Fracturing Technique Research Articles

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.

The long-term results of treating radial neck fractures in children with the Metaizeau technique

Purpose: Radial neck fractures in children are rare, representing less than 1% of all pediatric fractures. While conservative treatments are often sufficient, displaced fractures may require closed or open reduction. The Metaizeau technique is widely accepted for closed reduction and internal fixation. This study aims to assess the long-term functional and radiological outcomes of this technique and identify any complications that may arise. Methods: This retrospective study analyzed 22 pediatric patients treated with the Metaizeau technique for proximal radius fractures between 2005 and 2018. Data on demographics, preoperative radiographs, and postoperative complications were reviewed. Outcomes were evaluated using radiographic and functional measures, including grip strength, the Mayo elbow performance score (MEPS), and the Tibone and Stolz classification. Results: The mean age at the time of injury was 9.9 years, with a mean follow-up period of 139 months (range: 72–213 months). Patients were classified as Judet type 3 ( n = 9), type 4a ( n = 9), or type 4b ( n = 4). The functional outcomes showed a mean MEPS score of 99 (range: 90–100), with 86% of patients achieving excellent results according to the Tibone and Stolz classification. Excellent outcomes were recorded in 100% of type 3, 77.7% of type 4a, and 75% of type 4b cases. Documented complications included one case of radioulnar synostosis and two cases of heterotopic ossification. Conclusions: The Metaizeau technique represents an efficacious treatment option for pediatric radial neck fractures, offering favorable long-term functional and radiological outcomes with a low complication rate. Long-term follow-up data further support the reliability of this technique. Types of Studies: Level IV.

Modified double-row suture bridge technique for anterior colliculus fractures combined with deltoid ligament injury: a retrospective study

BackgroundThe management of anterior colliculus fractures in combination with deltoid ligament injuries is a topic of debate, and there is a need to improve surgical outcomes. The purpose of the present study was to describe the application of a modified double-row suture bridge technique and evaluate its early clinical outcomes in the management of anterior colliculus fracture combined with deltoid ligament injury.MethodsFrom 2020 to 2022, 12 patients with anterior colliculus fracture combined with deltoid ligament injury were treated using a modified double-row suture bridge technique. For clinical outcome evaluation, objective data are presented through clinical examination findings; radiographic assessments, including X-rays and computed tomography (CT); and follow-up analysis utilizing American Orthopaedic Foot & Ankle Society ankle‒hindfoot (AOFAS) scores, Olerud Molander Ankle Scores (OMAS), and visual analogue scale (VAS) scores. Preoperative and follow-up scores were compared with Student’s t test. (p < .05).ResultsThe mean age of the patients was 52.67 ± 9.42 years (range: 39–74). The mean duration of follow-up was 14.42 ± 1.51 months (range: 12–17). At the final follow-up, the mean AOFAS score (P < 0.001) improved to 91.50 ± 2.65 points (range: 87–96), the mean OMAS (P < 0.001) improved to 77.08 ± 3.97 points (range: 70–85), and the mean VAS score (P < 0.001) improved to 0.25 ± 0.45 points (range: 0–1). Nine patients achieved excellent outcomes, and three achieved good outcomes according to the AOFAS score. Follow-up imaging evaluation indicated satisfactory alignment of the fracture and complete healing. Clinical examination suggested good mobility of the ankle. At the last follow-up, ankle dorsiflexion mobility was 14–18 degrees, plantar flexion mobility was 42–45 degrees, inversion mobility was 27–32 degrees, and eversion mobility was 22–25 degrees.ConclusionsThe modified double-row suture bridge technique is effective for achieving anatomic reduction of anterior colliculus fractures, and the technique also provides substantial benefit to the injured deltoid ligament. With this technique, the clinical outcomes can be significant and encouraging, indicating a new stage in its application and development.

3D imaging techniques for the diagnosis and surgical planning of complex limb fractures: a systematic review

This systematic study will investigate how 3D imaging techniques have improved diagnosis and planning of surgeries for complex limb fractures. These fractures are caused of high-energy trauma which presents unique challenges, so advanced imaging technologies can help to mitigate them. We strictly adhere PRISMA guidelines to ensure thorough analysis and inclusion of relevant literature. The search was conducted on Web of Science and PubMed were all thoroughly searched between 2010 and 2023. Keyword combinations such as "3D imaging," "complex limb fractures," and "surgical planning" were employed using Boolean operators and as a result, 26 studies were included following screening based on strict inclusion criteria. 56% of studies used CT scans, demonstrating a 32% increase in diagnosis accuracy over 2D techniques for complicated fractures. In 28% of cases MRI improved soft tissue evaluation. 3D printing was utilized in 16% of investigations and it improved postoperative alignment in 94% of cases and shortened operating times by 18%. We can conclude that 3D imaging greatly enhances surgical planning, patient outcomes, and diagnostic precision in complex limb fractures and it provides useful resources for surgeons and patients by improving fracture visualization, reducing operating time, and promoting quicker recovery.

Experimental investigation on fracture propagation in shale fractured by high-temperature carbon dioxide

The productivity of shale reservoirs was significantly enhanced by the high-temperature CO2 fracturing technique. The injection of high-temperature CO2 into the formation induced rock fracture propagation, creating advantageous pathways for fluid flow. In this research, a self-developed in situ high-temperature convective heat simulation experimental apparatus was employed to systematically conduct simulated experiments on high-temperature CO2 fractured shale under different influencing factors. The experimental results demonstrated that the permeability of CO2 increased as the injection temperature increased. The rock fracture pressure was effectively reduced by high-temperature CO2 fractured shale. Higher complexity was observed in fracture propagation, accompanied by a substantial increase in microcracks and branching fractures. The shale fracture pressure increased with increasing triaxial stress and CO2 injection rate. The confining pressure restricted the further propagation of fractures under relatively high stress conditions, thereby reducing the width and density of fractures, lowering the fracture complexity. Nevertheless, the thermal shock effect of the fluid was exacerbated as the injection rate of high-temperature CO2 increased. The initiation of microcracks was facilitated by the intensification of local thermal stress in shale, inducing multiple curved fractures and forming a more complex fracture network. Compared to horizontal bedding shale, the fracture pressure of vertical bedding shale was relatively higher during high-temperature CO2 fracturing. In addition, the geometric morphology of fracture propagation was more complex, characterized by rougher fracture surfaces, leading to a greater improvement in reservoir reconstruction volume. This research contributed to the optimization of CO2 resource utilization, provided experimental evidence for the application of high-temperature convection fracturing technology in in situ shale conversion projects.

Clinical outcomes of retrograde intramedullary multiple pinning for proximal humeral fractures using a modified palm tree technique

BackgroundRetrograde intramedullary multiple pinning using a modified palm tree technique for proximal humeral fractures has attracted interest from surgeons because of its minimal invasiveness into the soft tissue around the shoulder joints. We aimed to evaluate the clinical and radiological outcomes of this procedure. MethodsThis retrospective study included 21 patients who underwent surgery using a modified palm tree technique for proximal humeral fractures between March 2010 and March 2022. Patients with two- and three-part proximal humeral fractures that could be reduced by closed manipulation under general anesthesia were included in this study. All patients were clinically evaluated using the Japanese Orthopaedic Association (JOA) and University of California at Los Angeles (UCLA) shoulder scores. Postoperative radiographic findings, including fracture healing and signs of pinning-related complications, were evaluated. ResultsTwenty-one shoulders in 21 patients (9 men and 12 women) with mean age at surgery of 66.3 ± 19.3 years were evaluated. The mean period until bone union was 2.6 ± 0.7 months. The mean JOA and UCLA shoulder scores at the final follow-up were 84.8 ± 12.1 and 27.5 ± 5.4, respectively. Perforation of the humeral head by Kirschner (K) wires was observed in 9 of the 21 (42.9 %) shoulders. The JOA and UCLA shoulder scores at the final follow-up were not significantly different between the groups with and without perforations (p = 0.41 and 0.27, respectively). The oblique or Y-view detected significantly more wires with perforation of the humeral head than did the anteroposterior view (6 vs. 15 wires, p < 0.01). ConclusionsThe modified palm tree technique for proximal humeral fractures demonstrated good postoperative clinical outcomes and early fracture healing. However, modifications in postoperative management and surgical techniques should be considered to reduce the high rate of perforation of the humeral head by K-wires.

Traumatic Hallux Fracture

The authors present a case of a traumatic hallux (big toe) fracture in a 77-year-old male who was walking near a construction site when a brick fell and hit his big toe on his right foot. This case report highlights the usage of different treatment types in a toe fracture and different techniques used to diagnose the fracture. Treatment options are evaluated based on the location and severity of the fracture.

Analytical and descriptive study of the production behavior for pilot multi-stages hydraulic fracturing wells in southeast Iraq

The hydraulic fracturing technique is a widely used technique worldwide, making it interesting to study. This technique was applied for the first time in Iraq on a tight carbonate reservoir in the Halfaya oil field. In this field, the oil production rates, and flowing pressure were low during production periods reflecting a problem for the development plan designed to increase production using a hydraulic fracture technique. Initially, the hydraulic fracture well showed high oil-producing rates, but then, quickly experienced a high decline failing to keep a stable production rate. To address this problem, it is important to describe and analyze the behavior of pilot hydraulic fracturing wells during their production period, study the inflow performance relationship (IPR), and determine the optimum wellhead pressure above the bubble point pressure (Pb) to avoid loss of lifting energy. Furthermore, it identifies the allowable flow rate to keep stable production, investigates the effect of selecting internal tubing size, and reveals a future production procedure for hydraulic fracture wells. This study reveals that the transient inflow performance relationship observed in the production history of hydraulic fracture well in the tight carbonate reservoir and traditional inflow performance relationship concepts are not applicable. The optimum wellhead pressure for stability in production for Wells w-5 and w-55 is determined to be 750 and 580 psi with optimum rates of 800 and 450 Bbl/D, respectively. The results also showed that producing at a high flow rate may cause a depletion in the fracture potential storage without giving an opportunity for a reservoir to compensate for the produced fluid into fracturing potential storage. The internal tubing size has a passive effect on the hydraulic fracture well, as an increase in size causes an unstable flow zone. Lastly, future production procedures emphasize keeping wellhead pressures stable or increasing them if they drop. This can be accomplished by re-adjusting the choke size according to any changes observed.

Short-term interactions between Longmaxi shale and carbon dioxide-based fracturing fluids

The shale is a dense quarried rock material containing abundant shale oil/gas. Extracting shale gas usually requires fracturing the rock formation to speed up gas desorption and migration. Supercritical carbon dioxide fracturing, as an environmentally friendly and waterless fracturing technique of reservoir stimulation, gains increasing recognition in commercial exploitation of shale oil and gas. However, there is insufficient understanding on the interaction between carbon dioxide-based fracturing fluids and shale, as well as its influence on the mechanical parameters of shale, which are pivotal for determining injection parameters and forming the fracture network. This study focuses on the injection of carbon dioxide-based fracturing fluids to enhance shale gas extraction and carbon dioxide sequestration. Simulation tests of injection were conducted to investigate the influence of different fracturing fluids (deionized water, gaseous/supercritical carbon dioxide, gaseous/supercritical carbon dioxide mixed with brine) injected into shale reservoirs on the microstructure and mechanical properties of shale after short-term physicochemical interaction. This article adopts research methods such as uniaxial compression and uniaxial tensile mechanical experiments based on acoustic emission monitoring and various physical characterizations such as scanning electron microscopy, X-ray diffraction, X-ray fluorescence spectrometer, etc. Results show that following treatment with different carbon dioxide-based fluids, the uniaxial tensile/compressive strength, elastic modulus, fractal dimension of pore structure, and the brittleness index of shale exhibit varying degrees of decrease compared to those of dry untreated shale samples. After interacting with different carbon dioxide-based fracturing fluids, the mechanical parameters and brittleness index of shale decrease more significantly than that of the others as the addition of brine. This study shows that the water in carbon dioxide-based fracturing fluids is a controlling factor affecting the elastic modulus of shale. Additionally, the ductility of the shale increases and the acoustic emission emitting lag due to the coupling effects of brine and carbon dioxide. The change law of the elemental and mineral composition of the shale is consistent with the mechanical strength; and the change of element content and mineral composition is the most significant. Compared to gaseous carbon dioxide, the supercritical carbon dioxide has a greater impact on mineral composition of the shale. The change of mechanical strength and microstructure evolution mechanism caused by the short-term interactions between the shale and fracturing fluids provide theoretical references and implications for the determination of injection parameters and permeability transformation of the Longmaxi shale reservoirs.

Type 4 Tibial Tuberosity Avulsion Fractures: Surgical Treatment Early Outcomes and a Presentation of the Distal Cortical Fixation.

Background: The most published surgical technique for fixating Type 4 (Salter-Harris II) tibial tubercle avulsion fractures is uni-cortical in nature, and stability is suboptimal. This study presents a technique modification that is consistent with AO principles, by which the screws are aimed distally to purchase the posterior cortex of the distal fragment. This technique is defined as a "Distal Cortical Fixation". This modification has not been studied to date and harbors potential advantages. We aimed to assess the safety and efficacy of surgical fixation techniques for the above-mentioned fractures and to describe the new modification. Methods: A retrospective review was conducted at a level 1 children's hospital for surgically treated Salter-Harris II tibial tubercle fractures. Inclusion criteria were patients who sustained Salter-Harris II tibial tubercle avulsion fractures and were documented to reach one of two radiographic endpoints: union (regardless of alignment) or non-union that necessitated additional interventions. Medical records and radiographic studies were analyzed for fracture union and alignment. A comparative analysis was conducted to evaluate outcomes based on different fixation techniques that included Distal Cortical Fixation, a Proximal Screw Technique, and a crossed or multiple screws/pins construct. Results: A total of 37 patients were included with a mean age of 14.8 ± 1.2 years, with 34/37 (91.9%) being male. The most common procedure was a 1 to 3 screw fixation with a Distal Cortical Fixation (n = 21 (56.75%)), followed by a Proximal Screw Technique (n = 8, 21.62%), and a crossed or multiple screws/pins construct (n = 8, 21.62%). There was no difference between the groups in medical history and demographic features. The mean follow-up duration was 35.17 ± 36.79 weeks. There were no non-unions, and only a minimal change in the sagittal and coronal alignment (0.4 ± 1.94 (p = 0.872) and 0.53 ± 3.51 (p = 0.296) degrees, respectively) was noted and was not associated with the surgical technique. Conclusions: The surgical treatment of Salter-Harris II tibial tubercle avulsion fractures, including Distal Cortical Fixation, was presented and was found to provide satisfactory union rates on a short term follow up.

Efficacy of Direct Versus Peripheral Adjuvant Dexamethasone on Duration and Rebound Pain in Regional Anesthesia for Outpatient Distal Radius Fracture Fixation: A Prospective Randomized Controlled Blinded Study.

Despite increasingly wider use, there remains controversy among anesthesiologists regarding preferred formulations and the role of steroid adjuvants in regional anesthesia. There is also uncertainty in the role of dexamethasone when administered directly versus peripherally. We hypothesize that directly mixing dexamethasone into the regional nerve block rather than peripherally administered intravenous dexamethasone will demonstrate a difference in efficacy concerning duration and rebound pain, decreased postoperative pain scores, or opioid consumption within the short-term postoperative period. A prospective, randomized controlled blinded study was conducted for patients undergoing open reduction and internal fixation with a volar plate technique for distal radius fractures. Patients were randomized for their preoperative anesthesia. One group had ultrasound-guided supraclavicular block with ropivacaine with a direct mix of dexamethasone 4 mg (Direct group), while the other group had ultrasound-guided supraclavicular block with ropivacaine and peripheral intravenous dexamethasone 4 mg (Indirect group). Data was collected pre, intra, and postoperatively. Fifty patients consented and participated in the study, with 27 participants in the direct group and 23 participants in the indirect group. Compared to intravenous administration, directly administered dexamethasone demonstrated a significant difference in the average time for the block to fade, onset of motor and sensory recovery, and block resolution. Our findings prove that directly mixing dexamethasone compared to peripherally administered intravenous dexamethasone will demonstrate a difference in efficacy with regards to duration and rebound pain, but do not prove that there will be a difference in decreased postoperative pain scores or opioid consumption within the 24-hour postoperative period. Prognosis Level I.

A study on the impact of ultrasonic-stimulated clean fracturing fluid on the pore structure of medium to high rank coal

The pore structure of coal plays a key role in the effectiveness of gas extraction. Conventional hydraulic fracturing techniques have limited success in modifying the pore structure using clean fracturing fluid (CFF), and the stimulating effects of ultrasonic can enhance the effectiveness of CFF in modifying coal pore structures. To research the effects of ultrasonic stimulation on the pore structure of medium to high-rank coal when using CFF, this study employed mercury intrusion porosimetry (MIP) and low-temperature nitrogen adsorption (LT-N2A) methods to analyze the changes in pore structures after cooperative modification. The results indicate that the pore volume and surface area of medium to high rank coal exhibit an increase and followed by a decrease with increasing Ro,max values, while the average pore diameter and permeability demonstrate a decrease and followed by an increase with Ro,max. Although there are some variations in the results of MIP and LT-N2A analysis for different pore size ranges, the overall findings suggest that ultrasonic stimulation in conjunction with CFF effectively alters the coal pore structure. The most significant improvement was observed in coking coal, where pore volume increased by 22%, pore area decreased by 11% and tortuosity decreased by 47%. The improvement of lean coal is the smallest, the pore volume increases by about 7%, and the surface area decreases by about 14%. It is found that the modification of coal pore volume is mainly concentrated in transition pores and macropores. These research outcomes provide valuable insights into the application of ultrasonic technology in coalbed gas extraction.

Evaluation of the Suture Pull-Out Technique in Anterior Cruciate Ligament Avulsion Fractures at Different Weeks Post-fracture.

Background Anterior cruciate ligament (ACL) avulsion fractures often necessitate surgical intervention, with various fixation techniques available. Among these, the arthroscopic suture pull-out technique has gained attention as a promising approach. However, the influence of surgical timing on patient outcomes remains insufficiently studied. This study aims to evaluate the efficacy of the arthroscopic suture pull-out technique for ACL tibial avulsion fractures and assess how the timing of surgical intervention affects functional outcomes. Methodology This study was conducted at our hospital from November 2020 to October 2022. A total of 17 patients aged 21 to 41 years with isolated ACL avulsion fractures and no additional injuries or osteoarthritis were included. Participants were divided into three groups based on the interval from injury to surgery (one, two, or three weeks). The surgical procedure involved the suture pull-out technique. Postoperative management included immobilization, isometric exercises, and gradual weight-bearing. Functional outcomes were assessed using the Lysholm score, International Knee Documentation Committee (IKDC) score, Tegner Activity Scale, and Lachman test at 6, 10, and 14 months, along with radiological evaluations. Results Significant functional improvements were observed in all groups, with postoperative Lysholm, IKDC, and Tegner scores showing notable enhancements compared to preoperative values. No significant differences were found among the groups regarding the timing of surgery, indicating that delays within the first three weeks did not adversely impact outcomes. Most patients achieved a full range of motion. Two minor postoperative complications were reported, namely, one case of arthrofibrosis and one case of persistent laxity. Conclusions The arthroscopic suture pull-out technique is effective and reliable for ACL tibial avulsion fixation. The timing of surgery within the first three weeks does not significantly affect functional outcomes. Future research with larger sample sizes and longer follow-ups is recommended to further validate these findings and optimize surgical strategies.

Research and Application of Temporary Blocking and Diversion Techniques for Fractures in Tight Oil Reservoirs

Research and Application of Temporary Blocking and Diversion Techniques for Fractures in Tight Oil Reservoirs

Study on dynamic imbibition mechanism of matrix-fracture in three dimensions tight sandstone based on level set method

Tight oil reservoirs require fracturing techniques to create complex fracture networks for efficient development. It is frequently accompanied by a dynamic matrix-fracture imbibition process, promoting enhanced recovery. At present, the mechanism of three dimensions (3D) matrix-fracture dynamic imbibition at the pore scale has not been fully elucidated. In this paper, the dynamic imbibition process of oil-water two phases in matrix-fracture was simulated based on the Navier–Stokes equations, and the level set method was used to capture the real-time interfacial changes between the two phases. It was found that during matrix-fracture dynamic imbibition process, oil-phase droplets in a single pore remain in the pore mainly due to the “stuck” effect. Cluster residual oil in the pore space is mainly retained due to the “flow around” effect. Continuous residual oil in the deeper regions of the matrix is due to insufficient capillary force. Water phase in the micro-confinement space of a tight reservoir intrudes into the pore space along the pore corners, forming the “fingering” phenomenon is beneficial for enhancing the efficiency of micro-dynamic imbibition. It differs from cognition obtained in the micro-view space during conventional water flooding. The enhancement of imbibition efficiency is often accompanied by the occurrence of fluctuations in the average pressure within the matrix. Therefore, a method involving impulse type of high-frequency and short-period for supplemental energy and imbibition is suggested to enhance recovery in tight sandstone reservoirs. This study reveals the detailed mechanisms of oil-water two-phase transport at different stages in the dynamic imbibition process and holds significant guiding implications for enhancing recovery in this type of reservoirs.

Assessment of Diagnosis of Apical Root Fractures During Tooth Extraction Using Different Radiographic Techniques: An Ex-vivo Study

Objective: This study aimed to examine the diagnostic ability of different imaging techniques for apical root fractures that occur during tooth extraction by specialist dentists in different branches. Methods: Dry human mandibles used for education at Faculty of Dentistry and teeth extracted for routine treatment were used. After the root lengths were measured using a periodontal probe, the samples were adjusted to different lengths. These specimens were placed on a dry human mandible, and images were obtained and recorded using a periapical device, panoramic device, and computed tomography. Radiographs and recordings were performed by an oral and maxillofacial radiologist. The evaluation process was performed by an oral and maxillofacial radiologist, periodontologist, and oral and maxillofacial surgeon. Results: The diagnosis of 1 mm root presence and absence on periapical radiographs showed significant agreement among all observers. In the presence of 2 mm and 3 mm roots, all observers stated that the roots were present. On the panoramic radiographs, moderate agreement was observed in teeth with a 1 mm root. However, poor agreement between observers was observed for teeth with 2 mm and 3 mm roots. Cone-beam computed tomography (CBCT) was effective for the diagnosis of all observers. Conclusion: Consistent with the literature, the present study showed a higher interobserver agreement in CBCT. However, considering the patient's anxiety during the procedure, the duration of local anesthesia, and the surgeon's fatigue, two-dimensional radiographs are generally preferred over CBCT, which has a longer image processing time. Diagnosis using periapical radiographs was more effective than that using panoramic radiographs.

Quantitative Study on the Anticollapse Ability of Casing in Shale Gas Wells under Complex Load Conditions.

Implementing novel technologies, including the "well factory" model and zipper fracturing techniques, has become prevalent in shale gas development. During completion operations such as lowering casing and multistage fracturing, the casing is subjected to many complex loads, reducing its strength and increasing the risk of casing deformation. By establishing a casing wear model and conducting multistage cyclic loading experiments and numerical simulations, we analyzed the change rule of casing anticollapse strength under complex loads, developed a calculation method for casing comprehensive anticollapse ability under complex loads, and applied the method to an illustrative calculation. The study shows that the wear effect during completion has a negligible impact on the strength of the casing. The casing anticollapse strength exhibits a linear decline in correlation with the number of cycles. The zipper fracturing operation resulted in a nonuniform distribution of geo-stress around the well, and the casing anticollapse strength demonstrated a nearly linear decline in correlation with the nonuniformity of geo-stress. In the presence of both internal and external effects, the casing anticollapse strength exhibited a decline exceeding 15%, thereby increasing the risk of casing deformation. This research method can provide computational guidance for preventing casing deformation in field fracturing construction.

Surgical access route and choice of implant in the region of the clavicle shaft

Clavicle fractures are among the most frequent injuries of the shoulder girdle. Nondisplaced fractures are generally treated conservatively, whereas dislocated fractures require surgical reduction and stabilization. A variety of implants and surgical techniques with reliable results are available. While all techniques provide similar healing rates, they share acommon disadvantage with the high incidence of implant irritation and correspondingly high rates of second interventions for material removal. The various surgical techniques for clavicle shaft fractures with their specific areas of application as well as advantages and disadvantages are presented. This review also provides an aid for deciding which surgical technique is most appropriate based on the fracture morphology. Furthermore, an overview of current research activities is presented, with aspecific focus on new implants which could help to reduce implant irritation. Open superior and anteroinferior plate osteosyntheses each show similar reliable results. The minimally invasive plate osteosynthesis (MIPO) technique offers an alternative for multifragmented fractures as it has alower complication rate compared to the open procedure. Double plate osteosynthesis using minifragment plates shows promising results with respect to the incidence of implant-related irritation. Larger prospective studies are still pending. Intramedullary nailing offers agood alternative, especially if material removal is planned anyway, e.g., in the pediatric setting.

Permeability evolution of granite under cyclic hydraulic fracturing and its deterioration during in-situ stress retention in geothermal engineering

Hot Dry Rock (HDR) geothermal resources are a promising source of renewable energy with significant exploitation potential. HDR is typically exist at depths exceeding 2500 m, which presents challenges in terms of high in-situ stress and low permeability of the rock. To overcome these challenges and reduce the risk of fracking induced earthquakes, a scheme for cycling fluid injection has been proposed. In addition, the influence of geo-stress on the re-closure of rock fractures, as well as its effect on granite permeability, are important considerations in HDR exploitation. To study this, the GCTS triaxial testing system has been modified to simulate the hydraulic fracturing process of the deep hot rock reservoir, and permeability tests were conducted simultaneously. A protocol-cyclic fluid injection has been applied to fracture granite specimens under various fluid pressures. The results of the experiments showed that the permeability of the rock was significantly improved after fracturing, with an increase of 1–2 orders of magnitude compared to before. Cyclic hydraulic fracturing techniques can significantly reduce the granite breakthrough pressure and create more complex fracture networks. The permeability of the specimens displayed a decreasing trend during stress retention and tended to stabilize at around 1000 min. The maximum decrease was 90 %, which highlights the importance of considering the impact of stress aging on permeability in engineering. Additionally, the axial and radial strains of the specimens also decreased during stress retention. The mechanism for the change in rock permeability was attributed to the closure of newly formed fractures from hydraulic fracturing. Moreover, the experiments also showed that the smaller the injection fluid pressure, the faster the permeability of the specimens stabilized after fracturing. These findings can provide a theoretical basis for the effect of stress aging on granite permeability and offer reference for secondary fracturing time intervals in practical engineering applications.

Investigation into the Variation Law of Network Fracture Conductivity in Unconventional Oil and Gas Reservoirs

The network fracturing technique is a key technology for increasing effective reservoir volume and enhancing production in shale oil and gas. The fracture network’s conductivity is one of the crucial factors affecting the efficient development of shale gas. To evaluate the variation patterns and influencing factors of the conductivity of network fractures, this study employed a proppant conductivity evaluation system and an equivalent theory testing method. It investigated the conductivity of propped and self-propped fractures under different angles and numbers of fractures. Experimental results showed that fractures with proppant support had higher conductivity than unsupported fractures. Smaller angles between secondary and main fractures resulted in greater conductivity. The conductivity of multi-fracture structures increased with the number of fractures. Under low-closure pressure conditions, self-propped fractures exhibited significantly higher conductivity than propped fractures, but this trend reversed under high closure pressure. This experimental research provides guidance for constructing network fractures with high conductivity in unconventional oil and gas reservoir fracturing.