Injection Point Research Articles

Particle transport during asymmetric net-zero cyclic fluid flow: Flow in tubes and radial flow in fractures

Cyclic fluid flow enhances transport in porous media. We study particle transport during asymmetric net-zero cyclic fluid flow where the fluid injection rate is higher than the withdrawal rate. Inside a tube, the threshold fluid velocity required to mobilize a particle depends on the relative particle size: larger particles obstruct flow more effectively than small particles and require a smaller velocity to be transported. Then, flow rates can be selected so particles move forward during the injection phase and remain stationary during withdrawal. Similarly, asymmetric cyclic fluid flow transports particles radially along fractures despite the net-zero fluid flow. The flow velocity decreases away from the injection point and particles migrate to a characteristic “terminal radial distance”. Unlike tube flow, a grain has a diminishing obstructing effect on the radial flow field, and the threshold flow rate required to mobilize grains increases with increasing particle size during radial flow.

Dynamics of functional impairments during focal transient ischemia in three-dimensional cortical space

Ischemic injury in the cerebral cortex results in decreased electrical activity across all frequency bands and the emergence of abnormal electrophysiological patterns, including spreading depolarization (SD) and negative ultraslow potential (NUP) [1, 2]. Despite this, the specific dynamics of these changes in electrical activity within the three-dimensional cortical space during ischemia remain incompletely described and poorly understood. To simultaneously investigate changes in electrical activity across the layers of the cerebral cortex and in the horizontal cortical space, we used two linear 16-channel silicone probes (Neuronexus, USA) in combination with a flexible transparent 60-channel matrix of subdural electrodes (MIPT, Russia) and intrinsic optical signal imaging (IOS, 665 nm, transillumination mode) during focal ischemia induced by intracortical injection of the potent vasoconstrictor endothelin-1 (ET-1, 1 μL, 1 μM). These experiments were carried out in head-restrained rats under urethane anesthesia (1.5 g/kg). Formation of the ischemic lesion following ET-1 administration was correlated with clusters of SDs that demonstrated considerable variability in their propagation patterns within both vertical and horizontal planes. The initial SDs originated from the injection site of ET-1 and diffused across all cortical layers. Subsequently, the initiation point of the ensuing SDs gradually shifted towards the deeper layers while the electrical activity showed inadequate recovery between SDs within the injection site. SDs originating in the surrounding cortex did not invade the area near the injection point. Instead, they tended to spread around, often compartmentalizing in the superficial layers of the cortex. Some SDs were observed deep in the cortex, while others were detected on the surface via superficial electrodes and IOS, without leaving typical intracortical electrode traces. Electrographic activity was significantly depressed, especially in the superficial layers around the injection site, three hours after ET-1 administration. However, it returned to pre-ET-1 levels at the remote site, with a spatial gradient observed in subdural electrodes. Functional impairments corresponded to the histological lesion observed in coronal brain sections. Recently discovered NUPs were initiated by SD and were most prominent in the electrodes closest to the ET-1 injection site. These NUPs reached their maximal amplitude at one hour and subsided three hours after ET-1 injection. Our research indicates intricate dynamics in the creation of an ischemic focal point. The data gathered suggest that the emergence of cerebral harm during focal ischemia is associated with the growth of a focus extending both horizontally and vertically across cortical dimensions. This growth is fueled by the generation of SDs within the ischemic penumbra.

Preemptive deep parasternal intercostal plane block for perioperative analgesia in coronary artery bypass grafting with sternotomy: a randomized, observer-blind, controlled study

Objective The precise characteristics of deep parasternal intercostal plane block (DPIP), which is useful for providing analgesia during open heart surgery, have not yet been thoroughly elucidated. In this study, we aimed to establish the efficacy, define the cutaneous sensory block area, and determine the duration of preemptive DPIP block at the T3-4 or T4-5 intercostal spaces in patients undergoing coronary artery bypass grafting (CABG) via sternotomy. Design A prospective, single-blind, randomized controlled trial. Setting Patients were randomly divided into three cohorts, each containing thirty patients. Participants Ninety patients who underwent elective CABG via sternotomy were included in this study. Interventions The T3-4 and T4-5 groups received a preoperative single-shot DPIP block at the respective intercostal spaces. The principal objective of the study was to ascertain the optimal dosage of sufentanil administered during surgical procedures involving either a DPIP block or its absence, and to conduct a comparative analysis thereof across distinct injection sites, specifically T3-4 and T4-5. Secondary factors considered were the dosage of postoperative analgesics, the extent of sensory block on the skin, pain levels after extubation, time of recovery from anesthesia (time to extubation), duration of the block, and the occurrence of nausea and vomiting. Measurements & Main Results Preemptive DPIP block significantly reduced intraoperative sufentanil requirement compared to the control group (T3-4:0.38 ± 0.1, T4-5:0.32 ± 0.10, vs. Control:0.88 ± 0.3 μg/kg/h, p < 0.001). It also resulted in decreased analgesic consumption and numeric rating scale scores on the day of surgery (p < 0.01 compared to the control group). The DPIP block provided accurate anesthetic coverage of the dermatomes in the sternal region and reduced the time to extubation and postoperative nausea. However, the injection point (either via the T3-4 intercostal or the T4-5 intercostal) did not affect the efficacy. Preoperative DPIP block failed to provide adequate analgesia beyond 24 h post-surgery. Conclusion Preemptive bilateral DPIP block provided effective analgesia in patients undergoing CABG during surgery and in the early postoperative period. The analgesic effects of the DPIP block in the T3-4 and T4-5 intercostal spaces were comparable.

Modified Ultrasound-Guided Dorsal Quadratus Lumborum Block in Cat Cadavers.

The quadratus lumborum (QL) block is an ultrasound-guided locoregional anesthesia technique which aims to provide analgesia to the abdomen. The main objective of this study was to assess a modified ultrasound-guided dorsal QL block in cat cadavers. For this purpose, a volume of 0.4 mL kg-1 of a mixture of iopromide and methylene blue was administered between the psoas minor muscle and the vertebral body (VB) of the first lumbar vertebra, and its distribution was assessed in thirteen cat cadavers. We hypothesized that this injection point would be feasible, offering a more cranial distribution of the injectate and a more consistent staining of the truncus sympathicus. The study was divided into two phases. Phase 1 consisted of an anatomical study (three cadavers were dissected). Phase 2 consisted of the ultrasound-guided administration of the injectate and the assessment of its distribution by computed tomography and anatomical dissection. The results showed a consistent distribution of contrast media within five (4-8) VBs from T10 to L5. Methylene blue stained three (2-6) rami ventrales, affecting T11 (10%), T12 (20%), T13 (60%), L1 (85%), L2 (95%) and L3 (65%). The truncus sympathicus was dyed in all cadavers with a spread of five (3-7) VBs. Finally, the splanchnicus major nerve was stained in all cadavers (100%). These results suggest that this technique could provide analgesia to the abdominal viscera and the abdominal wall, probably with the exception of the cranial aspects of the abdominal wall.

X-ray Imaging of Two-Phase Flow Regimes in a Liquid Metal Swirling Downward Flow With Side Wall Gas Injection

The formation and behavior of gas bubbles is experimentally investigated in a liquid metal downward pipe flow, a configuration that largely corresponds to the situation in a submerged entry nozzle (SEN) in the continuous casting process in steel making. The experimental mockup is operated at room temperature using the ternary alloy GaInSn as model fluid. Argon gas is injected through an orifice located in the SEN wall. The gas distribution in the pipe is visualized by means of the X-ray radiography. The set-up is completed by an electromagnetic stirrer, which is used to create a swirling flow in the tube. Depending on the volume flow rates of the gas and the liquid metal, as well as the intensity of the swirl flow generated by the stirrer, 4 flow regimes are observed: (1) the formation of an almost stationary gas pocket in the region below the injection point without any electromagnetic stirring, (2) a twisted void zone along the side wall, (3) a straight void zone in the center of the pipe, and (4) a bubble chain in the core of the pipe flow. The experiments reveal that the wetting conditions at the inner SEN wall have a decisive influence on the resulting flow regime.

Numerical Simulation of Hydraulic Fractures Breaking through Barriers in Shale Gas Reservoir in Well YS108-H3 in the Zhaotong Shale Gas Demonstration Area

Estimating the effectiveness of hydraulic fracturing in the context of the incrfease in the shale gas demand is of great significance for enhancing shale gas production, which aims to substantially reduce fossil energy consumption and CO2 emissions. The Zhaotong national shale gas demonstration zone has complex stress structures and well-developed fracture zones, and thus it is challenging to achieve targeted reservoir segment transformation. In this paper, we construct and optimize the geometry of hydraulic fractures at different pressures considering the upper and lower barriers in hydraulic fracturing simulation experiments and numerical modeling. The numerical simulation results show that the pore pressure exhibits a stepped pattern around the fracture and an elliptical pattern near the fracture tip. During the first time of injection, the pore pressure rapidly increases to 76 MPa, dropping sharply afterward, indicating that the fracture initiation pressure is 76 MPa. During the fracture propagation, the fracture length is much greater than the fracture height and width. The fracture width is larger in the middle than on the two sides, whereas the fracture height gradually decreases at the fracture tip in the longitudinal direction until it closes and is smaller near the wellbore than at the far end. The results revealed that the fracture width at the injection point reached the maximum value of 9.05 mm, and then it gradually decreased until the fracture width at the injection point dropped to 6.33 mm at the final simulation time. The fracture broke through the upper and lower barriers due to the dominance of the effect of the interlayer principal stress difference on the fracture propagation shape, causing the hydraulic fracture to break through the upper and lower barriers. The results of the physical simulation experiment revealed that after hydraulic fracturing, multiple primary fractures were generated on the side surface of the specimen. The primary fractures extended, inducing the generation of secondary fractures. After hydraulic fracturing, the width of the primary fractures on the surface of the specimen was 0.382–0.802 mm, with maximum fracture widths of 0.802 mm and 0.239 mm, representing a decrease of 70.19% in the maximum fracture width. This work yielded an important finding, i.e., the urgent need for hydraulic fracturing adaptation promotes the three-dimensional development of a gas shale play.

RETRACTED ARTICLE: Agroinfiltration-based transient genome editing for targeting phytoene desaturase gene in kinnow mandarin (C. reticulata Blanco).

Citrus reticulata Blanco also known as kinnow mandarin is a widely grown horticultural crop in Punjab. CRISPR/Cas9 technology is being widely used for generation of varieties with increased resilience towards abiotic and biotic stresses as well as improved horticultural traits. Xanthomonas citri subsp. citri (Xcc)-mediated Agroinfiltration offers a fast and transgene-free method for the delivery of CRISPR/Cas9 constructs for systemic introduction into plants for functional genomics and expression studies. The technology is currently unexplored in kinnow mandarin. This study is aimed at establishing an efficient method of Cas9 delivery for transient knockout of PDS (phytoene desaturase) gene in kinnow mandarin. The construct pKO-119-PDS N-Cas9/sgRNA:PDS1 carrying sgRNA and Cas9 enzyme was delivered into the dorsal surface of young leaves of kinnow mandarin. The leaves showed albino patches at the point of injection within 60h. Two surfactants (Triton-X and Silwet™) were used to ease the Agroinfiltration process which resulted in variation in the expression of vector. The Sanger's analysis of the treated plants showed a substitution within the sgRNA region which resulted in change in amino acid from proline to serine. The protocol provides a feasible and an efficient method for genome editing in C. reticulata which could be helpful in future studies aimed at genome editing as well as genetic transformation.

Treating Glabellar Lines With Botulinum Toxin: Does Your Patient Need to Frown Steadily?

The variable relationship between the orbicularis supercilii and frontalis muscles may cause side effects with botulin toxin; steadily frowning is the usual recommendation. Eliminating the need to frown until all injections are over might enhance efficacy and lessen the neurotoxicity risks related to muscle exhaustion. The goal of this study was to investigate whether the digital caliper-assessed distances between the medial and lateral corrugator injection sites and the midline differed significantly in patients persistently frowning from patients resting. Seventy-six individuals with glabellar wrinkles treated with botulinum toxin in the authors' private practices for glabellar lines voluntarily contributed their retrospective data about the positions of injection sites. The investigators had freely chosen to inject the medial and lateral sections of the corrugator supercilii during persistent maximum frown or at rest. The mean differences in distances between the medial and lateral injection points and the estimated midline were clinically trivial (1.0 ± 1.28 and 1.5 ± 2.53 mm, respectively), although the distances between the relaxed and contracted medial and lateral injection sites exceeded 1.8 and 2.5 mm in 33.9% and 46.4% of patients, respectively. Distance differences, not significant before 40 years old, were statistically significant only for the lateral injections in older patients (on average, 1.9 ± 3.01 mm). The average distances from the medial and lateral injection points and the midline appear minimally different in patients who frown until all injections are over and, conversely, patients who rest. Persistently frowning might be advisable only in patients older than 40. Facial asymmetries may be a confounding factor.

Clinical application of a described erector spinae plane block for locoregional anaesthesia technique in a cow undergoing standing laparotomy

AbstractA 5‐year‐old post‐parturient Holstein Friesian cow, with a history of decreased milk production, decreased appetite and metritis, was referred for left abomasal displacement, which was corrected by right paralumbar omentopexy. After aseptic preparation of the right flank, an erector spinae plane block was performed under ultrasound guidance, using 20 mL of lidocaine 2% per point of injection, at the level of the thoracic vertebra 13, and the lumbar vertebrae 1 and 2 to provide flank anaesthesia. The cow reacted to the last 2 cm of the oblique skin incision, that corresponded to the most caudal portion of the flank. After local infiltration of the distal incision with 20 mL lidocaine 2%, the procedure was uneventful, with no anaesthesia‐related complications and no reactions to surgical stimulation. The present report describes the clinical application of the erector spinae plane block to provide flank anaesthesia in a cow undergoing standing laparotomy.

Application of Indian ink markers for locating gastric varices under endoscopic ultrasonography.

The present study aimed to investigate the accuracy of endoscopic ultrasonography (EUS) combined with Indian ink in locating target vessels of gastric varices (GVs) compared with conventional endoscopic techniques. Additionally, the characteristics of GVs under conventional endoscopy were also explored. All 50 cirrhotic patients with GVs between August 2021 and December 2022 were included in the study. Firstly, conventional endoscopy was employed to identify GVs and to record the expected injection sites. Subsequently, EUS was used to locate the perforated vessel and the injection site was them marked with India ink followed by injection with cyanoacrylate (CYA). Finally, conventional endoscopy was used to examine GVs, to identify the marker points of Indian ink and to compare whether the injection points under conventional endoscopy were consistent with those marked with Indian ink. Furthermore, patients with consistent and inconsistent distribution of endoscopic markers and injection sites were divided into two groups. EUS could detect the perforating vessels in real time and intuitively. The distribution of markers using EUS was significantly different compared with the injection points obtained by conventional endoscopy (P < 0.001). Therefore, 20 cases were allocated to the consistent group and 30 cases to the non-consistent group. 16 patients who showed red wale signs were obtained in the consistent group and 11 patients in the non-consistent group (P = 0.048). The diameter of the largest GVs was 13.5 (10-15) mm in the consistent group compared with 10 (7.5-10) mm in the non-consistent group (P = 0.006). EUS could provide the exact location of GVs, thus more accurately describing the endoscopic characteristics of the GVs. Furthermore, the red wale signs and diameter of the largest GVs obtained using conventional endoscopy were helpful in determining the location of target GVs.

Assessment of an Ultrasound-Guided Rectus Sheath Block in Foals: A Cadaveric Study

In neonatal equines, pathologies involving umbilical structures are an important cause of morbidity, and surgical removal of urachal remnants is a common procedure in clinical practice. Surgery involving the ventral abdominal wall can cause substantial pain, leading to complications and prolonged recovery. The objectives of this study were to describe a two-point bilateral ultrasound-guided rectus sheath block at the level of the umbilicus and to evaluate the extent of dye distribution in foal cadavers. Ten foal cadavers were included in the study, in which a bilateral two-point ultrasound-guided rectus sheath block was performed—one injection 5 cm cranially and a second one 5 cm caudally to the umbilicus. The injectate consisted of a mixture of iodinated contrast medium and blue dye at a volume of 0.25 mL kg−1 per injection point (total 1 mL kg−1). After the injection, computer tomography and subsequent dissection of the ventral abdominal wall were performed. The extension of the contrast medium, the number of stained nerves, and contamination of the abdominal cavity were evaluated. The cranio-caudal extension of the contrast ranged from 0.8 to 1.4 cm per milliliter of injectate. The most commonly stained ventral branches of spinal nerves were thoracic (Th) nerves 16, 17, and 18 (95%, 85%, and 80% of the nerves, respectively). Abdominal contamination was found in four animals. The results suggest that the block could provide periumbilical analgesia. Further studies with different volumes of injectate and living animals are warranted.

Dispersion effects in porous medium gravity currents experiencing local drainage

We develop a theoretical model to study (dense) two-dimensional gravity current flow in a laterally extensive porous medium experiencing leakage through a discrete fissure situated along this boundary at some finite distance from the injection point. Our model, which derives from the depth-averaged mass and buoyancy equations in conjunction with Darcy's law, considers dispersive mixing between the gravity current and the surrounding ambient by allowing two different gravity current phases. Thus do we define a bulk phase consisting of fluid whose density is close to that of the source fluid and a dispersed phase consisting of fluid whose density is close to that of the ambient. We characterize the degree of dispersion by estimating, as a function of time, the buoyancy of the dispersed phase and the separation distance between the bulk nose and the dispersed nose. On this basis, it can be shown that the amount of dispersion depends on the flow conditions upstream of the fissure, the fissure permeability and the vertical and horizontal extents of the fissure. We also show that dispersion is larger when the gravity current propagates along an inclined barrier rather than along a horizontal barrier. Model predictions are fitted against numerical simulations. The simulations in question are performed using COMSOL and consider different inclination angles and fissure and upstream flow conditions. Our study is motivated by processes related to underground $\mathrm {H}_2$ storage e.g. an irrecoverable loss of $\mathrm {H}_2$ when it is injected into the cushion gas saturating an otherwise depleted natural gas reservoir.

Gas Dispersion Coefficient Test System and Dimensionless Inversion Method for Porous Media.

Due to the complex porous media structure of the longwall gob area, it has been difficult to determine the gas dispersion coefficient of oxygen when studying spontaneous coal combustion in the gob area. In this work, we first designed an experimental device for testing the gas diffusion coefficient of porous media. Then, the distribution law of gas concentration in porous media under different particle size conditions was obtained by experiments. Subsequently, we established a dimensionless mathematical model of gas dispersion in porous media and developed a corresponding numerical simulator based on the finite volume method (FVM). The influence of the dimensionless gas dispersion coefficient on the gas concentration distribution was analyzed, and then a dimensionless inversion method of the gas dispersion coefficient was summarized and put forward. Finally, we obtained the values of the gas dispersion coefficient in the experimental device under different particle size conditions by inversion and discussed its effect on the gas dispersion behavior in porous media. The results show that (1) the distribution of gas concentration obtained from the experimental test and numerical simulation is consistent, which verifies the reliability of our work; (2) the dimensionless gas concentration is the highest near the injection point and gradually decreases along the depth and both sides of the test container; (3) with the increase of the dimensionless gas dispersion coefficient, the distance required for uniform gas mixing in the test container is gradually shortened and the gas dispersion coverage is wider; and (4) the larger pore space facilitates the dispersion behavior of the gas, and the gas dispersion coefficient shows a parabolic trend with the increase of porous medium particle size.

Ultrasound-guided caudal quadratus lumborum block combined with the greater ischiatic notch plane block as motor-protective analgesia for the pelvic limb in dogs

ObjectiveTo develop an ultrasound-guided caudal quadratus lumborum block (C-QLB) technique in canine cadavers and to compare sensory and motor blockade resulting from the combination of ultrasound-guided greater ischiatic notch (GIN) plane and C-QLB approaches (GIN-CQLB group) versus a lumbosacral plexus (LSP group) approach [combination of lateral pre-iliac (LPI) and parasacral (PS) techniques] in dogs. Study designDescriptive anatomical study and prospective randomized, blinded, experimental crossover trial. AnimalsA total of six canine cadavers and six adult Beagle dogs. MethodsPhase I: following ultrasound-guided C-QLB injections of 0.3 mL kg–1 of dye, using the interfascial plane located lateral to the quadratus lumborum muscle at the level of the sixth lumbar vertebra (L6) as injection point, the spread of injectate and nerve staining was evaluated using gross anatomical dissection. Phase II: sensory and motor blockade achieved with the GIN-CQLB or LSP blocks in Beagle dogs were evaluated and compared. The assigned technique was performed with 2% lidocaine: 0.2 mL kg–1 for the GIN and PS approaches and 0.3 mL kg–1 for the C-QLB and LPI approaches. ResultsDissection revealed distribution of dye around the lumbar hypaxial musculature, extending into the paravertebral spaces, with staining of 3 (2–4) [median (interquartile range)] spinal nerves, spanning L3 to L6. The median motor blockade in the GIN-CQLB and LSP groups was 7 (7–8) versus 16 (10–16) (p = 0.026), whereas the median sensory blockade was 5 (4–5) versus 3 (3–3) (p = 0.025), respectively. Conclusion and clinical significanceThe GIN-CQLB approach desensitized the thigh dermatomes effectively. Compared with the LSP approaches, GIN-CQLB exhibits a motor-protective effect by preserving tonic muscle function.

Solutions to increase the C-2P well production performance at X oil field, Block 09-2

The well C-2P had its first oil production in July 2008, the initial production rate is 3,000 barrels/day. Due to the reservoir pressure depletion in 2017-2018, the well faced difficulties in kicking off to open the well for production. In November 2018, when the C-5PST2 well was put into production, the C-2P well was not produced by natural flowing. The kicking off has been attempted many times but the well still won't flow. The main reason the well couldn’t flow is due to low reservoir pressure which has not enough energy to push all the fluid in the well to the surface after each well shutdown. The flow assurance study shows, at the reservoir pressure of 3,000 Psi, and tubing head pressure of 950 Psi, the well can’t flow naturally. In addition, with the reservoir pressure of 3,000 psia and applying the gaslift injection rate of 1.0 MMscf/d, injection point at 3,030 mTVD, the well flowed. The continuous gaslift pump helps maintain the well's production in case the reservoir pressure drops even lower to 2,000 psi, and at the same time, optimizing the gaslift pump flow helps to increase the well production by 100-300 barrels of oil/day. When the reservoir pressure drops lower, it is necessary to lower the gaslift valve deeper to continue kicking off the well and maintain the well production performance. On the other hand, due to the lack of a gaslift valve for the original design of C-2P well so it's necessary to have gaslift tubing pack off in order to bring the well back to production, maintain stability and improve production. This paper, therefore, presents the results of the research on the solution to increase the production output of the C-2P well located in X oil field used gaslift valve combining with the tubing pack off. Results of the research on the application of solution show that the well's production output has increased significantly (0.354 million barrels) in the first year of applying the solution.

Alternative sorbents for mercury capture in flue gas from lignite combustion

This paper presents an experimental study of two of alternative sorbents for mercury capture from the lignite combustion flue gas. The sorbents are based on calcium hydroxide and aluminosilicate, using different modifications. A commercially available activated carbon (AC) with bromine impregnation was selected as the reference sorbent. This sorbent is a state-of-the-art solution for mercury removal in industrial combustion facilities. However, its application is costly for power plants because of the market price of the AC and because the presence of carbon in the fly ash can complicate its further use, which gives a strong motivation for exploring new alternatives. Experimental investigation was carried out in a 500 kW pilot-scale bubbling fluidized bed combustor using a lignite with naturally high mercury content. A injection system of our own design and construction was used to supply the sorbents to the flue gas downstream of the combustor at a flow rate in the range of 100–500 mg/m3N of the flue gas. Continuous measurement of mercury concentration was used upstream the sorbent injection and downstream the fabric filter, simultaneously. Different sorbent injection rates and flue gas temperatures at the sorbent injection point were examined.The mercury capture ratio was evaluated considering the Hg balance in the combustor. It was shown that the mercury self-capture by the fly ash in the fluidized bed combustion system varies approximately from 30 to 90 %, depending on the SO2 concentration. The Hg capture ratio for calcium hydroxide was in a range of approximately 15–25 %, while for aluminosilicate it was 25–45 %, determined by the actual conditions of the flue gas and the initial Hg concentration. This is in the range of the reference AC, which typically reaches from 25 – 95%. The increased injection rate of the sorbents was reflected in the Hg capture ratio, but its promotion was observed only in the case of the aluminosilicate sorbent. A correlation of the Hg capture ratio with the flue gas temperature at the injection point was also clearly identified only for the aluminosilicate sorbent, when an increase in the temperature led to increasing in the capture ratio.

Early and long-distance uptake by Eucalyptus grandis of N, K and Ca tracers injected down to a depth of 7 m

Eucalyptus plantations are commonly fertilized at planting to sustain high biomass production over successive rotations in nutrient-poor soils. However, the dynamics of nutrient uptake by tree roots in the early stages of stand development, depending on the lateral distance from the trees and the depth in the soil, are poorly documented. We assessed the potential uptake of N, K and Ca, from 6 to 18 months after planting, by Eucalyptus grandis trees depending on: i) the lateral distance from the tracer injection point and ii) the depth in the soil. At 6 months after planting, we injected 15NO3–, Rb+, Sr2+ and Cs+ tracers at depths of 1, 3, 5, and 7 m, respectively. Recently expanded leaves were then sampled monthly on 16 target E. grandis trees located at lateral distances ranging from 0.75 to 11.1 m from the injection points, and on 4 more distant E. grandis control trees; 15N contents (atom %) and concentrations of Rb, Cs and Sr in the leaves were determined at each sampling date, and compared to those of control trees to detect the dates of tracer uptake for each individual. A LOESS model was applied to account for the temporal trend and inter-tree variability among the control trees. Tracer uptake by a target tree was detected if the measurements exceeded the upper limit of the prediction interval (α = 0.005) generated by the model. Only the 6 target trees located within 2.0 m from the injection point took up the 15NO3– tracer. However, Rb+, Sr2+ and Cs+ tracers were taken up to lateral distances of approx. 11 m from the injection point. Tracer uptake occurred as early as 9, 7, 8 and 9 months after planting for 15NO3–, Rb+, Sr2+ and Cs+, respectively. Four trees located within 2.8 m from the injection point took up the 3 cation tracers, injected between the depths of 3 m and 7 m. All but one of the target trees took up at least one cation tracer. The potential of Eucalyptus trees to take up nutrients early, at long distance and at depth, can be promoted by silvicultural practices enhancing rapid root development after planting, as subsoiling in commercial plantations and large planting holes in smallholder plantations. Our results also suggest that fertilization could be applied only once at planting in Eucalyptus stands established on deep tropical soils, with low risks of nutrient losses by deep drainage.

The Effect of Multiple Cycles of Surfactant-Alternating-Gas Process on Foam Transient Flow and Propagation in a Homogeneous Sandstone

Summary Years of laboratory studies and field tests show that there is still uncertainty about the ability of foam to propagate deep into a reservoir. Many factors have been identified as potential causes of nonpropagation, the most concerning being the lack of sufficient pressure gradient required to propagate foam at locations far from the point of injection. Most researchers that investigated foam propagation did so by coinjecting surfactant and gas. Coinjection offers limited information about transient foam processes due to limitations in the experimental methods needed to measure foam dynamics during transient flow. Foam injection by surfactant-alternating-gas (SAG) has proven to be more effective and common in field application. Repeated drainage and imbibition cycle offer a more favorable condition for the quick generation of foam. Foam can also be propagated at a lower pressure gradient in SAG mode. The objective of this study is to experimentally investigate how transient foam dynamics (trapping, mobilization, and bubble texture) change with multiple cycles of SAG and also with distance from the point of injection. A pair of X-ray source and receiver, differential pressure transducers, and electrical resistance sensors were placed along a 27-cm long, homogeneous, and high-permeability (KL = 70 md) Berea sandstone core. Foam was then generated in situ by SAG injection and allowed to propagate through the core sample under a capillary displacement by brine (brine injection rate = 0.5 cm3/min, Nca = 3×10-7). By use of a novel analytical method on coreflood data obtained from axial pressure and saturation sensors, we obtained trapped foam saturation, in-situ foam flow rates, apparent viscosities, and inferred qualitative foam texture at different core sections. We then observed the following: (i) Maximum trapped foam is uniform across the core sections, with saturation ranging from 47% to 52%. At the vicinity of foam injection, foam apparent viscosity is dominantly caused by gas trapping. At locations farther away, foam apparent viscosity is dominated by both gas trapping and refinement of foam texture. (ii) Cyclic injection of foam further enhances the refinement of foam texture. (iii) Textural refinement increases foam apparent viscosity as it propagates away from the point of injection. (iv) As the foam strength increases, the average gas flow rate in the core sample decreases from 0.5 cm3/min to 0.06 cm3/min. (v) There is no stagnation of foam as remobilization of trapped gas occurs during each cycle at an average flow rate of 0.002 cm3/min.

Comprehensive numerical study of sequential injection of SiO2-nanofluids for enhanced oil recovery

Improving the efficiency of oil production is an important element in reducing the carbon footprint of the oil industry. One of the methods for increasing the efficiency of oil recovery is the use of oil flooding using solutions of various chemical reagents. The paper presents a computational investigation of the oil recovery from a porous micromodel using a nanofluid during sequential injection of water-SiO2 nanofluid-water. The effect of the nanosuspension concentration, duration of injection of the nanosuspension, the starting time point of nanosuspension injection, as well as the influence of oil viscosity on the oil recovery during sequential injection of main displacement fluid and nanosuspensions was investigated. Such a systematic study was performed for the first time. It was found that injection of three pore volumes of nanosuspension increases oil recovery factor by 1.5 times compared to injection of three pore volumes of water. It has been established that, from a practical point of view, it is most effective to increase oil recovery by starting the injection of nanosuspension after injecting two pore volumes of water. This case leads to an increase in recovery factor by 1.35 times compared to the injection of three pore volumes of water. As a result, it was shown that employing sequential injection allows obtaining an oil recovery factor comparable to that corresponding to oil recovery by nanosuspension. Thus, sequential injection makes it possible to significantly reduce the amount of nanoparticles during injection of nanosuspensions, while maintaining a high beneficial effect on the ORF. This is an important positive fact for the further development of this method of increasing oil recovery.

Flow regime evolution mechanism and falling flux prediction model for bypass injection of viscous liquid in vertical T-junction

The gas–liquid two-phase flow in T-junction serves as a fundamental theoretical foundation for studying mass and heat transfer laws in industrial applications, including oil and gas resource development and material mixing in the chemical industry. We designed a T-junction pipeline consisting of a vertical gas flow pipe and a horizontal liquid injection pipe and conducted experiments to investigate gas–liquid two-phase flow with liquid bypass injection. The experimental results indicate that there are two critical states for the downward flow of liquid at the injection point at different gas velocities: Critical Downward Flow(CDF) and All Downward Flow(ADF). Based on liquid falling state and response law of falling flux, the liquid falling conditions were categorized into three regions: region without liquid falling (flux ratio = 0), region of all liquid falling (flux ratio = 1) and transition region(flux ratio from 0 to 1). Through analyzing the dynamic characteristics of gas–liquid two-phase flow at the connection point and considering the zero shear stress state of the pipe wall and flow pattern transition, a CDF criterion for the liquid was established. The flooding state of gas–liquid countercurrent was used as the limit condition for ADF, and a criterion for ADF was developed based on experimental data. Under varying liquid viscosity conditions, compared with experimental data, the error of the CDF criterion model is less than 5 %, and the error of ADF criterion model is less than 15 %. A liquid falling flux prediction model was established based on the two extreme states of liquid falling, and its accuracy was verified through experimental results, challenging the existing theoretical criterion of liquid falling flux ratio being limited to “either 0 or 1”.