High Fluid Pressure Research Articles

Abstract 4009: Discovery of PLM-102, a highly potent 3rd generation FLT3 inhibitor, in drug-resistant FLT3-ITD-TKD mutated acute myeloid leukemia

Abstract Mutations of the FMS-like tyrosine kinase 3 (FLT3) gene occur in approximately 25 ~ 30% of all acute myeloid leukemia (AML) cases and FLT3-ITD mutations are associated with a particularly unfavorable prognosis, with an increased risk of relapse and shorter overall survival (OS) compared with AML patients without the mutation. Even though multiple FLT3 inhibitors are in various stages of clinical evaluation, resistance to FLT3 inhibitors resulting from acquired point mutations in tyrosine kinase domain (TKD) have limited the sustained efficacy of treatments. Among them, a “gatekeeper” mutation (F691L) is resistant to most available FLT3 inhibitors. Here, we show the efficacy and mechanism of PLM-102, developed an orally available and highly selective small molecule, in overcoming drug-resistant FLT3-ITD-TKD mutations as a strong candidate of the 3rd generation of FLT3 inhibitor. PLM-102 displays extraordinary potency of enzyme inhibitory activities of all FLT3 WT/mutants including F691L with IC50 values of <1 nM. In FLT3-ITD-positive cell lines (MV4-11, MOLM-13, MOLM-14, Ba/F3-ITD-D835Y, Ba/F3-ITD-F691L), PLM-102 shows about 18~25-fold higher anti-proliferative activities than Gilteritinib. Also, PLM-102 potently inhibited the phosphorylation of FLT3 and its downstream signaling pathways, and induced apoptosis as evidenced by PARP-cleavage and caspase-3 activation. Moreover, in AML-related xenograft mouse models (MV4-11, MOLM-14, Ba/F3-ITD-D835Y, Ba/F3-ITD-F691L), once-daily oral dose of PLM-102 significantly suppressed the tumor growth and achieved complete tumor regression. In addition, the outstanding efficacy of our compound has been confirmed in large tumor xenograft models. These results are very encouraging because large tumors have a limited blood supply and high interstitial fluid pressure, leading to a poor absorption of anticancer drugs. Pharmacokinetics of PLM-102 displayed higher bone-marrow exposure indicating better target engagement and benefits in the clinical translation in AML. In conclusion, PLM-102 is a promising therapeutic candidate for the FLT3-ITD-mutated AML as well as the acquired resistance to current FLT3 inhibitors. Citation Format: Jin-Hee Park, Jae-Seon Lee, Su-jin Oh, So-Deok Lee, Yong June Choi, Keon Wook Kang, Miran Moon, Soo Yeon Jang, Myung Jin Kim, Yong-Chul Kim. Discovery of PLM-102, a highly potent 3rd generation FLT3 inhibitor, in drug-resistant FLT3-ITD-TKD mutated acute myeloid leukemia. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4009.

Synthesis and Plugging Performance of Nano-Micron Polymeric Gel Microsphere Plugging Agents for Oil-Based Drilling Fluids

As shale gas recovery progresses to deep layers, the wellbore instability during drilling in applications of oil-based drilling fluids (OBFs) becomes increasingly severe. This research developed a plugging agent of nano-micron polymeric microspheres based on inverse emulsion polymerization. Through the single-factor analysis with respect to the permeability plugging apparatus (PPA) fluid loss of drilling fluids, the optimal synthesis conditions of polymeric microspheres (AMN) were determined. Specifically, the optimal synthesis conditions are as follows: the monomer ratio of 2-acrylamido-2-methylpropanesulfonic acid (AMPS): Acrylamide (AM): N-vinylpyrrolidone (NVP) were 2:3:5; the total monomer concentration was 30%; the concentrations and HLB values of emulsifier (Span 80: Tween 60) were 10% and 5.1, respectively; the oil-water ratio of the reaction system was 1:1; the cross-linker concentration was 0.4%. The polymeric microsphere (AMN) produced via the optimal synthesis formula had the corresponding functional groups and good thermal stability. The size distribution of AMN ranged mainly from 0.5 to 10 μm. The introduction of AMND in OBFs can increase the viscosity and yield point of oil-based drilling fluids and slightly decrease the demulsification voltage but significantly reduce high temperature and high pressure (HTHP) fluid loss and permeability plugging apparatus (PPA) fluid loss. The OBFs with 3% polymeric microsphere dispersion (AMND) reduced the HTHP and PPA fluid loss by 42% and 50% at 130 °C, respectively. In addition, The AMND maintained good plugging performance at 180 °C. The AMN particles can block leakoff channels of artificial cores, effectively prevent the invasion of oil-based drilling fluids into formations and suppress pressure transfer. OBFs with 3% AMND enabled the corresponding equilibrium pressure to decrease by 69%, compared with that of the OBFs. The polymeric microspheres had a wide particle size distribution. Thus, they can well match leakage channels at various scales and form plugging layers via compression-deformation and packed accumulation, so as to prevent oil-based drilling fluid from invading formations and improve wellbore stability.

Shallow Low‐Velocity Layer in the Hyuga‐Nada Accretionary Prism and Its Hydrological Implications: Insights From a Passive Seismic Array

AbstractShear wave velocity (Vs) estimations of accretionary prisms can pose unique constraints to the physical properties of rocks, which are hard to obtain from compressional velocities (Vp) alone. Thus, it would help better understand the fluid processes of the accretion system. This study investigates the Vs structure of the Hyuga‐nada accretionary prism using an array of ocean‐bottom seismometers (OBSs) with a 2 km radius. Teleseismic Green's functions and a surface wave dispersion curve are inverted to one‐dimensional Vs structures using transdimensional inversion. The results indicate the presence of a low‐velocity zone 3–4 km below the seafloor. The reduced Vs corresponds to a reduced Vp feature obtained in a previous seismic refraction survey, and the high Vp/Vs ratio suggests the presence of high pore fluid pressure. In addition, the resolved lithological boundary exhibits a sharp offset that extends laterally across the OBS array. We attribute this offset to a blind fault below while acknowledging other possibilities, such as due to mud diapirism or intense fracturing. The predicted fault is located at the Kyushu–Palau Ridge flank, oriented roughly parallel to the ridge axis, and thus likely caused by ridge subduction. This fault may act as a fluid conduit, contributing to the formation of a fluid reservoir beneath the compacted sediment layers.

Shattered Veins Elucidate Brittle Creep Processes in the Deep Slow Slip and Tremor Region

AbstractDeep Slow Slip and Tremors (SSTs) are a combination of transient clusters of tectonic tremors and slow slip associated with extremely elevated fluid pressures. SSTs are thought to reflect a transition from viscous to brittle plate interface rheology and likely exert a first‐order control on megathrust seismicity. Nevertheless, the deformation mechanisms governing the source of SSTs remain elusive. We herein document the occurrence of vein networks precipitated and brecciated within the deep SST region under blueschist‐facies conditions. These lawsonite‐rich vein sets exhibit extensive evidence of brittle deformation and are spatially related to localized, finely milled (cataclastic) shear bands. Petro‐geochemical data reveal that brittle deformation was accompanied by the injection of several ultramafic‐, mafic‐ and metasedimentary‐derived fluid pulses, imprinting characteristic Cr, high field strength elements, and light over heavy rare earth elements positive anomalies in the vein breccias while leaching light rare earth elements from the cataclastic blueschist host. Our results suggest that metamorphic veins represent zones of mechanical anisotropy within the rock volume prone to localized shearing, brittle deformation and episodic injection of externally derived fluids. These networks demonstrate the importance of former vein sets as structural heterogeneities in triggering fluid‐controlled brittle creep events. The combined effects of high pore fluid pressures and rheological heterogeneities in the form of metamorphic veins could trigger the nucleation and propagation of SSTs at the margins of this mechanically anisotropic environment, and thus determine where slip will take place along deep subduction interfaces.

Novel stirring-rod-inspired mixer-integrated printhead for fabricating gradient tissue structures

Conventional methods for creating gradient tissue structures using extrusion-based 3D printing (E3DP) systems involve using mixers to create homogeneous materials. However, commercially available mixers can generate high fluid pressure and shear force that harm cells. Hence, a new mixer-integrated printhead was developed, inspired by stirring-rod-assisted mixing processes. The as-designed mixing system was validated through computational fluid dynamics (CFD) simulations using input parameters including ink viscosity, density, and velocity vector and output parameters including material volume fraction, average fluid pressure, and shear force. Six-stir element mixer units were used to comprehensively analyze material mixing while considering the fluid volume fraction after flowing through the mixers. Printheads integrated with multiple discrete mixers with consistent spiral directions, performing well when introducing gaps, were used to reduce the cell pressure and shear force. The optimal mixer design, with two 1.62-mm gaps and six-stir element mixer units sharing the same spiral structure, reduced the average fluid pressure and shear force by 3.196e+4 Pa and 0.368e+2 Pa, respectively, compared with a commercial static mixer. Finally, a mixer-integrated printhead was manufactured, matching well with the original design. This research could improve E3DP systems and serve as a design reference for 3D printing structures of varying stiffness.

Achieving robust and enhanced pool boiling heat transfer using micro–nano multiscale structures

Vapor chamber thermal management technology has become a high-reliability cooling method to solve the heat dissipation problem. However, this is still a crucial challenge to overcome when the capillary wick is exposed to harsh service environments. In this paper, a fabrication method of capillary wicks with micro–nano multiscale structures combining micro hot embossing and high-pressure hydrothermal treatment is proposed. Micro pyramid-channel is fabricated by micro hot embossing, and when the axis-to-diameter ratio of nanobars reaches 3.16–3.17, superhydrophilicity is realized. In the pool boiling experiment, the heat transfer performance of the pyramid-channel is better than that of the triangular-channel. Importantly, the superhydrophilic micro–nano structures achieve significantly improved critical heat flux and heat transfer coefficient simultaneously, increased by 162.1% and 180.8%. Moreover, the fabricated micro–nano capillary wick, which comprise high-strength pyramid-channel and specific wettability nanostructures, can maintain their outstanding superhydrophilicity and superhydrophobicity and their enhanced boiling property even after high-pressure high-velocity fluid scouring. The proposed cost-effective fabrication method provides an ideal and industrialized approach for the mass production of vapor chamber capillary wicks suitable for severe application environments.

Measurements of Wave‐Induced Attenuation in Saturated Metapelite and the Band‐Limitation of Low‐Frequency Earthquakes

AbstractThe most common explanation for the depletion of high frequency waves that defines low‐frequency earthquakes (LFEs) and very low‐frequency earthquakes (VLFEs) is that fault rupture and slip are slower than typical earthquakes. However, it is difficult to rule out the possibility that the high frequency waves are produced during slip, but attenuated near the LFE source. One reason this hypothesis has been poorly tested is that there are no measurements of attenuation on the relevant rocks. We present the results of forced oscillation experiments that measure the frequency‐dependent attenuation of a chlorite‐rich metapelitic schist, a lithology found along the subduction plate boundary where LFEs and VLFEs have been documented. Experiments were run on dry and water‐saturated schist at effective pressures of 2–10 MPa and at frequencies of 2 × 10−5–30 Hz. We find that pore fluids and low effective pressure result in the attenuation of high frequencies. The frequency‐dependent attenuation is consistent with the concomitant operation of two wave‐induced fluid flow mechanisms, squirt flow, and patchy saturation. When the effects of these mechanisms are extrapolated to geologic conditions using rock physics models, our results predict that attenuation is capable of completely diminishing the frequencies depleted in LFEs and VLFEs. Therefore, LFEs and VLFEs may not necessarily record slow fault slip, but possibly the presence of high fluid pressure.

Epidemiology, management and outcomes of Cryptococcus gattii infections: A 22-year cohort.

Cryptococcus gattii is a globally endemic pathogen causing disease in apparently immune-competent hosts. We describe a 22-year cohort study from Australia's Northern Territory to evaluate trends in epidemiology and management, and outcome predictors. A retrospective cohort study of all C. gattii infections at the northern Australian referral hospital 1996-2018 was conducted. Cases were defined as confirmed (culture-positive) or probable. Demographic, clinical and outcome data were extracted from medical records. 45 individuals with C. gattii infection were included: 44 Aboriginal Australians; 35 with confirmed infection; none HIV positive out of 38 tested. Multifocal disease (pulmonary and central nervous system) occurred in 20/45 (44%). Nine people (20%) died within 12 months of diagnosis, five attributed directly to C. gattii. Significant residual disability was evident in 4/36 (11%) survivors. Predictors of mortality included: treatment before the year 2002 (4/11 versus 1/34); interruption to induction therapy (2/8 versus 3/37) and end-stage kidney disease (2/5 versus 3/40). Prolonged antifungal therapy was the standard approach in this cohort, with median treatment duration being 425 days (IQR 166-715). Ten individuals had adjunctive lung resection surgery for large pulmonary cryptococcomas (median diameter 6cm [range 2.2-10cm], versus 2.8cm [1.2-9cm] in those managed non-operatively). One died post-operatively, and 7 had thoracic surgical complications, but ultimately 9/10 (90%) treated surgically were cured compared with 10/15 (67%) who did not have lung surgery. Four patients were diagnosed with immune reconstitution inflammatory syndrome which was associated with age <40 years, brain cryptococcomas, high cerebrospinal fluid pressure, and serum cryptococcal antigen titre >1:512. C. gattii infection remains a challenging condition but treatment outcomes have significantly improved over 2 decades, with eradication of infection the norm. Adjunctive surgery for the management of bulky pulmonary C. gattii infection appears to increase the likelihood of durable cure and likely reduces the required duration of antifungal therapy.

Low-frequency unsteadiness of recompression shock structures in the diffuser of supersonic ejectors

Supersonic ejectors are passive gasdynamic devices that compress a low-pressure fluid by utilizing the kinetic energy of a high-pressure fluid in a variable area duct. The ejector consists of a primary supersonic nozzle in a mixing duct where the secondary flow is entrained and mixed. The mixed flow can undergo a series of recompression shocks resulting in a subsonic flow in the diverging portion to aid pressure recovery. Recompression shocks usually lead to unsteady shock boundary layer interactions. The performance of the ejector is influenced by shear layers, shock and expansion waves, and their mutual interactions. While existing literature has extensively dealt with mixing of the primary and secondary flows, the unsteadiness in flow resulting from recompression shocks has been seldom investigated. Fluctuations in pressure due to the unsteadiness of the shock often lead structural fatigue issues. This paper reports a detailed investigation on low-frequency unsteadiness of recompression shock using high-speed schlieren images and dynamic pressure measurements. Modal analyses using proper orthogonal decomposition and dynamic mode decomposition techniques are used to determine the dominant spatial modes and associated frequencies. Multimodal frequencies ranging between 80 and 300 Hz are observed. These findings are further corroborated by Fourier and wavelet transformations of the experimentally measured wall static pressure signals. Subsequently, scaling parameter is established for the dominant frequencies based on flow velocities upstream of the shock and the distance between two consecutive shocks. This results in a unique scaling frequency of 4.58% ± 18%, for the recompression shock independent of operating conditions.

Simulations of high-pressure fluid flow in a pre-cracked rock specimen composed of densely packed bonded spheres using a 3D CFD model and simplified 2D coupled CFD-DEM approach

Simulations of high-pressure fluid flow in a pre-cracked rock specimen composed of densely packed bonded spheres using a 3D CFD model and simplified 2D coupled CFD-DEM approach

Effect of Qusaiba shale formation on high-pressure high-temperature drilling fluids properties

Drilling operations encounter various problems, many of which affect mud quality and may delay or suspend drilling. Wellbore instability is one of the many problems that drilling engineers face while using water-based drilling fluids (WBDF). When WBDFs contact active clay minerals, they may hydrate and swell, damaging the wellbore. In this study, the effects of Saudi Qusaiba shale kaolin clay on WBDF characteristics were examined. Kaolin clay was used as drilled formation cutting at different concentrations (5, 10, 20, and 30 lb/bbl). A detailed study examined how kaolin clay affects mud. Drilling fluid density, alkalinity, rheological, viscoelasticity, filtration behavior, and particle settling were examined before and after adding kaolin clay particles. Experimentally, the higher temperature of the practical environment was simulated by bringing the temperature up to 250 °F. The results showed that there are two clusters of kaolin clay below and above 10 lb/bbl. Kaolin clay concentrations over 10 lb/bbl had a negative effect on fluid characteristics, whereas lower amounts had very little effect. The apparent viscosity (AV) increased by 3% and 16% at 5 and 10 lb/bbl, but it jumped to 72% and 89% after 20 and 30 lb/bbl of kaolin clay. At 20 and 30 lb/bbl of kaolin clay, the yield point (YP) increased by 213% and 377%, respectively. Time sweep indicated continual gel strength increase. The addition of kaolin clay reduced the alkalinity of the WBDF which allowed the clay minerals to swell. Furthermore, the filter cake thickness and filtration volume showed a gradual increment as the concertation of the kaolin clay increased due to the accumulation of the clay solid in the filter cake layer.

Antithrombotic and Flow Drag‐Reducing Material for Blood‐Contacting Medical Devices

AbstractBlood‐contacting medical devices are often associated with shear‐induced and contact activation thrombosis. Superhydrophobic materials have shown promise to reduce flow drag forces, but not contact activation. Here, a strategy of selectively grafting a potent anti‐thrombin compound on the tips of the surface microstructures of a superhydrophobic polytetrafluoroethylene foam, is presented, to concurrently achieve drag reduction and anti‐thrombosis. This work shows that two grafting approaches – Argon plasma or piranha solution treatment – followed by covalent cross‐linking can successfully graft the drug to the outer tips of the foam and provide anti‐thrombotic functionality. By avoiding grafting to the inner regions of the foam, the surface's drag reduction properties can be retained. The functional durability of the grafted surfaces is evaluated by strong water jetting, which demonstrates that the plasma approach can withstand substantial fluid shearing but not the piranha approach, although the plasma approach involves stronger compromise to the drag reduction capabilities. As the proposed selective grafting strategy is applied to a bulk foam, it can be complemented with a previously proposed strategy of supplying air pressure to the foam pores to bolster resistance to fluid impalement and plastron dissolution, allowing the material to be used in medical devices with high fluid pressures.

Preliminary Test of Gas Wave Ejector in Coalbed Methane Well Site and Impact Analysis of Fluid Medium Characteristics on Its Pressure Port Design

Gas wave ejector (GWE) is an efficient energy conversion device which can recover and utilize excess pressure energy of high pressure fluid. It has significant application value in the sustainable development of energy resources, including the exploitation and transportation of natural gas. The first practical application test of GWE in the natural gas industry is completed in this study. The mechanisms and regulations of the effect of actual gas properties on the pressure port design of GWE were also investigated. The primary conclusions are as follows: the composition of working medium significantly affects the propagation velocity of pressure waves. The wave propagation velocity increases as methane purity (φCH4) rises. The equipment efficiency was decreased by up to 23% of the optimal value as a result of the variation in port position brought on by the increase in φCH4 from 0.7 to 1.0. The variation of working pressure ratio has a greater impact on the device performance than the pressure value when the pressure port design kept unchanged. The intake temperature fluctuation in the range of -30°C to 50°C has no obvious influence on the ideal port design. In the coal-bed methane well site industrial test, GWE accomplishes a recovery of low-pressure well by roughly 8.83 × 10 3 N m 3 / d , demonstrating its excellent ejection capacity. In addition, the variable speed test conducted under different working conditions shows that the equipment performance can be effectively enhanced by adjusting the rotation speed as the equipment structure remains unchanged with the changing working pressure/pressure ratio. In the field test range of this study, the increase of equipment ejection rate obtained by speed adjustment can rise up to 12% of the corresponding value at the designed rotation speed.

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.

Thermo-economic optimization of a novel confined thermal energy storage system based on granular material

Concentrated solar power is a suitable technology for production of green electricity. However, to attain a uniform electricity production, concentrated solar power should be coupled with large Thermal Energy Storage (TES) systems. Among the different technologies of TES systems, storage of sensible heat in granular material is widely used due to its simple operation. These TES systems store energy as an increase of temperature of a large mass of small solid particles, through which a fluid circulates exchanging heat. TES systems are typically operated in a fixed bed regime, maximizing their exergy output, thus limiting the maximum allowable velocity of the fluid flow. In this work, a novel confined bed is proposed to mechanically prevent the motion of the solid particles conforming the TES system even for high fluid velocities, to guarantee that the exhaust temperature of the fluid is maximum during a discharge process. In this novel confined bed, a thermocline evolves from bottom to top of the system, separating the low and high temperature of the bed during the discharge process. An analytical model was applied to describe the evolution of the thermocline and the effect of the different operating parameters on the thermocline thickness.The effect of the thermocline thickness was combined with a thermo-economic analysis of a confined bed TES system proposed for a case of study. The new confined bed here proposed was optimized considering thermodynamics aspects, namely the fluid exergy increment in the bed, and economic factors, specifically the total investment cost of the TES system. The optimization resulted in low values of the fluid velocity, between 0.2 and 0.4 m/s, but still higher than the minimum fluidization velocity of sand particles of 750 μm, justifying the requirement of a confined bed, and low bed aspect ratios, between 0.25 and 0.9, to prevent excessively high fluid pressure drops. However, the bed aspect ratio increases significantly for higher granular material particle sizes, up to a ratio of bed height to diameter of 3 for a particle size of 10 mm and a TES demand time of 6 h.

Free water input into the New Britain subduction zone in Solomon Sea estimated from reflected seismic data

AbstractIt is of great significance to examine the distribution of the fluid within the subduction zone to estimate the water flux into the subduction zone and to study the motion state of the subducting plate. The interaction of the Western Pacific Plate and the Indo‐Australian Plate controls the subduction and expansion of the Solomon Basin where the mechanisms governing plate activity remain unclear but are typically associated with high pore fluid pressures and stabilizing frictional conditions. Combining the long streamer seismic data (200) and nine well logs inside the work area, we used constrained sparse spike inversion to obtain the P‐wave impedance profile. Then we constructed reservoir rock physics models to predict the fluids distribution in New Britain Trench subduction system in Solomon Sea. The genetic algorithm was used to guide the inversion of the pore fluid distribution. The water content profile revealed the shallow structure of the New Britain Trench subduction system in Solomon Sea, including the water content within the basalt layers. We determined that in certain cases, faults identified from the reflection data were associated with low‐impedance anomalies, and this may indicate that they are zones of high porosity that act as conduits for fluid flow. The continuity of the distribution of water content under the New Britain Trench suggests that there is a large amount of free water that subducts deeply and may be important in controlling the motion state of the subducting plate. We assume that the water saturation is 1. Therefore, the free water flux entering the deep circle with the subducting plate is estimated to be 158 Tg/Ma/m totally, including 53.724 Tg/Ma/m in the sediment and 105.06 Tg/Ma/m in the basalt. This study provides insight into the structure of free water in the New Britain subduction zone and reveals the potential for the direct estimation of the 2D structural distribution of water content using geophysical survey data.

Pore pressure evolution in bed sediment overridden by debris flow: A general formulation

AbstractDebris flows can grow dramatically in volume and mobility as they override bed sediment due to the reduction in bed friction resistance caused by high pore fluid pressure (PP). However, the mechanisms that control PP evolution in overridden bed sediment are still unclear. Here, a new mathematical model clarifies how diverse styles and magnitudes of PP evolution can result from regulation of the flow diffusion and shear contraction of bed sediment. Normalization of the model equations shows that the propensity for PP generation depends on timescales of PP diffusion and deformation of the bed grains. The PP of saturated bed sediment under immobile conditions is equal to the fluid pressure at the bottom of the flow due to a non‐flux basal boundary. However, the PP of unsaturated bed sediment is lower than that of the overlying flow. PP diffusion from a debris flow into an unsaturated bed increases with the bed’s permeability and water content. The shear deformation behavior changes from undrained to drained with increasing permeability or decreasing shear velocity of the saturated bed sediment, leading to a reduced magnitude of pore pressure. By contrast, the shear deformation transitions from drained to undrained behavior with increasing permeability and water content of unsaturated bed sediment. The entrainment rate and erosion pattern of bed sediment are closely related to the PP evolution and liquefaction ratio of the bed sediment due to Coulomb‐friction shear tractions. Our models can be used to interpret the feedback of PP on the flow momentum during debris flow entrainment.

Structure Size Optimization and Internal Flow Field Analysis of a New Jet Pump Based on the Taguchi Method and Numerical Simulation

Interlayer contradiction (high-pressure oil that prevents low-pressure oil from being extracted) has always been the main factor affecting the oil-recovery efficiency of the many oil-bearing series in shale oil wells in Eastern Shandong, China. If steps to deal with interlayer contradiction are not taken, Shengli Oilfield’s oil-recovery efficiency will be significantly reduced after a certain period of exploitation. Furthermore, as the drilling depth increases, the formation-fluid supply capacity of Shengli Oilfield becomes worse and further increases the difficulty of oil recovery as well as production costs. In order to improve the oil-recovery efficiency of shale oil wells in Eastern Shandong and realize cost reductions and efficiency increases, we designed a new jet pump in this study. The pump can be used for oil recovery according to the principle of Venturi jet propulsion, as the required power fluid is not a high-pressure fluid injected from the ground, but rather high-pressure oil that is present in the formation. Through the analysis of the overall structure of the new jet pump, it was found that the pump could not only transform the existing interlayer contradiction (co-mining of high and low oil layers by utilizing interlayer contradiction), but also had the characteristics of a simple structure and low production costs. Since the structural dimensions of the jet pump and the physical characteristic parameters of the fluid have significant impacts on pump efficiency, we first analyzed the internal flow field of the jet pump by using numerical simulations and found that the throat–nozzle distance, area ratio, throat length–diameter ratio, diffuser angle, and flow ratio had the most significant impacts on pump efficiency. After obtaining the specific numerical range of the abovementioned structural parameters when the pump efficiency was as its maximum, an orthogonal array designed according to the Taguchi method was used to conduct experiments. According to a range analysis and an analysis of variance, at an unchanged flow ratio (0.3156), the new jet pump achieved the highest efficiency (31.26%) when the throat–nozzle distance was 2.62 mm, the throat length was 46 mm, the throat diameter was 6.8 mm, and the diffuser angle was 7.5°. In comparing its efficiency with that before optimization, we noticed that the efficiency was significantly improved by about 10%. These research results not only offer a new idea for the existing oil-recovery mode, but also introduce a new method for optimizing the structure of jet pumps.

Advanced thermal fluid leakage detection system with machine learning algorithm for pipe-in-pipe structure

Pipe-in-pipe (PIP) system is essential for high thermal and high pressure fluid transportation. However, in the existing PIP systems, fluid leakage between inner and outer pipe has been difficult to discover or detect, which has worked as bottle neck to utilize PIP system in high risk industries as nuclear reactor, chemical plant or oil drilling systems. Here, we propose a noble PIP leakage detection system utilizing distributed temperature sensing (DTS) with Machine Learning (ML). With the Fourier transformed spectrogram data from DTS, the ML assisted system was able to detect 0.2∼7 ml/min liquid leakage between inner and outer pipe with the accuracy of 91.67% with a single embedded optical fiber. Under varying operating temperature, the system successfully distinguished leakage and non-leakage states using the optimized convolutional neural network. Our developed PIP leakage detection system can be deployed in safety-critical industrial systems for autonomous leakage detection.

The role of natural fracture activation in hydraulic fracturing for deep unconventional geo-energy reservoir stimulation

The presence of sealed or semi-sealed, multiscale natural fracture systems appears to be crucial for the successful stimulation of deep reservoirs. To explore the reaction of such systems to reservoir stimulation, a new numerical simulation approach for hydraulic stimulation has been developed, trying to establish a realistic model of the physics involved. Our new model successfully reproduces dynamic fracture activation, network generation, and overall reservoir permeability enhancement. Its outputs indicate that natural fractures facilitate stimulation far beyond the near-wellbore area, and can significantly improve the hydraulic conductivity of unconventional geo-energy reservoirs. According to our model, the fracture activation patterns are jointly determined by the occurrence of natural fractures and the in situ stress. High-density natural fractures, high-fluid pressure, and low effective stress environments promote the formation of complex fracture networks during stimulation. Multistage or multicluster fracturing treatments with an appropriate spacing also increase the stimulated reservoir area (SRA). The simulation scheme demonstrated in this work offers the possibility to elucidate the complex multiphysical couplings seen in the field through detailed site-specific modeling.