A Semi-Analytical Geomechanical Approach for Forecasting Production Performance in Multifractured Composite Systems

Stress-dependence of reservoir matrix and fractures can strongly affect the performance of multifractured horizontal wells (MFHWs) completed in unconventional hydrocarbon reservoirs. In order to model fluid flow in unconventional reservoirs exhibiting this stress-dependence, most traditional reservoir flow simulators, and many simulators described in published work, use conventional reservoir fluid flow model formulations. These formulations typically neglect the influence of the rate of change of volumetric strain of the reservoir matrix and fractures, even though reservoir stress and pressure change significantly during the course of production. As a result, the effect of matrix and fracture deformation on production is neglected, which can lead to errors in predicting production performance in most stress-sensitive reservoirs. To address this problem, some studies have proposed the use of porosity and transmissibility multipliers to model stress-sensitive reservoirs. However, in order to apply this approach, multipliers must be estimated from laboratory experiments, or used as a history-match parameter, possibly resulting in large errors in well performance predictions. Alternatively, fully-coupled, fully numerical geomechanical simulation can be performed, but these methods are computationally costly, and models are difficult to setup. This paper presents a new fully-coupled, two-way analytical modeling approach that can be used to simulate fluid flow in stress-sensitive unconventional reservoirs produced through MFHWs. The model couples poroelastic geomechanics theory with fluid flow formulations. The two-way coupled fluid flow-geomechanical analytical model is applied simultaneously to both the matrix and fracture regions. In the proposed algorithm, a porosity-compressibility coupling parameter for the two physical models is setup to update the stress- and pressure-dependent fracture/matrix properties iteratively, which are later used as input data for the fracture-matrix reservoir fluid flow model at each iteration step. The analytical approach developed for the fully-coupled, two-way analytical model, using the enhanced fracture region conceptual model, is validated by comparing the results with numerical simulation. Predictions using the fully-coupled enhanced fracture region model are then compared with the same enhanced fracture region model but with the conventional pressure-dependent modeling approach implemented. A sensitivity study performed by comparing the new fully-coupled model predictions with and without geomechanics effects accounted for reveals that, without geomechanics effects, production performance in stress-sensitive reservoirs might be overestimated. The study also demonstrates that use of the conventional stress-dependent modeling approach may cause production performance to be underestimated. Therefore, the proposed fully-coupled, two-way analytical model can be useful for practical engineering purposes.

Fatigue Failure Analysis of a Speed Reduction Shaft

The mining industry sector is notable for the severe service loads and varied environmental conditions that it imposes on its equipment and mechanical systems. It has become essential to identify the causes of failures and use the information to avoid similar failures and improve projects. In this paper, a study on shaft failure in a speed reduction box was carried out. A section of a fractured shaft made of hardened austempered steel was analyzed to determine the cause of the break. Fractography was performed to characterize the failure mode on the fracture surface. The microstructural analysis and hardness profile revealed that the shaft was inadequately heat treated, resulting in low resistance microstructures and the development of a thin layer of bainite at the shaft edge. Large amounts of inclusions were found in the fracture region, and the tensile tests revealed that the material had an elongation below the specification. The analyses showed that the combination of factors of a large amount of inclusions present in the low resistance banded structure, and the presence of concentrated pores in that same region, acted in a synergistic way to decrease the fatigue resistance and fatigue life of the shaft material.

Forensic Application of Monoclonal Anti-Human Glycophorin A Antibody in Samples from Decomposed Bodies to Establish Vitality of the Injuries. A Preliminary Experimental Study

Glycophorins are an important group of red blood cell (RBC) transmembrane proteins. Monoclonal antibodies against GPA are employed in immunohistochemical staining during post-mortem examination: Through this method, it is possible to point out the RBC presence in tissues. This experimental study aims to investigate anti-GPA immunohistochemical staining in order to evaluate the vitality of the lesion from corpses in different decomposition state. Six cases were selected, analyzing autopsies’ documentation performed by the Institute of Legal Medicine of Rome in 2010–2018: four samples of fractured bones and three samples of soft tissues. For the control case, the fracture region of the femur was sampled. The results of the present study confirm the preliminary results of other studies, remarking the importance of the GPA immunohistochemical staining to highlight signs of survival. Moreover, this study suggests that the use of this technique should be routinely applied in cases of corpses with advanced putrefaction phenomena, even when the radiological investigation is performed, the macroscopic investigation is inconclusive, the H&E staining is not reliable. This experimental application demonstrated that the use of monoclonal antibody anti-human GPA on bone fractures and soft tissues could be important to verify whether the lesion is vital or not.

Novel Micromotion-Balancing Drilling Technology to Increase Proximal Cortical Strain

Background: We aimed to design a micromotion-balancing drilling system on the basis of the existing locking plate to maintain the balance of the micromotion of the cortex on both sides of a fracture region. We tested the system by subjecting it to a few biomechanical tests.Methods: According to the shape of screw holes on the cortex, the fixed fracture models were divided into a control group (standard screw hole group X126, 6 cases) and an experimental group (elliptical screw hole group N, 36 cases). The experimental group was further divided into 6 subgroups with 6 cases in each (N126, N136, N1256, N1356, N12356, N123456) on the basis of the number and distribution of the screws on the proximal fracture segment. The control, N126, and N136 groups were subjected to 500-N axial load, and other groups were subjected to 1000-N axial load. The displacements of the kinetic head, distal cortex, and proximal cortex were measured. The integral structural stiffness of the model and the proximal cortical strain were calculated. The data of each group were analyzed by paired t-tests.Results: When the distal cortical strains were 2%, 5%, and 10%, the proximal cortical strains in group N126 were 0.96%, 2.35% and 4.62%, respectively, which were significantly higher than those in the control group (X126) (p<0.05). When the distal cortical strains were 2%, 5% and 10%, the proximal cortical strain in group N126 was significantly higher than that in group N136 (p<0.05). However, there was no significant difference between the proximal cortical strains in the two groups with 4 screws (p>0.05). The proximal cortical strain in the 3-screw groups was significantly higher than that in the 4-screw groups (p<0.05), and there was no significant difference in the proximal cortical strain in the 4-, 5-, and 6-screw groups (p>0.05).Conclusions: The new drill and the matching sleeves enabled a conventional locking compression plate to be transformed into an internal fixation system and improved the balanced motion of the distal and proximal cortices. Thus, the strain on a fracture site can be controlled by adjusting the drill diameter and sleeve eccentricity.

Intramedullary Nail Fixation with Autologous Bone Marrow Transplantation in an Incomplete Atypical Femoral Fracture Patient: Use of Bone Marrow Extracted from the Hollow Reamer

The present report describes an incomplete atypical femoral fracture (AFF) patient who underwent simultaneous autogenous bone transplantation to the resected fracture region during intramedullary nail fixation. A 73-year-old female with a history of multiple myeloma had been undergoing treatment with intravenous drip injections of Zoledronic Acid. She was introduced to our department due to the left lateral thigh pain, with no trauma incidence. An anteroposterior radiograph showed a transverse thin fracture line with localized periosteal and endosteal thickening, which is compatible with subtrochanteric incomplete AFF. A biochemical investigation revealed the existence of severely suppressed bone turnover. She underwent intramedullary nail fixation for fear of a complete fracture. After the fixation, the cortical bone at the fracture region was excised as a wedge-shaped block, and bone marrow extracted from the hollow reamer was simultaneously transplanted to the resected fracture region. Histological examination showed few bone formation features at the fracture line in the excised lateral cortical bone. At 7 months after surgery, radiographs demonstrated complete bone repair, and no clinical problems were observed two years postoperatively. To the best of our knowledge, this is the first report in which autogenous bone marrow transplantation, noninvasive to the iliac crest, was performed in an incomplete AFF patient. We believe that this low invasive procedure can be a useful technique for AFF treatment.

In Situ Investigation of Interphase and Microstructure Effects on the Chemo-Mechanics of Thiophosphate Solid Electrolytes

<p>Lithium thiophosphates (Li3PS4, LPS) are promising solid electrolytes for safe, energy dense solid-state batteries. However, chemo-mechanical transformations within the bulk solid electrolyte and at solidjsolid interfaces can lead to lithium filament formation and fracture-induced failure. The interdependent role of kinetically stable interphases and electrolyte microstructures on the onset and propagation of fracture is not clearly understood. Here, we investigate the effect of interphase chemistry and microstructure on the chemo-mechanical performance of LPS electrolytes. Kinetically metastable interphases are engineered with iodine doping and microstructural control is achieved using milling and annealing processing techniques. In situ transmission electron microscopy reveals how iodine diffuses to the interphase and upon electrochemical cycling pores are formed in the interphase region. Pores/voids formed in the interphase are chemo-mechanically driven via directed ion transport. In situ synchrotron tomography reveals that interphase pore formation drives edge fracture events which are the origin of through-plane fracture failure. Active Li metal has a tendency to fill the fracture region. Cycling lithium in fracture sites leads to localized stress within the solid electrolyte which accumulates and ultimately leads to catastrophic failure. Fractures in thiophosphate electrolytes actively grow toward regions of higher porosity and are impacted by heterogenity in solid electrolyte microstructure (e.g. porosity factor).</p>

In Situ Investigation of Interphase and Microstructure Effects on the Chemo-Mechanics of Thiophosphate Solid Electrolytes

<p>Lithium thiophosphates (Li3PS4, LPS) are promising solid electrolytes for safe, energy dense solid-state batteries. However, chemo-mechanical transformations within the bulk solid electrolyte and at solidjsolid interfaces can lead to lithium filament formation and fracture-induced failure. The interdependent role of kinetically stable interphases and electrolyte microstructures on the onset and propagation of fracture is not clearly understood. Here, we investigate the effect of interphase chemistry and microstructure on the chemo-mechanical performance of LPS electrolytes. Kinetically metastable interphases are engineered with iodine doping and microstructural control is achieved using milling and annealing processing techniques. In situ transmission electron microscopy reveals how iodine diffuses to the interphase and upon electrochemical cycling pores are formed in the interphase region. Pores/voids formed in the interphase are chemo-mechanically driven via directed ion transport. In situ synchrotron tomography reveals that interphase pore formation drives edge fracture events which are the origin of through-plane fracture failure. Active Li metal has a tendency to fill the fracture region. Cycling lithium in fracture sites leads to localized stress within the solid electrolyte which accumulates and ultimately leads to catastrophic failure. Fractures in thiophosphate electrolytes actively grow toward regions of higher porosity and are impacted by heterogenity in solid electrolyte microstructure (e.g. porosity factor).</p>

Idealised simulations of cyclones with robust symmetrically unstable sting jets

Idealised simulations of Shapiro–Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it was possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight into SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide range of sensitivity experiments. The control simulation contains a cyclone that fits the Shapiro–Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities along the airstream, including symmetric instability (SI). The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes. Dry instabilities, generated by vorticity tilting via slantwise frontal motions in the cloud head, exist in similar proportions to moist instabilities at the start of the SJ descent and are then released along the SJ. The observed evolution supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study. Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro–Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution. The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified. In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro–Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics.