Horizontal Fracture Research Articles

Immediate fixed temporization with a natural tooth crown pontic and fiber-reinforced composite following horizontal root fracture: A case report

Anterior tooth loss can significantly affect self-esteem, particularly in young individuals. Traditional treatments like removable prostheses often fail to meet aesthetic and functional standards. Using the patient’s natural tooth as a temporary bridge offers a perfect match in size, shape, and color, with psychological benefits. In this case, a 24-year-old male with a fractured maxillary left central incisor underwent tooth extraction. The extracted tooth was cleaned, reshaped with composite resin, and attached to adjacent teeth using fiber-reinforced composite. This technique provided immediate restoration with an aesthetically pleasing ovate pontic design that supported natural gingival health. The patient reported satisfaction with the aesthetic and functional outcome after one month. Utilizing the natural tooth as a pontic is cost-effective, minimally invasive, and preserves future treatment options, making it an ideal temporary solution for anterior tooth loss.

Multicenter External Validation of the Accuracy of Computed Tomography Criteria for Detecting Thoracolumbar Posterior Ligamentous Complex Injury.

Recent studies have proposed computed tomography (CT) criteria for posterior ligamentous complex (PLC) injury: disrupted if ≥2 CT findings, indeterminate if single finding, and intact if 0 CT findings. The study aims to validate the CT criteria for PLC injury externally. Three level 1 trauma centers enrolled 614 consecutive patients with acute thoracolumbar fractures (T1-L5) who received CT and MRI. Three reviewers from each center assessed CT for facet joint malalignment, horizontal laminar fracture, spinous process fracture, and interspinous widening and MRI for disrupted PLC, defined as black stripe discontinuity. The primary outcome is the diagnostic accuracy of CT criteria (0, 1, ≥2 findings) in detecting disrupted PLC on MRI using all CT readings. A subgroup analysis was performed for each participating center and reviewer. The inter-reader agreement on PLC status on MRI and CT criteria was assessed using Fleiss Kappa (k). The positive predictive value for PLC injury was 0 findings 3%, single positive CT 43%, and ≥2 CT findings in 94%. The accuracy measures were consistent across various centers and reviewers. The area under the curve for ≥1 CT finding in detecting PLC injury ranged from 90% to 97%, indicating excellent discrimination for all centers. The inter-reader k on PLC status by MRI and overall CT findings was substantial (k > 0.60). This study externally validates the previously proposed CT criteria for PLC injury. A total of ≥2 positive CT findings or 0 CT findings can be used as criteria for a disrupted PLC (B-type injury) or intact PLC (A-type injuries), respectively, without added MRI. A single CT finding implies indeterminate PLC status and the need for further MRI assessment. The CT criteria will potentially guide MRI indications and treatment decisions for neurologically intact thoracolumbar burst fractures.

Experimental investigation on enhancing oil recovery of volcanic fractured oil reservoir by gas injection huff-n-puff considering gas diffusion

The pore structure of volcanic fractured oil reservoirs is complicated, and the traditional gas displacement and waterflooding are not ideal. In this paper, the pore structure characteristics of volcanic rock were analyzed. Then, the diffusion procedure of CO2 and natural gas in saturated oil porous media was analyzed by pressure drop method. Finally, huff-n-puff experiments of CO2 and natural gas were conducted to analyze factors on the recovery factor (RF), and the oil mobilization pattern was quantitatively characterized. By huff-n-puff, we mean injecting gas from one end and then soaking it for a period of time before producing oil, utilizing pressure-driven and physicochemical reactions to affect the oil. The results show that the pore size distribution range is large. The diffusion of CO2 and natural gas can be divided into three stages: rapid diffusion, slow diffusion and equilibrium, and the diffusion coefficient of CO2 is 10 times that of natural gas under same condition. Compared with vertical fractures and horizontal fractures, reticulate fractures have more influence on gas diffusion coefficient. After 6 cycles, the RF of CO2 is 15% higher than that of natural gas, and the contribution of the first 4 cycles to the RF is 91.38%. In addition, CO2 huff-n-puff primarily mobilizes oil in medium (0.1 μm < r < 1 μm) and large (r > 1 μm) pores. These research results can provide a good theoretical guidance for the efficient development of VFOR and CO2 sequestration.

Conservative Management of Horizontal Root Fracture: ACase Report.

In cases where permanent teeth have closed apices and completely erupted roots, the probability of root fractures is increased due to the stable support given by the adjacent bone and periodontal tissues. Fractures have the potential to affect several dental structures, including the pulp, dentin, cementum, bone, and periodontal tissues. In cases of horizontal root fractures (HRF), the apical section typically maintains vitality; however, the present case presented an unusual apex necrosis. Given the patient's age and tooth stability, traditional apical surgery was deemed inappropriate. Instead, a conservative treatment approach was chosen to preserve the tooth. This case report details the management and a 2-year follow-up of a maxillary central incisor exhibiting a HRF and apical necrosis, successfully addressed through the application of Mineral Trioxide Aggregate (MTA) in the both apical and coronal segments. Using MTA prevented apical surgery in cases of apex necrosis accompanied by HRF.

Use of mineral trioxide aggregate in the treatment of horizontal root fracture with a 4-year follow-up: case report

Use of mineral trioxide aggregate in the treatment of horizontal root fracture with a 4-year follow-up: case report

Numerical study of influence of karst fracture water on heat transfer performance of borehole heat exchanger

Groundwater flow within karst fractures can significantly enhance the heat exchange efficiency between a borehole heat exchanger (BHE) and the surrounding rock. The development of artificial fractures to intensify heat transfer between the BHE and rock has emerged as a promising direction in geothermal exploration. This study presents a three-dimensional finite element simulation model that integrates fracture flow with BHE heat transfer, accounting for various characteristics of horizontal fractures. Data analysis was conducted using range analysis and multi-criteria comprehensive evaluation, based on the principles of orthogonal experiments. The results indicate: (i) Fracture water flow substantially improves BHE heat transfer performance in summer, with even the lowest-performing configuration in the orthogonal test showing a 5.36 % increase in heat transfer per unit length of the BHE (HPLU) compared to the natural control group without fractures; (ii) The influence of different fracture characteristics on BHE heat transfer performance follows this order: fracture water velocity > fracture aperture > fracture depth > fracture flow direction > fracture water temperature; (iii) The optimal configuration enhances HPLU by 16.95 % over the natural control group, demonstrating that developing well-designed artificial fractures in karst regions can substantially improve BHE heat transfer efficiency.

Stress shadow effects in multistage horizontal hydrofracturing of tight reservoirs: a numerical analysis considering perforation cluster spacings and fracturing sequences

AbstractMultistage horizontal fracturing technology of reservoirs has been widely used to enhance tight hydrocarbon resource recovery. Determining the proper perforation cluster spacing is crucial to developing a complex fracture network that connects natural rock fractures and facilitates gas flow in reservoirs. The stress shadow effect that occurs between multiple clusters has a significant effect on the development of the fracture network in reservoirs. The quantification of the stress shadow effect and its influences on the development of fracture networks has not been resolved satisfactorily due to experimental and numerical difficulties with detecting and identifying crack propagation and intersection in deep reservoirs. In this study, we used an adaptive finite element-discrete element method to analyze crack propagation and intersection in tight shale reservoirs by altering perforation spacings and fracture sequences. The effects of five perforation cluster spacings using sequential, simultaneous and parallel fracturing techniques were compared. The non-linear properties of shales, hydromechanical coupling and fluid leak-off effects, proppant transport, dual-rupture criteria of strength and energy, and intersection of hydraulic fractures were taken into account in the simulation. The areas affected by the stress shadow and the optimum perforation cluster spacing in terms of hydraulic fracture propagation lengths, volumes, and microseismic magnitudes were evaluated when adopting different fracturing methods. This study extends the understanding of the impact of the different independent factors that contribute to the stress shadow effect and, therefore, provides new information to help guide wellbore completion design in horizontal fracturing wells.

New enhanced hybrid glulam-framed OSB wall for tall timber buildings

The article covers the cyclic lateral performance of a new hybrid timber shear wall called GLUlam-Frame OSB (GLUFO), composed of glulam frames connected to OSB (Oriented-Strand Board) sheathing panels and conventional nails. The key constructive detail of this new wall relies in that the OSB sheathings are embedded at grooved glulam members, which largely enhance the lateral strength capacity and stiffness of the element than the conventional light-frame timber or Cross-Laminated Timber (CLT) walls. The experimental campaign includes the Framing-to-Panel (F2P) connections and full-scale wall testing under cyclic loads. The wall failed due to a horizontal tensile fracture along the top beam, mainly caused by insufficient nail spacing. However, the wall reached a lateral drift of 1.48 % and a ductility of 5.8, which could have been higher if the failure had not occurred. Moreover, the proposed wall is three times stronger and stiffer than a conventional CLT wall and comprises one-fourth of the wood amount (0.89 m3) compared to a CLT wall of similar strength capacity. Finally, the proposed wall was characterized by a nonlinear macro-Finite Element (FE) model, whose F2P connections were simulated with the MSTEW hysteretic model, and three Single-Degree-Of-Freedom (SDOF) models, each with a different hysteretic model from the literature (MSTEW, DowelType, and ASPID). All numerical models show an error of up to 8 % for the lateral strength capacity, while the SDOF models are more precise for the energy dissipation prediction, with a error lower than 4.3 % and R2 for their history over 99.5 %. Hence, both numerical models provide a feasible alternative to simulate this new wall prototype.

MULTICENTER EXTERNAL VALIDATION OF THE ACCURACY OF COMPUTED TOMOGRAPHY CRITERIA FOR DETECTING THORACOLUMBAR POSTERIOR LIGAMENTOUS COMPLEX INJURY

Background and Objective Recent studies have proposed computed tomography (CT) criteria for posterior ligamentous complex (PLC) injury: disrupted if ? 2 CT findings, indeterminate if single finding, and intact if 0 CT findings. The study aims to validate the CT criteria for PLC injury externally. Methods Three level 1 trauma centers enrolled 614 consecutive patients with acute thoracolumbar fractures (T1- L5) who received Computed tomography (CT) and magnetic resonance imaging (MRI). Three reviewers from each center were the patients from the respective center for sessed CT for facet joint malalignment, horizontal laminar fracture, spinous process fracture, and interspinous widening and MRI for disrupted PLC. The primary outcome is the diagnostic accuracy of CT criteria (0,1, ? 2 findings) in detecting disrupted PLC on MRI using all CT readings. Subgroup analysis for each participating center and reviewer was done. The inter-reader agreement on PLC status on MRI and CT criteria was assessed using Fleiss Kappa (k). Results The positive predictive value (PPV) for PLC injury was 0 findings, 3%; single positive CT, 43%; ? 2 CT findings, 94%, and was consistent among different centers and reviewers. The AUC for ? 1 CT findings in detecting PLC injury ranged from 90% to 97%, indicating excellent discrimination for all centers. The inter-reader k on PLC status by MRI and CT criteria was substantial (k >0.60). Conclusions This study externally validates the previously proposed CT criteria for PLC injury. ? 2 positive CT findings or 0 CT findings can be used as criteria for a disrupted PLC (B-type injury) or intact PLC (A-type injuries), respectively, without added MRI. A single CT finding implies indeterminate PLC status and the need for further MRI assessment. The CT criteria will potentially guide MRI indications and treatment decisions for burst fractures in patients without neurological impairment.

Effect of Thick–Hard Main Roof Fracturing on the Spatiotemporal Evolution of Overburden Fractures

Gas gushing and the co-mining of coal and gas outbursts are common disasters in coal mines. The weakening of thick–hard main roof fracturing can effectively alleviate the gas overrun in the initial mining stage. Four numerical simulation schemes were designed to determine the optimal fracturing treatment scheme for the gas overrun problem in the initial mining stage of the 6505# working face in the Huanghou Coal Mine. Compared with the scheme of the non-fracturing main roof, the weakening of the main roof fracturing could alleviate the concentration of advanced abutment stress. The fissure ratio of the overburden was solved by the binary method, and the dominant channels of gas migration and their morphological evolution under different fracturing schemes were obtained. On this basis, the permeability model of “permeability–fissure ratio–fractal dimension” was established. The results show that the overburden fracture network of the horizontal fracturing scheme has a larger fractal dimension, indicating that the overburden fracture under the scheme is more fully developed and more conducive to gas migration. The research results provide valuable reference for the design of the gas extraction scheme.

Evaluation of recoverable reserves based on dynamic data for horizontal wells in unconventional oil reservoir

Unconventional reservoirs are often exploited by horizontal well volumetric fracturing. Recoverable reserves are an important basis for evaluating the development effect of oil reservoirs. In this study, an evaluation index of recoverable reserves was proposed which based on the mathematical statistics method. A mathematical model for the index and the standardized calculation process were established. The dynamic data in the study was from the RA tight reservoir of Songliao basin. The results show that: (1) Horizontal wells production can be categorized into three distinct groups based on daily oil production and cumulative oil production (Np), showing no obvious "L"-shaped decrease. (2) A power function is presented by the correlation between Np logarithm (logNp) and production time, with a distinct inflection point in the curve. As the evaluation index of recoverable reserves, the Np corresponding to the inflection point is taken. (3) After verification, the derivative value of logNp corresponding to the inflection point is approximately 0, and the derivative parameter m represents the characteristics of different regions. Statistically, the study area m is 0.0003. (4) The recoverable reserves evaluation indexes of all known horizontal wells that can reflect the real production capacity were calculated. The recoverable reserves of the three blocks in the study area were successively S1 block, S3 block and S2 block from high to low. (5) According to the relationship between cumulative oil production, initial daily production and the evaluation index, the evaluation index is only suitable for the characterization of recoverable reserves in the middle and late production of tight oil wells, but not suitable for the characterization of recoverable reserves in the early production of wells.

Numerical simulation of solid diverting particles transport and plugging in large-scale hydraulic fracture

Diversion technology, also known as temporary plugging technology, has become an integral part of hydraulic fracturing in unconventional reservoirs. The solid diverting particles are a common type of chemical diverting agents used in horizontal well multistage fracturing. The transport and plugging of solid diverting particles within the fractures are crucial physical processes in the far-field diversion technology. In this study, in order to clarify the formation of the plugging layer by solid diverting particles in large-scale hydraulic fracture and to offer insights for the quantitative optimization of far-field diversion technology (FFD), an enhanced simplified two-fluid model within the Euler-Euler framework is employed to simulate the transport and plugging process of solid diverting particles within the fracture. And the numerical schemes of the front settlement region, the plugging layer formation region and the rear settlement region are also optimized. The proposed model is verified through comparison with experimental results from visual fracture test device. Based on the numerical results across various particle, pumping and fracture parameters, our findings indicate that: (1) The duration required to form a complete plugging layer can be reduced to 3%∼20% by increasing injection concentration, injection rate, and fracturing fluid viscosity; (2) Increasing the injection concentration (from 10kg/m3 to 30kg/m3) significantly enhances the length of the plugging layer by about 1∼16 times, compensating for the inability to achieve a complete plugging layer with smaller particle sizes. Merely increasing the injection rate alone (from 0.35m3/min to 0.80m3/min) does not remedy the inability of small particles to form a complete plugging layer under identical plugging conditions. Excessive fracturing fluid viscosity (higher than 6mPa·s) impedes the formation of a complete plugging layer with smaller particles. High fracturing fluid leak-off rate (higher than 2.5×10-7m/s) markedly reduces the length of the plugging layer by about 37%∼44%; (3) Achieving a high close packing degree of particles within the plugging layer is facilitated by increasing injection concentration, increasing injection rate, and reducing fluid viscosity; (4) The abrupt variation in fracture width or height along the fracture length affects up to about 18% of the length of the plugging layer at the top of fracture. To ensure large length of the plugging layer at the top of fracture and high close packing degree of particles within the plugging layer, we recommend injection concentration above 10kg/m3, fracturing fluid viscosity below 6mPa·s, and injection rate exceeding 0.35m3/min. For particle size less than 1.8mm, we suggest injection concentration above 20kg/m3, and fracturing fluid viscosity not exceeding 3mPa·s.

Numerical Modeling of Hydraulic Fracturing Interference in Multi-Layer Shale Oil Wells

Multi-layer horizontal well development and hydraulic fracturing are key techniques for enhancing production from shale oil reservoirs. During well development, the fracturing performance and well-pad production are affected by depletion-induced stress changes. Previous studies generally focused on the stress and fracturing interference within the horizontal layers, and the infilled multi-layer development was not thoroughly investigated. This study introduces a modeling workflow based on finite element and displacement discontinuity methods that accounts for dynamic porous media flow, geomechanics, and hydraulic fracturing modeling. It quantitatively characterizes the in situ stress alteration in various layers caused by the historical production of parent wells and quantifies the hydraulic fracturing interference in infill wells. In situ stress changes and reorientation and the non-planar propagation of hydraulic fractures were simulated. Thus, the workflow characterizes infill-well fracturing interferences in shale oil reservoirs developed by multi-layer horizontal wells. Non-planar fracturing in infill wells is affected by the parent-well history production, infilling layers, and cluster number. They also affect principal stress reorientations and reversal of the fracturing paths. Interwell interference can be decreased by optimizing the infilling layer, infill-well fracturing timing, and cluster numbers. This study extends the numerical investigation of interwell fracturing interference to multi-layer development.

Reflection coefficients for non-welded interface between orthorhombic half-spaces under initial stress

SUMMARY Complex oil and gas reservoirs represented by orthorhombic shale usually have the characteristics of strong anisotropy, wide distribution of non-welded interfaces (i.e. particular boundaries caused by horizontal bedding or fracture development), and ubiquitous initial stress effects. The knowledge of their seismic response characteristics plays an essential role in hydrocarbon exploration in stressed shale reservoirs. However, seismic wave reflection in the orthorhombic media under initial stress remains unclear. To address this issue, we used the theories of acoustoelasticity and elastic anisotropy to derive a stress-dependent effective elastic stiffness tensor. At the same time, we obtain the wave velocity and polarization characteristics directly by solving the Christoffel equation. According to the linear slip theory, we further constructed the exact reflection and transmission coefficient equations for the non-welded interface between isotropic and orthorhombic half-spaces under the initial stress. The effects of the non-welded interface on seismic wave velocity and reflection and transmission coefficients were systematically analysed. Meanwhile, we characterize the law of P-wave reflection coefficient effected by elastic coefficients. Our equations and results potentially lay an equation foundation for orthorhombic reservoirs in high-stress fields and are essential in orthorhombic reservoirs in high-stress geophysical exploration.

Simulation Study on Reservoir Stimulation of Multihorizontal Wells for Gas Hydrate Production in Low-Permeability Reservoirs.

The feasibility of hydrate exploitation technology has been verified by two rounds of trial productions in the South China Sea, but it is also faced with the problem of low gas production efficiency. Therefore, this paper proposed four different hydrate production cases with multihorizontal wells and established simulation models. Then, the influence patterns of reservoir stimulation and offset distances on hydrate dissociation, saturation change, and pressure distribution were studied. To understand hydrate dissociation behaviors and production performances, the coupling effects of multihorizontal wells were discussed. Through simulation, the following conclusions could be drawn: (1) hydrate reservoir stimulation could effectively increase gas production. In these four production models, the cumulative gas production in Case C (multihorizontal wells + reservoir stimulation) was 5.27 times that of Case A (only multihorizontal wells) in 330 days. However, in Case D with screen completions, the gas output was 15.58% less compared with Case C. (2) Different offset distances of horizontal wells had a relatively minor impact on the cumulative gas yield and daily gas capacity. In addition, the variation range of hydrate saturation changed with offset distances of horizontal wells, indicating that hydrate dissociation occurred mainly around horizontal wells and fractures. (3) Considering interwells coupling, the daily gas rate and cumulative gas production of inner wells were higher than outer wells, and the cumulative gas volume increased by 6.4% in 330 days. Temporally and spatially, the hydrate saturation variation between wells was significantly faster than the outward expansion from the horizontal wells. Moreover, nearer to the axis of the horizontal wells, the variation in the hydrate saturation was more pronounced. These results could provide theoretical data to optimize marine hydrate development with multihorizontal wells.

Analysis of the Impact of Clusters on Productivity of Multi-Fracturing Horizontal Well in Shale Gas

Shale gas reservoirs with nanoporous media have become one of the primary resources for natural gas development. The nanopore diameters of shale reservoirs range from 5 to 200 nm, with permeability ranging from 1 × 10−9 to 1 × 10−6 μm2. The natural gas production from shale gas reservoirs is low, necessitating the use of multi-stage hydraulic fracturing in horizontal wells. Segmented multi-cluster perforation fracturing is an effective method for shale gas extraction in these wells. The number of clusters significantly impacts the productivity of horizontal wells. Therefore, it is essential to analyze the impact of cluster numbers on fracture productivity in shale gas reservoir development. In this study, the equivalent flow resistance method was applied to establish a productivity model for multi-stage hydraulic fracturing horizontal wells in shale gas reservoirs considering diffusion and slip. An approximate analytical solution was obtained, and the effects of cluster length, diffusion coefficient, and fracture network permeability on productivity were analyzed. The results show that gas production gradually increases with the increase in the number of clusters and cluster length. However, as the number of clusters increases, the interference between clusters leads to a decrease in the productivity of individual clusters. As the fracture permeability, fracture network permeability, and diffusion coefficient increase, shale gas production also gradually increases. The permeability of the fracture network has the greatest impact on productivity. These research results are beneficial for the design of clusters in horizontal well fracturing and are of great importance for the development and production of shale gas reservoirs.

Laboratory and numerical investigations on land-sourced solute transport in coastal fractured aquifers

Land-based pollutants threaten coastal aquifers, highlighting the need to protect groundwater and nearshore marine ecosystems. While aquifer heterogeneity has been recognized as a significant factor affecting solute behavior, the impact of fractures on land-sourced solute transport in coastal aquifers remains unclear. This study attempted to address this issue through laboratory experiments and discrete fracture matrix (DFM) models. The impact of horizontal fractures on the temporal and spatial characteristics of solute transport, spreading, and discharge under seawater intrusion was analyzed based on variations in fracture position and length. The results show that fractures/low-velocity zones (LVZ) can accelerate/delay solutes, dividing them into different transport modes and enhancing/prolonging their spreading/discharge duration. Changes in fracture position and length also affect its transport acceleration and path deviation abilities, which ultimately determine when solute discharge occurs. The mixing zone and unsaturated zone, in addition to the LVZ, hinder solute transport, reducing the rate and delaying the end of solute discharge. Meanwhile, fractures facilitate solute transport into the saltwater wedge, expanding the solute discharge zone. However, if solutes are initially within the LVZ, their entry into the fracture rely on their distance from the fracture's near-land edge and the size of the fracture's convergence zone.

Immediate and late treatment of horizontal root fractures

Immediate and late treatment of horizontal root fractures

Immature Central Incisors With Horizontal Root Fracture:36 Months Follow-up

Immature Central Incisors With Horizontal Root Fracture:36 Months Follow-up

CT-Assisted Management with Biodentine Obturation and Aesthetic Rehabilitation of a Geminated Maxillary Central Incisor with Mid-Root Fracture: A Rare Case Report

Gemination, a rare aberration in tooth development, results from the incomplete division of one tooth germ into two. In this case report, a true geminated permanent maxillary central incisor tooth with a horizontal mid-root fracture is successfully treated by non-surgical endodontic treatment. To elucidate the intricate root canal anatomy of this rare geminated incisor, we employed computed tomography imaging technology, enhancing our understanding of this complex case. Utilizing biodentine for obturation proved pivotal, as its capacity to accelerate reparative dentin formation facilitated prompt healing, particularly beneficial in fracture cases. This was followed by aesthetic rehabilitation to achieve a pleasing mesio-distal dimension for both the central incisors using a zirconia-reinforced porcelain crowns. Keywords: Computed Tomography (CT), Gemination, Horizontal root fracture, Biodentine Obturation