposed for inter-well frac-hit and casing deformation can mitigate frac-hit and casing deformation significantly, and micro-proppants are conducive to improving post-frac shale gas production. The measures provide a support for large-scale and economic development of deep shale gas.

The Role of Fluid Overpressure on the Fracture Slip Mechanism Based on Laboratory Tests That Stimulating Reservoir-Induced Seismicity

A critically stressed fracture will slide in response to the increase in fluid pressure inside the fracture while impounding, which will trigger induced seismicity. The mechanism of fluid overpressure is regarded as a significant factor in the reaction of the fracture slip after water diffusing. This study uses a shearing test with a cylinder of granite, with 100 mm height and 50 mm diameter, under the condition of hydraulic-mechanic (HM) coupling to figure out how fluid overpressure alters the mechanical behavior of the critically stressed fracture. The cyclic water pressurization simulates periodical impounding in the water reservoir. Results show that several slip events happen when water pressure continues to rise higher than the stable state. The change of roughness also indicates the deterioration of the fracture surface while sliding. According to the results, we conclude that the difference between inlet pressure and outlet pressure leads to an overpressure of the fracture, promoting a series of slips and induced seismicity. Hydraulic energy is introduced to explain the relationship between the input and output energy, which is also strong evidence to illustrate that fluid overpressure is a crucial mechanism in reservoir-induced seismicity.

Interaction of natural and hydraulic fractures: the impact on reservoir pressure buildup and risk of shear fault reactivation in the Upper Devonian Duvernay Formation, Fox Creek, Alberta

The interaction of natural and hydraulic fractures may facilitate lateral fluid propagation in an unconventional reservoir resulting in fast fluid pressure transmission from treatment wells to a fault zone and potential fault shear slip reactivation and associated induced seismicity. Several induced earthquakes (up to 4.1 Mw) occurred since 2013 during hydraulic fracturing of the Upper Devonian Duvernay Formation in the Western Canada Sedimentary Basin. The mechanism of lateral fluid migration in the unconventional reservoir is not well understood. The current study aims to investigate the interaction of natural fractures and hydraulic fractures for the case study in the area south of Fox Creek, where a linear zone of induced earthquakes (up to 3.9 Mw) occurred along a fault in 2015 during hydraulic fracturing of horizontal wells. We analyze the growth of hydraulic fractures in presence of natural fractures, the impact of resulting complex fracture network on fluid transmission and fluid pressure buildup around the treatment wells. Hydraulic fracture modeling (HFM), reservoir simulations and 3D coupled reservoir-geomechanical modeling are applied to match the timing of hydraulic fracture propagation and transmitted fluid pressure increase in the fault zone versus induced earthquake occurrence. HFM results are verified by microseismic clouds distribution. Reservoir simulations are validated by a history matching of fluid injection volume and bottomhole pressure data. Additional HFM simulations are carried out to optimize the pumping schedule in the studied well pad that would help to prevent hydraulic fractures reaching the fault and minimize the risk of induced seismicity.Article highlightsStress anisotropy and simulated natural fractures impact lateral growth of complex hydraulic fractures and reservoir pressure buildup.Predicted fluid pressure transmission to a fault zone results in fault dextral shear slip reactivation matching induced seismicity.Optimized pumping schedule helps to minimize risks of fault reactivation and induced seismicity while preserving overall pad performance.

The Behavior of Hydrothermal Mineralization With Spatial Variations of Fluid Pressure

AbstractIt is assumed that variable fluid pressure states in space control the spatiotemporal evolution of hydrofracture, and their responses on mineralization. In this study, mineral precipitation caused by rapid fluid pressure reduction is incorporated into a cellular automaton model to explore the effects of various spatially structured fluid pressure rates on the behavior of hydrofracture and mineralization. We explore a range of spatial structures, which vary from essentially random to strong spatial structure. In the model, fluid pressure increase induces local hydrofracture to nearest neighbors, and fluid mass is conserved among the cell affected. As the model evolves, internally connected networks merge and a correlation length is established as the system approaches the failure condition and identifies the percolation threshold. The correlation length of the internally connected network scales with the degree of spatial structure of fluid pressure increase rates, resulting in earlier arrival to the percolation threshold for strong spatial structures. At the percolation threshold, large‐scale fluid pressure reduction induces mineral precipitation and facilitate the formation of the spatially structured geochemical patterns. The degree of spatial structure of geochemical patterns correlates with the spatial structure of fluid pressure increase rates because mineral precipitation from fluid pressure reduction occurs over larger scale. The proposed model offers an intuitive and potentially important tool for understanding the role of spatially structured fluid pressure increase and reduction on hydrothermal mineralization patterns in fault‐related ore systems.

Spatio‐Temporal Evolution of Aftershock and Repeater Source Properties After the 2016 Pedernales Earthquake (Ecuador)

AbstractSubduction zones are highly heterogeneous regions capable of hosting large earthquakes. To better constrain the processes at depth, we analyze the source properties of 1514 aftershocks of the 16th April 2016 Mw 7.8 Pedernales earthquake (Ecuador) using spectral ratios. We are able to retrieve accurate seismic moments, stress drops, and P and S corner frequencies for 341 aftershocks, including 136 events belonging to families of repeating earthquakes. We find that, for the studied magnitude range (Mw 2–4), stress drops appear to increase as a function of seismic moment. They are also found to depend on their distance to the trench. This is in part explained by the increase in depth, and therefore normal stress, away from the trench. However, even accounting for the shallow depths of earthquakes, stress drops appear to be anomalously low near the trench, which can be explained by a high pore fluid pressure or by inherent properties of the medium (low coefficient of friction/low rigidity of the medium) in that region. We are also able to examine the temporal evolution of source properties thanks to the presence of repeating earthquakes. We find that the variations of source properties within repeating earthquake families are not uniform, and are highly spatially variable over most of the study area. This is not the case near the trench, however, where stress drops systematically decrease over time. We suggest that this reflects an increase in pore fluid pressure near the trench over the postseismic period.

Study on hydraulic fracture extension of volcanic formation in J230 area, Xinjiang

It is key of “network fracturing” stimulation to correctly recognize the rock failure pattern during hydraulic fracturing treatment. In this paper, basic characteristics of the Carboniferous volcanic reservoirs in J230 area of Xinjiang oilfield are overviewed. Triaxial in-situ stresses of the formation are interpreted by conventional well-logging data, and the natural fissure characteristics are interpreted by imaging well logging information, and intersection of geometry relationship between hydraulic fracture and cross natural cracks is described on approaching angle. Current experimental achievements of hydraulic fracture penetration cross or extension along natural fissure are summarized, mechanics criterion under the different action manner are established for opening and shear failure of natural fractures. Taking Carboniferous volcanic reservoir of J230 area as an example, a hydraulic fracture propagation model is obtained by calculation results under the action of hydraulic-natural cracks synergy. It is shown that the approaching angle in the formation is mainly 50°–60°, shear sliding failure will be firstly induced along natural-hydraulic fracture interface and then natural fissure will open because of going net pressure. With further increase of the net fluid pressure, hydraulic fracture propagated along the natural fissure because of tangential failure and gradually turns to the direction of maximum horizontal principal stress, which is conducive to the formation of network fractures in stimulated reservoir treatment.

How can casing deformation be prevented during hydraulic fracturing of shale gas?—A case study of the Weiyuan area in Sichuan, China

In the process of hydraulic fracturing of shale gas horizontal wells in the Weiyuan area of Sichuan, China, casing deformation (CD) is a frequent problem that has seriously affected the benefits of shale gas development and remains to be solved for many years. In this paper, based on the analyses of Multi-finger Imaging Tool-24 (MIT-24) data, microseismic data, and the relationship between CD and engineering parameters, we confirm that the wellbore morphology in all CD sections in the Weiyuan area is consistent with shear deformation characteristics and clarify the cause of all CD: hydraulic fracturing leads to increased fluid pressure in well-intersecting faults and large fractures (F-Fs), inducing their shear slip, and eventually leads to asymmetric compression on the casing by strata on both sides of F-Fs, i.e., CD. On this basis, we propose a set of methods to control (or moderate) the shear slip of F-Fs by reducing the additional fluid pressure in target F-Fs during hydraulic fracturing to prevent CD, including multi-cluster perforations, temporary plugging F-Fs and fracturing fluid flowback. We also analyze the theoretical basis, feasibility and workflow of these methods. These methods have been tested in 44 horizontal wells in the Weiyuan area, of which the result is a radical decrease in the CD rate of the single well (from 54% to 9.1%), indicating that the slip of F-Fs and the resulting CD during hydraulic fracturing can be controlled and providing a reference for the prevention of hydraulic fracturing-induced earthquakes.

Laramide crustal detachment in the Rockies: Cordilleran shortening of fluid-weakened foreland crust

ABSTRACTWhat causes previously stable continental crust in the forelands of Cordilleran orogenic systems to shorten during low-angle subduction? The National Science Foundation/EarthScope Bighorn Project combined seismic imaging of the crust and Moho with kinematic modeling of Laramide (Late Cretaceous–Paleogene) basement-involved deformation to address this question. In north-central Wyoming, asymmetrical ENE-verging upper-crustal folds are highly discordant with broader, N-trending warps in the Moho, indicating crustal detachment. Restorable cross sections of ENE-directed detachment at a depth of ~30 km, combined a smaller component of NNW–SSE shortening due to the east-narrowing shape of the crustal allochthon, can explain the anastomosing network of Laramide basement-cored arches without major deformation of the underlying mantle lithosphere.Thrust-related fold geometries and west-to-east initiation of deformation in the Laramide and Sevier thrust belts point to Cordilleran end-loading from the west. Differences between Laramide (~N65E) and plate (~N25E) convergence directions, along with the fanning of Laramide shortening directions from nearly E–W to the south to NE–SW to the north, indicate slip partitioning during end-loading west of the Rockies.Sub-horizontal detachment with a near-zero critical taper within cratonic crust suggests an extremely weak Laramide detachment zone during deformation. Analogous lower-crustal deformation in subduction forearcs is associated with slow earthquakes and slab dehydration. We hypothesize that low-angle subduction of the Farallon Plate suppressed fluid-consuming melting and corner-flow processes that characterize higher-angle subduction. This allowed subduction-generated fluids to escape upward into the overlying continental lithosphere, causing retrograde metamorphism and increased fluid pressure that facilitated crustal detachment. This hydration-based hypothesis predicts that crustal detachment will accompany major earthquakes in active analog orogens.

Fault Slip Behaviors Modulated by Locally Increased Fluid Pressure: Earthquake Nucleation and Slow Slip Events

AbstractHuge earthquakes are frequently preceded by slow slip events (SSEs) that are speculated as the precursor to regular earthquakes (REs). However, the way in which earthquakes initiate, as well as the interactions between SSEs and REs remain poorly understood, adding more mysteries to the initiation of earthquakes. Here, we perform systematic numerical simulations to explore the relationships between SSEs and REs on faults including locally increased fluid pressure. We identify four types of fault slip behaviors distinguished by SSE and earthquake initiation mode. The observed interactions between SSEs and REs share similar features with those reported for natural earthquakes. Our results show that the occurrence of SSEs may temporarily hasten fault decoupling, leading to the clock advance of mainshocks. Furthermore, the interactions between SSEs and REs are more complicated than previously thought. On the one hand, since SSEs with extremely high peak slip rates tend to directly transform into huge earthquakes, the possibility of huge earthquakes may increase when SSEs happen. On the other hand, there is no threshold in peak slip rate for SSEs to trigger the nucleation of REs. Therefore, it is difficult to distinguish the SSEs that could trigger a huge earthquake from regular ones only with the knowledge of the peak slip rate. We also verify that the spatial extent of SSEs is related to the occurrence of earthquakes to some extent. These findings may have major implications for understanding the interactions between SSEs and REs, and the mechanism of earthquake initiation.

40Ar–39Ar geochronology and palaeostress analysis using lamprophyre dikes and quartz veins in the Sizhuang gold deposit: new implications for Early Cretaceous stress regime in the Jiaodong Peninsula, North China Craton

AbstractLamprophyre dikes and quartz veins in the Sizhuang gold deposit are used to date and unravel the Early Cretaceous stress regime in the Jiaodong Peninsula, North China Craton. The lamprophyre dikes are grouped into two major sets, trending NNW–SSE and NNE–SSW, respectively, and a subsidiary one, trending WNW–ESE, whereas the quartz veins trend mainly NNE–SSW. The age of lamprophyre dikes’ intrusion was robustly calculated at c. 119 Ma by phlogopite 40Ar–39Ar dating. The fuzzy clustering technique defined four stress states, which were grouped into three stress regimes in Sizhuang. Furthermore, these stress regimes were interrelated with two regional far-field stress regimes, ST1 and ST2, defined by the available published fault-slip data near Sizhuang by applying the separation and stress inversion TR method (TRM). The palaeostress reconstruction indicates that extension and strike-slip tectonics (i.e. transtension) affect the emplacement of the lamprophyre dikes and quartz veins. More precisely, the dike emplacement occurred under unstable stress conditions related to the shift from E–W pure extension–transtension to WNW–ESE transtension, whereas the quartz veins formed under relatively stable WNW–ESE transtension with the variant and increasing fluid pressure ( ${P_{\rm{f}}})$ giving rise to the strike-slip against dip-slip kinematics along the faults. The change from the ST1 to ST2 stress regimes reflects the significant clockwise rotation in the palaeo-Pacific plate subduction direction and defines the switching time at c. 119 Ma as precisely obtained by the lamprophyre dating.

Probabilistic Evaluation of Susceptibility to Fluid Injection-Induced Seismicity Based on Statistics of Fracture Criticality

AbstractFault reactivation and associated microseismicity pose a potential threat to industrial processes involving fluid injection into the subsurface. In this research, fracture criticality, defined as the gradient of critical fluid pressure change to trigger seismicity (Δpc/h), is proposed as a novel reservoir depth-independent metric of fault slip susceptibility. Based on statistics of the fracture criticality, a probabilistic evaluation framework for susceptibility to injection-induced seismicity was developed by integrating seismic observations and hydrogeological modelling of fluid injection operations for faulted reservoirs. The proposed seismic susceptibility evaluation method considers the injection-driven fluid pressure increase, the variability of fracture criticality, and regional fracture density. Utilising this methodology, the probabilistic distribution of fracture criticality was obtained to evaluate the potential for injection-induced seismicity in both fault and off-fault zones at the Hellisheiði geothermal site, Iceland. It has been found that the fracture criticality within both fault and off-fault zones shows natural variability (mostly ranging between 0.001 and 2.0 bar/km), and that fault zones tend to be characterised by larger fracture criticality values than the off-faut zones. Fracture criticality values estimated within each zone roughly follow a Gaussian distribution. Fault zones around five geothermal fluid re-injection wells at the site were estimated to have relatively high probability of seismic event occurrence, and these regions experienced high levels of induced seismicity over the microseismic monitoring period. The seismotectonic state estimated for each zone is generally consistent with the forecasted susceptibility to seismicity based on statistics of fracture criticality.

Influence of high pressure pulsating excitation on pipe joint sealing based on multiscale contact analyses

Most of the leakage faults in hydraulic pipeline systems occur in the pipe joint. The research on the high-pressure sealing and reliability of the pipe joint is very important in the application of civil aircraft parts. On the basis of studying the characteristics of pressure pulsating fluid, this paper explores the influence of a high pressure pulsating fluid on the sealing performance of flameless extruded pipe joints and analyzes the influence of the internal fluid pulsating amplitude and fluid under different pressures on the contact stress distribution of the sealing surface of the pipe joint. The results show that with the increase in flow pulsation amplitude from 0.5% to 5%, the amplitude of contact stress on the sealing surface decreases with creep time, which makes the sealing performance better. However, the effective working time of the joint as a whole decreases from 2000 to 194 h. The high-stress area of the contact surface expands as the fluid pressure increases, and the high internal fluid pressure obviously improves the sealing effectiveness and reliability of the pipe joint. In addition, the influence of fluid pulsation amplitude on the leakage rate of the joint is much greater than that of the fluid pressure.

Experimental modelling of primary migration in a layered, brittle analogue system

A 2D Hele-Shaw cell was built to study microfracture nucleation, growth, and network formation during internal fluid production. Fluid is slowly produced into a low permeability solid, which leads to a local fluid pressure increase that controls the nucleation of microfractures that grow and then connect to create flow pathways. This process occurs during the primary migration of hydrocarbons in source rocks, which is the main topic of our study. It may also occur in other geological systems, such as the expulsion of water during dehydration of clay-rich sediments in sedimentary basins or serpentinite rocks in subduction zones and the transport of magmatic melts. Our system consists of a transparent, brittle gelatin material mixed with yeast and sugar. The consumption of sugar by yeast leads to CO2 formation, resulting in microfracture nucleation and growth. We varied three parameters, (1) anisotropy (i.e., number of layers), (2) lateral sealing, and (3) rate of fluid production. We tracked fluid movement through the opening and closing of microfractures within the system. Microfracture nucleation density is similar in a layered system to previous studies (0.45 microfracture per cm2). However, we observed that lateral confinement (0.31 microfracture per cm2) and rate of expulsion (0.99 microfracture per cm2) affect nucleation density and the geometrical characteristics of the microfracture network. The size, extent, and geometry of the microfracture network are dependent on all three parameters investigated, where lateral confinement and a higher rate of expulsion result in greater microfracture network connectivity. Layers control the angle of intersection between microfractures. Furthermore, layering and sealing have an impact on fracture topology. Results also show that the microfracture pattern significantly influences the fluid expulsion rate. Our results have direct applications to understanding how fluid migration occurs in low-permeability rocks through the development of a connected microfracture network produced by internal fluid generation.

The ambivalent nature of the relationship between lymphatics and cancer

Do lymphatic vessels support cancer cells? Or are they vessels that help suppress cancer development? It is known that the lymphatic system is a vehicle for tumor metastasis and that the lymphangiogenic regulator VEGF-C supports the tumor. One such role of VEGF-C is the suppression of the immune response to cancer. The lymphatic system has also been correlated with an increase in interstitial fluid pressure of the tumor microenvironment. On the other hand, lymphatic vessels facilitate immune surveillance to mount an immune response against tumors with the support of VEGF-C. Furthermore, the activation of lymphatic fluid drainage may prove to filter and decrease tumor interstitial fluid pressure. In this review, we provide an overview of the dynamic between lymphatics, cancer, and tumor fluid pressure to suggest that lymphatic vessels may be used as an antitumor therapy due to their capabilities of immune surveillance and fluid pressure drainage. The application of this potential may help to prevent tumor proliferation or increase the efficacy of drugs that target cancer.

Intrafasciomembranal Fluid Pressure: A Novel Approach to the Etiology of Myalgias.

Fascia is a continuous membrane (fasciomembrane) that enables differentiation of fluid pressure on either side. Fascia membrane also enables an internal increased fluid pressure at all muscle levels (fibers, fiber bundles, skeletal muscles, compartments), and the author introduces a new unifying term for these pressures, regardless of the anatomical level - the intrafasciomembranal fluid pressure (IFMFP). Swelling, pain, and loss of tissue function are identified as common cardinal symptoms in trigger point (TrP), chronic exertional compartment syndrome (CECS), overtraining syndrome (OTS), and delayed onset muscle soreness (DOMS). Existing literature and an overall assessment indicate that intramuscular conditions related to fluid flow and pressure play a central role in different conditions, providing a common biomechanical explanation of the etiology and influence, supporting the article's theory that an increased IFMFP plays a key role in these conditions.

Failure modes in fluid saturated rocks: deformation processes and mode-switching

AbstractWe consider the implications of adding a cap to the yield surface for elastic–plastic and elastic–visco-plastic solids with coupling between deformation, fluid flow and mineral reactions. For a suitable combination of (low) permeability and strain rate, opening-mode veins can form in compression. Such behaviour is enhanced by dissolution and by simultaneous mineral reactions with negative ΔV. These are the opening-mode equivalents of compaction bands in rocks with high permeability. Stylolite parallel veins are considered as forming in this way; such veins are commonly the laminated or ribbon-quartz veins associated with intense gold mineralization. Axial plane veins and melt segregations are in this class also. The addition of a yield surface cap limits the permissible stress states portrayed by a failure-mode diagram and has implications for breccia formation. Failure discontinuities that form at the cap require adecreasein fluid pressure to form as opposed to extension joints and veins that require anincreasein fluid pressure; discontinuities that form at the cap are in orientations that are commonly interpreted as reactivated early discontinuities. The switching between high fluid pressure and low fluid pressure, which we callmode-switching, arises from competition between mineral dissolution and deposition. This is an alternative to the fault-valve mechanism and does not require fault reactivation or failure at a ‘seal’ linked to seismicity or fault reactivation. The capped yield surface concept provides a unifying self-consistent approach for vein/breccia formation and for the kinematics of brittle and visco-plastic rocks.

Effects of confining pressure and microscale heterogeneity on hydrocarbon retention and pore evolution from artificial maturation of Eagle Ford Shale

Although shale heterogeneity has recently emerged as a key topic in unconventional petroleum systems, hydrocarbon (HC) retention and pore evolution in organic-rich shales still remain poorly constrained. In this study, an organic-rich Eagle Ford Shale sample (EqVRo = 0.92%) from a shale-oil prospecting well in South Texas was selected for gold-tube pyrolysis experiments to investigate organic matter (OM) -hosted pore development versus confining pressure during thermal maturation. Before heating, the OM-type heterogeneity and associated pore characteristics in the sample were examined by thin section and scanning electron microscopy imaging, combined with elemental mapping by X-ray energy-dispersive spectroscopy. Four forms of OM occurrence that are closely associated with different mineral matrix domains are distinguished, including the ductile oil-bearing primary OM and rigid primary OM in the siliceous-argillaceous seams, as well as the secondary OM in coccolith-rich lenses and in foraminifera chambers. From heating experiments, the pressure effect on pore evolution was found to be pronounced for the secondary OM in the foraminifera chambers, in which the coalescence of small pores to larger pores upon OM maturation was accelerated by increasing fluid pressure, accompanied by arrangement and densification of OM structures. However, the expulsion effect as a function of confining pressure seems to be evident only for the secondary OM in the coccolith-rich lenses. In contrast, the two types of primary OM in the siliceous-argillaceous seams do not show any apparent changes in pore development over the investigated pressure range of 10 to 120 MPa, probably due to stiffer mechanical properties of primary OM as compared to secondary OM. The discrepancies in pore evolution of different OM types as a response to the variation in confining pressure upon maturation primarily depend on the physical-chemical properties of these various OM materials.Of further importance, observed differences in OM evolution and associated pore characteristics in response to the variation in confining pressure imply that the microscale heterogeneity of shale fabric controls the extent of oil retention and pore evolution. In contrast to the intragranular pores in the foraminifera chambers, the intergranular pores in the coccolith-rich lenses from the Eagle Ford Shale sample are relatively smaller, yet more likely interconnected. Thus, these coccolith-associated pores may provide not only significant storage space but also a major flow pathway for HC production. Our investigation at the microscopic scale provides concepts indicating that HC retention and OM-hosted pore evolution occur differently in two contrasting types of mineral matrix pores, which is critical to successful unconventional shale oil and gas exploration in sedimentary basins.