Root Cause Analysis of Wells with Integrity Failures

A Root Cause Analysis (RCA) is a methodological process of problem solving. In brief, this is an approach of "post mortem" analysis of the consequences with aim to understand what is one single (or multiple) lack of Management System that led to failure. Subsequently we can develop detailed remedial plan and actions to address failed Management System and most importantly prevent reoccurrence. Approach has been widely used in science and engineering. Probably, will be difficult to identify inventors of this analysis however first appearance in engineering discipline credited to Sakichi Toyoda, founder of Toyota Industries. He improved RCA by implementing technique called the "5 whys". Despite obvious benefit and versatility of root cause analysis methodology there are several challenges that might jeopardize result:–Absence of critical data / information due to various reason (time gap, no recoverable samples etc)–Too many variables that not allow to pinpoint main line / chain of investigation–Multiple failures with different root causes–"Depth of investigation" how many "Whys" are efficient to reveal main root cause.

Virtual Space Vector Pulse Width Modulation for Asymmetric T-Type Neutral Point Clamped 3-Level Inverter

This paper proposes a novel 3-phase asymmetric 3-level T-type NPC inverter and studies its PWM performance using a virtual space vector pulse width modulation control strategy. Firstly, the mathematical model and characteristics of this economical topology are described. Then, a virtual space vector approach is proposed to build a space vector diagram for designing SVPWM control. Similar to the conventional 3-level NPC inverter, the asymmetric inverter can also work with the neutral point voltage self-balancing in a fundamental period, which enables employment of this topology in various applications. Finally, simulation and experiment results under different load conditions have shown good output performance of the asymmetric 3-level topology. Similar tests are also performed on both conventional 2-level and 3-level inverters for comparison. For an almost similar number of different voltage vectors in the space vector diagram, the asymmetric 3-level topology can compete with conventional 3-level inverters for low-cost applications. The obvious benefit of the asymmetric 3-level inverter is a smaller number of switches devices while it can achieve output performance similar to that of the conventional 3-level. The comparative investigation also shows that the total loss given by SVPWM for the asymmetric 3-level configuration is lower than that of the traditional 3-level inverter.

Enhancing Performance of High Viscosity Friction Reducers HVFRs in Brine

High Viscosity Friction Reducers (HVFRs) are often employed in hydraulic fracturing fluids to increase the proppant carrying capacity of slickwater fluids. However, it has been widely reported that the performance of HVFR fluids drops precipitously with even small amounts of salt. This study explores and reports the use of surfactants to alleviate the loss of performance of HVFR fluids due to salinity in the mix water. Fracturing fluids were prepared in the laboratory by mixing the HVFR at concentrations between 2 and 8 gal/1,000 gal with and without surfactant formulations. The viscosities of the fluids were measured on a TA Instruments DHR-3 rheometer using a concentric cylinder geometry. Both anionic and cationic HVFRs were tested with various surfactants. As expected, we observed that HVFR fluids display dramatic loss of viscosity with the addition of as little as 1% salt to the mix water. However, certain surfactant formulations were found to provide a significant boost in viscosity of HVFR fluids in brines over a wide range of shear rates. Increases in viscosity by a factor of as much as 10 times were observed, particularly at low shear rates. The ability of the surfactant formulations to enhance fluid viscosity was observed in both monovalent and divalent model brines, as well as brines that mimicked field produced water compositions. In addition, measurements were also performed in a slot flow device to determine if the results from the rheometer translated to proppant transport characteristics of the fluids. The slot flow results were found to correlate well with fluid viscosity measurements. The fluids containing the surfactant formulation transported nearly 4 times as much proppant as fluids not containing surfactant through a 2.5 ft. long rectangular slot of 0.5 in. thickness at a proppant concentration of 2 lb/gal. An obvious benefit of the approach proposed in this study is that it can enable the use of HVFR fluids in recycled and produced waters, providing both cost and sustainability benefits. Secondly, these surfactant formulations can reduce the amount of HVFR required to obtain a certain target viscosity in brine, thereby reducing the likelihood and potential severity of formation damage from HVFR residue.

Comparing Nonoperative Treatment, MPFL Repair, and MPFL Reconstruction for Patients With Patellar Dislocation: A Systematic Review and Network Meta-analysis

Background: Medial patellofemoral ligament (MPFL) reconstruction, MPFL repair, and nonoperative treatment are important treatments for patients with patellar dislocation. However, it is unclear which treatment leads to better outcomes. Purpose: To determine the efficacy and safety of the 3 treatments in the treatment of patellar dislocation and compare the effect of MPFL reconstruction with MPFL repair, MPFL reconstruction with nonoperative treatment, and MPFL repair with nonoperative treatment. Study Design: Systematic review; Level of evidence, 3. Methods: The PubMed, Web of Science, Cochrane Library, Embase, CNKI (China National Knowledge Infrastructure), and Wanfang databases were searched from inception to December 2020. Included were clinical studies that described the efficacy and safety of 2 of the 3 treatments, studies directly comparing the clinical effects of the 2 operative techniques, or studies comparing the effects of reconstruction or repair with nonoperative treatment. Two reviewers independently extracted data and assessed the quality of the included studies with the Cochrane risk-of-bias tools. The outcomes evaluated were postoperative redislocation rate, revision rate, complications, and Kujala score. We used traditional direct pairwise meta-analysis as well as network meta-analysis for comprehensive efficacy of all 3 treatment measures. Results: Twelve studies were included: 5 compared MPFL reconstruction with MPFL repair, 2 compared MPFL reconstruction with nonoperative treatment, and 5 compared MPFL repair with nonoperative treatment. The risk of bias was serious in 4, moderate in 4 and low in 4 articles. MPFL reconstruction led to significantly reduced redislocation and improved Kujala scores compared with MPFL repair and nonoperative treatment. MPFL repair led to reduced redislocation rates compared with nonoperative treatment but did not show an obvious benefit in primary dislocations. There was no significant difference among the 3 treatments in terms of revision rate and incidence of complications, although we found that treatment-related complications were least likely to occur in nonoperative treatment. Conclusion: The results of this review indicate that MPFL reconstruction decreases recurrent dislocation compared with MPFL repair or nonoperative treatment, but it has a higher possibility of complications. MPFL repair resulted in less postoperative redislocation than nonoperative treatment but did not show an obvious benefit in primary dislocation.

Transverse dural arteriovenous fistula with bilateral sigmoid sinus stenosis treated with via transarterial embolization and venous stent placement: case report

BackgroundDural arteriovenous fistulas (DVAF) is a cerebrovascular disorder due to abnormal connections within meningeal arteries and cerebral veins. It is usually associated with sinus stenosis.Case PresentationWe describe a case of DAVF with bilateral sigmoid sinus stenosis successfully treated via transarterial embolization and unilateral stenting.ConclusionThe author reported a rare case of DAVF associated with with bilateral sigmoid sinus stenosis. Direct embolization with catheterization of contralateral MMA may by an alternative way to treat partial embolized DAVF, when main feeding arteries were occluded due to previous treatment. Unilateral sinus recanalization for bilateral sinus narrows could also obtain obvious benefit.

Effect of Core Architecture on Charpy Impact and Compression Properties of Tufted Sandwich Structural Composites

This study presents a novel sandwich structure that replaces the polypropylene (PP) foam core with a carbon fiber non-woven material in the tufting process and the liquid resin infusion (LRI) process. An experimental investigation was conducted into the flatwise compression properties and Charpy impact resistance of sandwich composites. The obtained results validate an enhancement to the mechanical properties due to the non-woven core and tufting yarns. Compared to samples with a pure foam core and samples without tufting threads, the compressive strength increased by 45% and 86%, respectively. The sample with a non-woven layer and tufting yarns had the highest Charpy absorbed energy (23.85 Kj/m2), which is approximately 66% higher than the samples without a non-woven layer and 90% higher than the samples without tufting yarns. Due to the buckling of the resin cylinders in the Z-direction that occurred in all of the different sandwich samples during the compression test, the classical buckling theory was adopted to analyze the differences between the results. The specific properties of the weight gains are discussed in this paper. The results show that the core layers have a negative effect on impact resistance. Nevertheless, the addition of tufting yarns presents an obvious benefit to all of the specific properties.

Malignant Phyllodes Tumor With Metastases to the Femur the Lung and Bilateral Axillas: A Case Report and Review of Literature

Background: Phyllodes tumor is rare accounting for <1% of all breast tumors. It is classified as benign, borderline, or malignant.The lymph node is involved rarely, and the most common metastasis path is through hematogenous channels mainly to the lung the pleura and the bone. Case presentation: This case report presents a 34-year-old woman suffered from metastases to the femur the lung and bilateral axillas from a malignant phyllodes tumor in 9 years. The most recent recurrence was discovered on bilateral axillas. The patient accepted adjuvant chemotherapy. However, because no obvious benefit of chemotherapy was found, the patient received bilateral axillary lymph node dissection finally. Genetic testing after surgery showed tumor-specific mutations and mutations about thepolymorphism of drug metabolism-related enzymes. Conclusions: The primary treatment modality for phyllodes tumor is surgery. For metastases, adjuvant chemotherapy may be efficient. However, when the effect of chemotherapy is not obvious, aggressive surgical therapies should be performed. Besides, genetic testing can provide advices on effective treatments.

The Impact of the November 2020 English National Lockdown on COVID-19 case counts

In the UK the epidemic of COVID-19 continues to pose a significant threat to public health. On the 14th October the English government introduced a tier system for control of the epidemic but just 3 weeks later a National lockdown across all areas of England was implemented. When English areas emerged from Lockdown many were placed in different tiers (most typically moved up at least one tier). However, the effectiveness of the tier system has been challenged by the emergence of a new variant of SARS-CoV-2 which appears to be much more infectious. In addition, from early November a trial mass testing service was being run in Liverpool. We used publicly available data of daily cases by local authority (local government areas) and estimated the reproductive rate (R value) of the epidemic based on 7-day case numbers compared with the previous 7-day period. There was a clear surge in infections from a few days before to several days after the lockdown was implemented. But this surge was almost exclusively associated with Tier 1 and Tier 2 authorities. In Tier 3 authorities where hospitality venues were only allowed to operate as restaurants there was no such surge. After this initial surge, cases declined in all three tiers with the R value dropping to a mean of about 0.7 independent of tier. London, The South East and East of England Regions saw rising infection rates in the last week or so of lockdown primarily in children of secondary school age. We could find no obvious benefit of the trial mass screening programme in Liverpool city. We conclude that in Tiers 1 and 2 much of the beneficial impact of the national lockdown was lost probably because of the leak of its likely implementation five days early leading to increased socialising in these areas before the start of lockdown. We further conclude that given that the new variant is estimated to have an R value of between 0.39 and 0.93 greater than previous variants, any lockdown as strict as the November one would be insufficient to reverse the increase in infections by itself. The value of city-wide mass testing to control the epidemic remains uncertain.

Ozonetherapy vs SARS-COV-2 in gut: the fountainhead

COVID-19 is the disease caused by the new coronavirus SARS-CoV-2 and is characterized by clinical manifestations ranging from mild, flu-like symptoms, to severe respiratory failure and multi-organ failure. Patients with more severe symptoms may require intensive care treatments and face a high risk of mortality.COVID 19 is characterized by an abnormal inflammatory response similar to a cytokine storm, which is associated with endothelial dysfunction and microvascular complications. To date, no specific treatments are available for COVID-19 and its potentially life-threatening complications.Numerous experimental and clinical observations have suggested that the gut microbiota plays a key role in sepsis and ARDS pathogenesis. The incidence of diarrhea in COVID-19 patients and the high mortality rate in elderly patients, considered together, indicate a possible involvement of the intestine-lung axis in COVID-19 with association of dysbiosis.Ozonetherapy is the administration of a mixture of ozone and oxygen, or Medical Ozone (MO), which produces a series of benefits capable of counteracting a wide range of pathologies, in use for over a century as an unconventional medicine practice.MO is fundamental to inhibit the activation of the inflammatory reaction and to obtain an antioxidant activity both in the tissue and in the blood. Oxidative ozone preconditioning causes an increase in SOD, GSH-Px values.MO, using large auto-hemo-infusion or rectal insufflation technique or ozonized water, could help oxygenate the tissues better, decrease gut inflammation and regulate immune response, help slow down viral growth, regulate circulation and avoid or slow down vascular hypertrophy and consequent hyperemia , especially in the early stages, with obvious benefit at microbiome level.