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Summary Analytical models have been widely used to study the steam-assisted gravity-drainage (SAGD) process. Existing analytical models for this process either underperform or are limited in their applicability. In this paper, a new analytical model is developed to address these shortcomings. The new model consists of three major components. First, an equation for predicting oil production rate during the plateau stage was developed. This equation allows for permeability anisotropy in the reservoir, which is neglected in the majority of existing analytical models. Second, a novel and concise equation for calculating oil production rate during the decline stage was derived. This equation for the first time provides a general relationship between oil production rate during the decline stage and the properties of the reservoir together with key operating conditions and simultaneously mitigates the shortcomings of the majority of existing models (e.g., inapplicable in the decline stage of the SAGD process). Third, new correlations representing heat loss from the steam chamber to the overburden and heat transfer to oil-undepleted zone ahead of the chamber interface were derived; new predictive equations for estimating steam/oil ratio (SOR) in the plateau and decline stages of SAGD were obtained. The new model has been validated against a 2D scaled laboratory experiment and a set of field data. The results of this validation show that the new model predicts the oil production rate and SOR over the lifetime of an SAGD operation (excluding the short steam rise period) reasonably well. Predictions from the new model were also compared with several existing analytical models: The new model provided a closer match to actual measurements than other models. This robust model is grounded in more physics and incorporates reservoir geology and well operating conditions. It enables better understanding of the SAGD process and significantly improves the prediction of SAGD performance. Hence, it can be used to design new SAGD projects, predict existing projects, and optimize existing projects.

Summary Fluid flow and heat transfer during steam chamber rise (ramp up) in the steam-assisted gravity-drainage (SAGD) process is very complex. The majority of existing analytical models fail to capture the physics of this stage and their estimations of oil production and steam/oil ratio (SOR) may be questionable. This paper presents a new analytical model to predict the advancing velocity of the steam chamber in the vertical direction, correlations of oil production rate and SOR, and the evolution of chamber profile during this stage using material/energy conservation and gravity-drainage theory. The new analytical model was validated against field observations, laboratory measurements, and numerical simulations. Results showed that the new analytical model not only successfully predicted oil production rate and SOR with improved reliability and accuracy but also for the first time properly predicted the chamber profiles with time during the ramp up stage. Using this model, impacts of the key parameters were investigated. The investigation revealed that permeability anisotropy had a considerable impact on development of the chamber profile. Under the constant horizontal permeability condition, the smaller the ratio of vertical to horizontal permeability, the shorter and wider the chamber profile. A small subcool control strategy could boost oil production and steam chamber growth, which is consistent with experiments and field data. Investigation also found that increasing the distance between injector and producer was beneficial for oil production. However, changing this distance may cause some operating/performance/economic problems and so should be approached cautiously. This paper represents the first time that the evolution of chamber profiles in the ramp up stage was characterized mathematically. Useful guidance for operators on improving ramp up performance can be extracted directly from this model.

In recent years, as an important functional material, glass has been widely used in architecture, electronics, optics, and other fields. As an emerging glass processing technology, the glass molding process (GMP) has received widespread attention and research in recent years. In this paper, we study the modeling and analysis of different heat transfer strategies for the energy efficiency of large-sized automotive instrument glass. The heat transfer model of the metal heating plate–conducting plate mold is established, the thermal energy efficiency in the forming process of large automobile glass is analyzed, and the energy efficiency of the mold in the heating stage is compared. The energy consumption per piece generated by the GMP heating device is reduced from 4865.2 to 4668.5 kJ, a reduction of 4.04%. By optimizing the heat flow density, the energy consumption per piece generated by the GMP heating device was reduced from 4865.2 to 4625.5 kJ, a reduction of 4.92%, meeting the sustainable manufacturing requirements.

Heavy oil, with high viscosity and complex compositions, often faces a series of challenges in the process of its exploitation and utilization. There are huge amounts of compositions with different...

Heavy oils are commonly found in China; however, the Karamay heavy oil is unique among all. It has very low asphaltene content and is an excellent feedstock for producing high-quality lubricant bas...

Interbedded shale (IBS) impedes the development of a steam chamber and poses a serious threat to the success of any steam-assisted gravity drainage (SAGD) operation in a heavy-oil reservoir. Breaking up IBS has been a continual challenge for the industry. This study summarizes experimental studies on the geomechanical properties and failure behaviour of IBS during thermal stimulation. IBS cores were collected by means of fully sealed coring in northwestern China. Mineral composition analysis, porosity, and permeability measurement, as well as imbibition tests, were initiated to evaluate the potential of imbibition. First, shear failure behaviour was studied through triaxial compression tests. Second, pore structure and failure processes of IBS were investigated through thermal stimulation experiments. Mudstone IBS was considered as the focus. Its porosity was approximately 7% and permeability was approximately 100 nD while in-situ stress was applied. Although IBS contained considerable smectite components, it didn’t disintegrate under high-effective stress. Last, shear failure behaviour of IBS was observed by computer tomography (CT) scanning when IBS was heated up to 180 °C under constant radial confining pressure and axial constraint of strain. While imbibition causes disintegration of IBS, it is unlikely when under in-situ stress conditions. Fortunately, shear failure can be achieved under uniaxial boundary conditions with rapid heating.

An increasing number of individuals are suffering from lower back and neck pain caused by intervertebral disc degeneration each year. Although the application of mesenchymal stem cells (MSCs) has provided desirable results in the treatment of intervertebral disc degeneration, there are multiple risks associated with the directed application of MSCs. An increasing number of studies have suggested that stem cells, through the release of extracellular nanovesicles, have vital functions in tissue regeneration and repair with low risk. The present study investigated the effect of extracellular nanovesicles derived from adipose-derived stem cells (ADSCs) on nucleus pulposus (NP) cells from patients with intervertebral disc degeneration. Human NP cells were obtained from patients with intervertebral disc degeneration undergoing surgical procedures in addition to ADSCs from liposuction patients. ADSC-derived extracellular nanovesicles were isolated and characterized. The differentiation and biological activity of NP cells cultured with or without ADSC-derived extracellular nanovesicles were assessed and inflammatory factors and intervertebral disc degeneration-associated markers were also measured. The results indicated that extracellular nanovesicles derived from ADSCs increased the migration and proliferation of NP cells and inhibited inflammatory activity, suggesting their utility for the treatment of intervertebral disc degeneration.

Objective To evaluate the efficacy and safety of tranexamic acid (TXA) for single-segment thoracolumbar burst fracture without neurologic injury underwent pedicle screw fixation via Wiltse approach. Patients and methods We identified 264 patients with single-segment thoracolumbar burst fracture without neurologic injury underwent pedicle screw fixation via Wiltse approach (January 2016-June 2019) at a single center. The cohort was separated into three groups. Group A received 20 mg/kg TXA at 5 min before skin incision and 16 h after first dose; Group B received 20 mg/kg TXA at 5 min before skin incision; Group C received NS at each same time point. The outcomes were evaluated by hidden blood loss (HBL), total blood loss (TBL), intraoperative blood loss (IBL), transfusion rate, maximum hemoglobin (Hb) drop, prethrombotic state molecular markers, liver and renal function, coagulation function, inflammatory factor and adverse events. Results The HBL, TBL and maximum Hb drop were significantly lower in Group A than those of Group B and Group C, while the difference between Group B and Group C was statistically significant. The IBL was significantly lower in Group A and Group B than that of Group C. However, there was no significantly difference among the three groups in live and renal function, coagulation function, prethrombotic state molecular markers, transfusion rate and complications during the perioperative period. There was significantly lower level of interleukin-6 (IL-6) in Group A than Group C at the day after surgery, and lower level of C-reactive protein (CRP) at the third day after surgery. Conclusions Intravenous TXA used in the treatment of thoracolumbar burst fracture underwent pedicle screw fixation via Wiltse approach is effective and safe in decreasing perioperative blood loss. The two-dose TXA regimen can further reduce blood loss and alleviate post-operative inflammation response, without affecting prethrombotic state molecular marks and without increasing the risk of complications.

Steam distillation can effectively enhance heavy oil recovery during steam injection process in heavy oil reservoirs. However, the mechanism of steam distillation is complex, and the changes in oil properties during distillation remain unclear. In this study, three comparative steam distillation experiments were designed and conducted, including distillation processes employing saturated steam, steam superheated by 10 °C, and steam superheated by 40 °C. Heavy oil samples were derived from the Jin-1 Block in a typical heavy oilfield, in China. The density, viscosity, SARA fractions, and carbon number distribution of the residual oil were compared to those obtained before conducting steam distillation experiments. The steam distillation rates obtained with steam superheated by 40 °C, steam superheated by 10 °C, and saturated steam were 11.158%, 10.903% and 10.423%, respectively. The results indicate that the steam distillation rate of heavy oil increases significantly with increasing degree of superheating. During the steam distillation process, the density and viscosity of residual oil increase, the contents of saturated hydrocarbons and resin decrease, and the contents of aromatic hydrocarbons and asphaltenes increase. In addition, analysis of the distilled components indicates that lightweight components with smaller carbon numbers are removed firstly by steam distillation, followed by heavier components with larger carbon numbers. Moreover, all hydrocarbons with carbon numbers less than C22 are removed from heavy oil in the distillation process, while the maximum carbon number of the distilled components was C34. This study is favorable for understanding the changes in the properties of residual oil after distillation during the steam injection process for heavy oil recovery.

The presence of significant amounts of injected steam and heat loss are unavoidable issues occurred that are observed during the steam-assisted gravity drainage (SAGD) process in developing heavy oil reservoirs. Because of these limitations and concerns, non-condensable gas co-injection has become a potential technique to enhancing oil recovery and reducing energy consumption. However, the oil production mechanism is complicated and has not been totally understood, thereby requiring further discussion. In this work, a two-dimensional physical model was designed to investigate the production mechanisms of nitrogen on SAGD. Two comparative injection schemes, specifically the conventional SAGD and nitrogen assisted SAGD (NA-SAGD), were conducted to investigate the effect of nitrogen co-injection with steam on the SAGD performance. Dynamic temperature profile changes during the two experiment processes were monitored and recorded. The observation results indicate that nitrogen accumulation at the upper part of the model resulted in the effective expansion of the NA-SAGD process steam chamber along the horizontal direction. The swept area of steam increased significantly and the residual oil saturation was reduced. The cumulative oil production of NA-SAGD was higher than that of the conventional SAGD. Moreover, the apparent heat loss reduction, which defines the heat utilization efficiency, exhibited an increase following nitrogen injection. In addition, a numerical simulation was generated to compare and verify the results obtained in the two experiments. Nitrogen co-injection with steam effectively enhanced the oil recovery. Studies indicate that NA-SAGD is a feasible method for improving oil production in developing heavy oil reservoirs.

Liquid crystal display (LCD) is a display device based on liquid crystal electro-optic effect, and LCDs have gradually appeared and have become an indispensable part of people’s lives. In the development of LCD technology, the detection of Mura defects is a key concern in the manufacturing process. The Mura defect is a kind of display defect with low contrast and an irregular shape. This study first explains the mechanism of Mura defects in the LCD manufacturing process and classifies typical Mura defects. Then, three main purposes for the defect detection of LCDs are compared, and the advantages and disadvantages are conducted. Following that, this research examines reviews the linked literature on image preprocessing, feature extraction, dimension reduction, and classifiers of Mura defects. Finally, the future development trend and research direction of Mura defect detection based on machine vision can be drawn by this study.

Non-condensable gas (NCG) co-injection in mature Steam Assisted Gravity Drainage (SAGD) chamber had been widely implemented and significant amount of steam was saved. Encouraged by their performance, NCG SAGD was also tested in Xinjiang oilfield since 2012. Its strategy differed from others in that nitrogen slug was injected once per year since the early SAGD stage. However, its performance was quite mixed. A unique 2D model was used to mimic the field operation of SAGD and NCG SAGD. The general performance, temperature drop, pressure oscillation, gas fingering and gas coning were analyzed. It showed non-condensable feature of NCG lead to gas accumulation and pressure oscillation in NCG slug operation. Its partial pressure effect lowered down temperature, saving steam but reducing oil rate, potentially leading to gas coning issue. The main purge mechanism was gas solubility in water and oil which controlled the NCG concentration inside the steam chamber. NCG fingering was found to speed up vertical growth of steam chamber in the early SAGD stage. However, injecting NCG before chamber getting mature should be treated with caution. Lastly, NCG was recommended to inject through vertical well to the top of the formation.

Effective communication in the well pair during the preheating period has a significant effect on the success of the production period by using steam-assisted gravity drainage (SAGD) technology in heavy oil reservoirs. However, the time-consumption and the economic cost associated with steam generation and circulation limit the application of this technique. Because of these limitations and concerns, we have investigated the effectiveness of the solvent injection-assisted start-up period. A sand-pack physical experiment was designed to evaluate the effect of solvent on heavy oil-viscosity reduction. Different solvents were tested to examine the effects on viscosity reduction and asphaltene precipitation. Xylene was selected as asphaltene-soluble solvent for this experiment. The solvent was injected at different injection rates and diffused into the bitumen during the soaking period. Furthermore, a numerical model was constructed to simulate the performance of the preheating and early production period with or without solvent injection in the start-up process. The observations and simulation results indicate that the injected solvent diffuses to improve the sweep area to further reduce oil viscosity significantly in the soaking time. However, too long soaking time results in lower concentrations of solvent has the opposite effect on oil-viscosity reduction. The relative permeability of the oil phase increases as well. Whereas, according to numerical simulation, the solvent-assisted start-up process of SAGD shortens preheating time and reduces steam consumption. Both the production rate and the cumulative oil production improve during the early production period.

Previous studies have reported that T cell immunoglobulin domain and mucin domain-3 (TIM-3) 574T>G and 1516G>T are associated with the risk of asthma. However, the results are inconsistent due to the small sample size and varied age in studies. We performed this metaanalysis to systematically evaluated the effect of TIM-3 574T>G and 1516G>T genetic polymorphisms on asthma. Eligible articles that reported an association between TIM-3 574T>G and 1516G>T genetic polymorphisms and asthma were searched in PubMed, Medline, EMBASE, Google Scholar, and China National Knowledge Infrastructure up to April 2020. Random or fixed-effects models were used to calculate the summary of odds ratios (ORs) and 95% confidence intervals (CIs) to detect any potential associations between TIM-3 genetic polymorphisms and asthma. Subgroup and sensitivity analyses were performed to assess the potential sources of heterogeneity and the robustness of the pooled estimation. Publication bias was analyzed using the Egger test. A total of 11 case-control studies including 2077 asthma patients and 2122 control subjects were finally analyzed (published data form 2004-2018). The pooled results indicated that TIM-3 574T>G genetic polymorphisms were significantly associated with an increased risk of asthma under the dominant model (GG vs. GT +TT: ORs=2.26, 95% CI 1.09-4.69) and allele model (G vs T: ORs=2.60, 95% CI 1.20-5.64). However, no significant associations between TIM-3 1516G>T genetic polymorphisms with asthma in any model was found. No evidence of publication bias was observed. Our study indicates that TIM-3 574T>G genetic polymorphisms were associated with increased risk of asthma and the TIM-3 1516G>T genetic polymorphisms may not be correlated with asthma.

Laboratory experiments and pilot applications have proved that urea is an efficient agent to enhance heavy oil recovery. Numerous studies have been conducted to investigate the mechanisms of urea co-injection process in steam flooding or cyclic steam stimulation. However, investigations of applying urea in steam assisted gravity drainage (SAGD) process are rarely published. The mechanism of enhanced oil recovery in the urea assisted SAGD process has not been fully understood. Laboratory experiments and numerical simulations were conducted to study the decomposition rate of urea, the effect of urea decomposition products on reservoirs and pipelines, and the distribution of effective decomposition products of urea in the steam chamber at conditions of different concentrations, temperatures, and injection rates. The results show that the solubility of the effective urea decomposition products affects their distribution in the formation because of the huge difference between the solubility in oil and water. In SAGD process, urea cannot be completely decomposed and will produce solid decomposition products, which could block the reservoir pores and production pipelines in certain conditions. Moreover, numerical simulation indicates that the use of low-concentration urea injection in SAGD can effectively enhance oil recovery and oil production rate, while high-concentration urea can reduce the oil recovery and oil production rate. In addition, it was proved that CO2 mainly exists at the edge of the steam chamber and NH3 is distributed in the irreducible water near the well-bore. CO2 is more effective than NH3 for enhancing oil recovery in urea assisted SAGD. Studies indicate that urea co-injection is a feasible method for enhancing oil recovery in the SAGD process.

Physical modeling is critical to study the performance of certain operation in heavy oil reservoirs. A well-designed experiment should guarantee the information gathered from lab would be applied to predict the thermal process in the field. To meet this requirement, the initial and boundary condition similarity between lab and field should be satisfied. It is reasonable to follow certain scaling criteria to fabricate the physical model. In addition to these conventional guidelines, this paper makes following recommendations to ensure a successful thermal recovery experiment,•To control and mitigate the steam channeling between the sand-pack and apparatus wall, the back wall is designed as it can be pushed enough to increase contact pressure.•Heat loss should be handled carefully, which impacting steam chamber growing and causing heat accumulation around the model.•A data acquisition system, based on PXI platform and Labview software, for the thermal recovery experiments had been proved valuable in evaluating the spreading progress of steam chamber., Graphical abstarct Image, graphical abstract

We compared the mid-term efficacy and safety of anterior cervical discectomy and fusion (ACDF) using a Zero-Profile device for cervical degenerative disc disease (CDDD) with and without osteoporosis.We performed a retrospective study of elderly patients with CDDD treated by single-level ACDF with a Zero-Profile device. The patients were divided into group A (osteoporosis) and group B (no osteoporosis) according to the bone mineral density. The clinical outcomes (Japanese Orthopaedic Association, neck disability index, visual analog scale, and short-form 36 scores), radiological outcomes (cervical lordosis and fusion rate), and complications were reviewed at each follow-up examination.All procedures were successfully performed in all patients. The Japanese Orthopaedic Association, neck disability index, visual analog scale, and short-form 36 scores and cervical lordosis were significantly improved postoperatively in both groups (P0.05). However, no significant difference was found between the 2 groups at each follow-up point (P0.05). No significant difference was found in the fusion rate at 3 months postoperatively (group A, 88.9%; group B, 90.0%), dysphagia rate at 1 month postoperatively (group A, 11.1%; group B, 15.0%), or cage subsidence rate at the final follow-up visit (group A, 11.1%; group B, 10.0%; P0.05). All patients achieved solid fusion, and no patient had dysphagia at the final follow-up examination.ACDF with the Zero-Profile device can be used as an effective and reliable treatment for single-level CDDD with osteoporosis.

Results on the relationships between vitamin D receptor (VDR) gene polymorphisms and postmenopausal osteoporosis (PMOP) susceptibility and bone mineral density (BMD) are conflicting. The aim of the study is to identify more eligible studies that calculated pooled OR and WMD with 95% CI to assess their associations. Overall, there were significant correlations between VDR ApaI, VDR FokI and PMOP susceptibility. Subgroup analysis showed that VDR ApaI polymorphism significantly decreased the osteoporosis risk in Caucasian postmenopausal women. In Asian populations, VDR BsmI and VDR FokI were associated with an increased risk of PMOP. As to the associations between VDR polymorphisms and BMD, Caucasian PMOP women carrying the ApaI aa genotype were at risk of high BMD in femoral neck, and low femoral neck BMD was observed in Caucasian PMOP women with FokI Ff genotype. PMOP women with the Cdx2 GA genotype had a lower lumbar spine BMD in overall and Caucasian populations compared with PMOP women with GG genotype. Different VDR gene polymorphisms have different impacts on PMOP risk and BMD.

This is the first systematic review and meta-analysis to detect the incidence and risk factors for postoperative shoulder imbalance (PSI) in scoliosis. A systematic online search was conducted to identify eligible studies. ES, OR and WMD with 95% CI were used to assess the incidence and risk factors associated with PSI. Twenty-six studies were recruited. The pooled incidence of PSI was 25% (95% CI 20–31%). The incidence in Lenke 1 AIS, Lenke 2 AIS, Lenke 5 AIS and mixed AIS was 20% (9–31%), 26% (15–37%), 31% (17–45%) and 27% (19–35%), respectively. Using RSH ≥10 mm as the criterion of PSI, we found that preoperative LC, postoperative RSH, correction rate of MTC at follow-up were primary risk factors for PSI at follow-up. In the analysis of using RSH ≥20 mm as the criterion of PSI, our results showed that Risser sign, postoperative RSH, correction rate of PTC at follow-up, and LC at follow-up were contributing to PSI. Besides, scoliosis patients with PSI were more likely to suffer from adding-on. The pooled incidence of PSI in scoliosis was 25%. Risser sign, preoperative LC, postoperative RSH, correction rate of PTC at follow-up, correction rate of MTC at follow-up, and LC at follow-up were risk factors for PSI in patients with scoliosis. Adding-on might be a compensatory mechanism for PSI. It is recommended that (1) sufficient correction of PTC and moderate correction of MTC and LC in the operation should be performed; (2) PSI should be prevented not only for the patients’ postoperative appearance, but also for preventing the adding-on phenomenon.

For the last decade, the integrity of caprock was the dominant topic in SAGD aspects, especially after Josyln creek steam release accident (ERCB, 2010). Lots of works had been done to identify the failure mechanisms (Carlson, 2012) and massive progress had been made(Collins, Walters et al., 2011; Yuan, Xu et al., 2011; Walters, Wang et al., 2012). One of these efforts was to determine the maximum operating pressure from geomechanical study (Walters, Wang et al., 2012). Another issue in SAGD operation falled into geomechanical category as well was inter-bedded shale (IBS), which largely impeded the vertical growth of SAGD chamber (ITO, T. HIRATA et al., 2004). IBS generally yielded low operation performance in heterogeneous reservoir and gradually draw the attention of the industry and academia. Yang (Yang and Butler, 1992) was the first to conduct physical simulation to study the effect of relative position and size of IBS on SAGD performance. He concluded IBS above the injector would force steam chamber to detour which largely delayed the rising process of chamber. So breaking IBS to facilitate fluid flow has been an objective pursuit by the industry.Actually the efforts to prevent caprock from failure was essentially the reverse purpose of breaking IBS. The conditions leading to caprock integrity issue were exactly those to promote potential failure of IBS. Conventional ideas like drilling slim hole, vertical well, tunnel or fishbone wells (Chang, Ivory et al., 2012; JOHN L. STALDER, 2012; PTAC, 2012; TUNNEY CATHAL, 2012) might sound great but failed to meet the challenge of identifying location of IBS precisely. Alternately in situ method was more feasible and most works reported in public domain fell into this category. As is well known, rock failure happened normally in the forms of shear failure and tensile failure (Carlson, 2003; Collins, 2005; Dusseault and Collins, 2008). Shear failure was especially common in anisotropic stress condition. Accompanying with this concept, uniaxial boundary condition was widely integrated (Walters, Wang et al., 2012). It was rather simple and ideal model. In addition, failure criteria was another important ingredient for shear failure study. Models like Mohr-Coloumb (Carlson, 2003; Collins, 2005; Dusseault and Collins, 2008) and Drucker-Prager (Yuan, Xu et al., 2011; Yang, Xu et al., 2013) were generally used in academic research. The former one was widely used in engineering activities while the latter one was commonly adopted for numerical simulation (IPEK, FRAUENFELD et al., 2008; Du and Wong, 2010). Tensile failure was also possible in certain unloading condition (XU, YUAN et al., 2011) and should be concerned properly. It's necessary to mention Li's work (Li and CHALATURNYK, 2006) in which a relation between permeability and volumetric strain was derived. This essentially bridged the gap between reservoir engineering and geomechanical research and helped understand permeability enhancement after failure.Apart from numerical simulation, physical experiments also provided valuable thoughts to address IBS issue. Collins & Carlson (Carlson, 2003; Collins, Walters et al., 2011) taught proper methods to core, store, and prepare core plugs for experiments. Collins (Collins, 2005) reviewed the work at UTF project and concluded that stress front propagated far ahead of temperature and pressure front. This finding indicated IBS would be broken by means other than fluid injection. One of the most feasible approach was thermal stimulation which was already there in SAGD operation. Heat was one of the most important component in thermal stimulation process and heat transfer always exist in IBS no matter steam or hot water entered. In contrast, fluid wouldn't penetrate IBS with extremely low porosity and permeability and hence alter the stress condition inefficiently. Dr yuan (XU, YUAN et al., 2011) conducted lab tests and showed both shear failure and tensile failure of IBS during thermal loading. He argued that the stress path and loading history was important and might lead to thermal contraction or thermal expansion. Thermal expansion was critical in thermal stimulation process(AGAR, MORGENSTERN et al., 1983; BUTLER, 1986) which might result in pore pressure increase and anisotropic stress status. To which extent this factor might affect the strength of IBS depended on the competition between thermal expansion and pressure dissipation. On the other hand, thermal contraction of shale was also extendedly studied (Bois, CurisTec et al., 2011; Li and Wong, 2013) and fractures would developed in certain condition. Hueckel (Hueckel and Baldi, 1990; Hueckel and Borsetto, 1990) studied saturated clay heating under undrained condition. He presented yield surface change in p'- q - T plot and found overconsolidation ratio played an important role in the failure behavior. Wong (Wong, 1998) proved that swelling caused by water imbibition was an alternative to weaken shale and improve effective permeability.

Osteoporotic vertebral compression fractures with intraosseous vacuum phenomena could cause persistent back pains in patients, even after receiving conservative treatment. The aim of this study was to evaluate the efficacy of using high-viscosity bone cement via bilateral percutaneous vertebroplasty in treating patients who have osteoporotic vertebral compression fractures with intraosseous vacuum phenomena. Twenty osteoporotic vertebral compression fracture patients with intraosseous vacuum phenomena, who received at least 2 months of conservative treatment, were further treated by injecting high-viscosity bone cement via bilateral percutaneous vertebroplasty due to failure of conservative treatment. Treatment efficacy was evaluated by determining the anterior vertebral compression rates, visual analog scale (VAS) scores, and Oswestry disability index (ODI) scores at 1 day before the operation, on the first day of postoperation, at 1-month postoperation, and at 1-year postoperation. Three of 20 patients had asymptomatic bone cement leakage when treated via percutaneous vertebroplasty; however, no serious complications related to these treatments were observed during the 1-year follow-up period. A statistically significant improvement on the anterior vertebral compression rates, VAS scores, and ODI scores were achieved after percutaneous vertebroplasty. However, differences in the anterior vertebral compression rate, VAS score, and ODI score in the different time points during the 1-year follow-up period was not statistically significant (P > 0.05). Within the limitations of this study, the injection of high-viscosity bone cement via bilateral percutaneous vertebroplasty for patients who have osteoporotic vertebral compression fractures with intraosseous vacuum phenomena significantly relieved their back pains and improved their daily life activities shortly after the operation, thereby improving their life quality. In this study, the use of high-viscosity bone cement reduced the leakage rate and contributed to their successful treatment, as observed in patients during the 1-year follow-up period.