Empirical analysis of localized casing wear with variations in contact pressure and drilling conditions

Im Wettkampf die Grenzen der Kohlenwasserstoff- und Geothermie Förderung sowie Speicherung stetig zu übertreffen und optimieren, wurden horizontale Bohrungen, tiefe Ablenkungsbohrungen und Bohrungen mit großem Neigungswinkel (ERD Bohrungen) zum heutigen Standard. Bei der Planung solcher Projekte sowie Ablenkungen, wirken sich Vorgänge wie Räumen (reaming), Bohren (drilling), Rotation off-bottom und das Ein- und Ausfahren der Bohrgestänge enorm auf die Futterrohr Beschaffenheit aus. Durch das Aufeinandertreffen und dem herrschenden Kontakt zwischen dem Bohrstrang und der Innenwand des Futterrohrs, tritt eine stärkere Abnutzung des Materials auf seitens des Futterrohrs, besonders an den Verbindungsstellen des Bohrstrangs, auf. Dies führt entweder zu einem ungleichmäßigen kreisförmigen Schwund der Futterrohr-Stärke, oder bei längerem kontinuierlichem Kontakt gegen die Innenwand des Futterrohrs, zu einer punktuellen tiefen Verschleißrille. Ein dynamischer Futterrohr-Verschleiß ist aufgrund der Vielzahl von Variablen, ein komplexes, zu simulierendes Phänomen, da die Variablen das nicht-lineare Verschleißverhalten beeinflussen. Die Verschleißintensität wird durch individuelle Kombinationen von Betriebsbelastungen (verändernde Kraft-Flächen-Verteilungen) beeinflusst. Metallurgische Eigenschaften (Werkstoffhärte und Streckgrenze) und vorherrschende tribologische Mechanismen (Oberflächenrauheit, Reibungsfaktoren und Verschleißart) kommen zum Tragen. Damit Verschleißsimulationsgleichungen möglichst genau sind, müssen die erforderlichen Reibungs- und Verschleißfaktoren experimentell durch umfangreiche Versuche bestimmt werden. Um diese Anforderung zu erfüllen, besteht der erste Schritt dieser Forschung darin, vorhandene mathematische Modelle und konventionelle Bohrlochplanungssoftwares zu analysieren. Daraus folgt die Bestimmung von Parametern, die für ein umfassendes Verschleißtestverfahren in Bezug auf variable Seitenkraft, Bohrstrangdrehzahl, axiale Bewegung und Fluidtyp, notwendig sind. Der zweite Schritt und somit der Fokus dieser Studie ist die Planung, Konstruktion und Anwendung eines vollwertigen Verschleißmodels zur Reproduktion von Reibungs- und Verschleißfaktoren unter Feldbedingungen. Die entwickelte Verschleißanlage ermöglicht Abrieb verschiedener Futterrohr-Materialien unter diversen Betriebslasten und verschieden Arten von Schmiermitteln zu simulieren. Unter Anwendung nahezu gleicher Betriebslasten, wurden die Verschleißprozesse für Stahl-, Glasfaser- und Kohlefaser-Futterrohrs untereinander verglichen. Der Umfang der Testreihe beinhaltete bislang 14 Tests unter Anwendung eines Schlammbasierenden Schmiermittels oder Wasser. Vergleiche zwischen den erbrachten Ergebnissen, in Bezug auf Reibungs- und Verschleißfaktoren, zeigen eine starke Ähnlichkeit und stehen somit im Einklang mit früheren experimentellen Studien. Nachdem der höchste Verschleißfaktor binnen kurzer Testdauer erreicht wurde, ist zu beobachten, dass dieser nach einer Verringerung des Druckkontaktes drastisch und stetig sinkt. Dieses Phänomen ist bei allen getesteten Materialien unter bestimmten Betriebslasten und Bohrszenarien zu verzeichnen und kann als einen genaueren Richtwert für Feld Ereignisse genutzt werden. Des Weiteren können mithilfe der gemessenen Werte des Reibungsfaktors, die Spanne der Belastungsdruckgrenze (Contact Pressure Threshold) an den Futterrohren genauer bestimmt werden. Eine Verschleißvolumengleichung, basierend auf den experimentellen Ergebnissen, wird als Teil der Testergebnisse präsentiert. Anhand der ermittelten Werte sowie Trends der Versuchsergebnisse, können Vorhersagen, bezüglich des Verschleißes, getroffen werden. Indem weiterer Stahlsorten, Durchmesser und neue Futterrohr-Materialien in den experimentellen Umfang einbezogen werden, kann die Anlage unter praxisnahen Bedingungen Verschleißverhalten darstellen. Hersteller für Futterrohre und Verbindungen profitieren von diesen Simulationen, um genauere Werte bei ihrer Herstellungsweise integrieren zu können. Durch die Anlage simulierten Feld Bedingungen, können die Werte der Belastungsdruckgrenzen (Contact Pressure Threshold) und Verschleißfaktoren erlangt werden. Diese Werte werden benötigt, um eine empirische Daten Gliederung zu erstellen, welche daraufhin in eine Software integriert werden. Dies vermag den Futterrohr-Verschleiß im Voraus abzuwägen und zu reduzieren, aber ermöglicht gleichzeitig die Flexibilität bei Betriebslasten beizubehalten.In the race to push the limits of hydrocarbon and geothermal production (and storage), deep inclined, horizontal, and ERD wells have become the drilling norm. In building such well trajectories, processes such as drilling, reaming, rotation off-bottom and tripping always affect casing wall thickness due to its interaction with the drillstring (particularly at the tool joints) under high contact forces. This results in either an uneven circumferential thickness reduction or, in case of long continuous contact of a tense drillstring pressed against the casing inner wall, a localized deep wear-groove. Localized dynamic casing wear is a complex phenomenon to simulate due to the number of control variables influencing the non-linear wear behavior. Wear intensity is influenced by individual combinations of service loads (changing force-area distributions), metallurgical properties (material hardness and yield strength) and prevailing tribological mechanisms (surface roughness, friction factors and wear type). For wear simulation models to be accurate, the required friction- and wear factors must be experimentally determined by full-scale tests. To fulfill this requisite, the first step of this research is to analyze existing mathematical models and conventional well planning software to establish parameters for a full-scale wear test method in terms of variable side force, drillstring RPM, axial reciprocation, and fluid type. The design, construction, and application of a full-scale wear frame to reproduce friction- and wear factors under field conditions is the second step, and the core focus of this study. The wear frame is designed to incorporate different casing materials under a range of operational loads and lubrication conditions, and wear scenarios under similar service loads have been compared for steel, fibered glass and fibered carbon casings. A total of 14 wear tests have been carried out in the study time-frame for the casing materials under water and mud lubrication conditions. A comparison of test results shows good consistency and agreement with previous experimental studies in terms of friction and wear factors. After the initial peak values, the wear factor is observed to decline drastically to a steady-drop range upon contact pressure reduction. For all tested materials, this steady range of values can provide a good estimate of field wear volume over time under particular service loads and drilling scenarios. Also, the measured steady values of friction factors help determine close ranges on contact pressure threshold for the casings. A proposed wear volume equation based on the experimental results is presented as a part of test results. It has been observed from the detected trends in the test results that repeated wear tests can make casing wear predictable. With the inclusion of more steel grades, diameters and new casing materials into the experimental scope, the wear frame can be used to develop a comprehensive record of wear performance under different field scenarios for casing and tool joint manufacturing industry. Attribution of wear factors and contact pressure thresholds to specific field conditions via a wear test database, and its integration into a software solution, can fill gaps to help reduce casing wear while retaining flexibility on operational loads

Studies of the silkworm enzyme activity and their correlations with economic variables

The experiment was conducted to analyse the larval performance and economic traits of bivoltine silkworm breeds of silkworm (SK-1, SK-6, SK-22, SK-28, SK-33, CSR4, CSR2, NB4D2, DUN6 and APS4) during spring season. The haemolymph total protein, succinate and gultamate dehydrogenase activities were estimated and their correlation with economic traits were also worked out. The results of the study confirmed that among ten bivoltine silkworm breeds, highest haemolymph SDH activity of 3.47 µmoles/ml/mgprotein/min was recorded in the silkworm breed SK1 and least SDH activity of 1.58 µmoles/ml/mg protein/min was recorded in the breed APS4. The highest peak of succinate dehydrogenase activity of 2.65 µmoles/ml/mg protein/min was observed on 7th day of the 5th instar and lowest peak of succinate dehydrogenase activity of 2.39 µmoles/ml/mg protein/min was observed on 4th day of the 5th instar. GDH activity of 0.46 µmoles/ml/mg protein/min was recorded highest in the silkworm breed SK1 and lowest of 0.15 µmoles/ml/mg protein/min was recorded in silkworm breed APS4. The highest peak of haemolymph GDH of 0.36 µmoles/ml/mg protein/min was recorded on 7th day of 5th instar and lowest peak of 0.26 µmoles/ml/mg protein/min was recorded on 4th day of 5th instar. The correlational studies revealed that haemolymph total protein, SDH and GDH were found to be positively corelated with yield by weight and number (cocoon), weight of mature larvae, shell weight ,cocoon weight, shell ratio percent, silk productivity, rate of pupation, fecundity, raw silk percentage  and length of filament. Thus, the study revealed that silkworm breeds like SK1, SK6, SK22 and SK28 as productive breeds and hence may be used for future breeding programmes for evolution of new robust silkworm breed

Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial

Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124. Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid (5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18). Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of 5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98). Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a randomised trial

Multi-Objective Analysis of a CHP Plant Integrated Microgrid in Pakistan

In developing countries like Pakistan, the capacity shortage (CS) of electricity is a critical problem. The frequent natural gas (NG) outages compel consumers to use electricity to fulfill the thermal loads, which ends up as an increase in electrical load. In this scenario, the authors have proposed the concept of a combined heat & power (CHP) plant to be a better option for supplying both electrical and thermal loads simultaneously. A CHP plant-based microgrid comprising a PV array, diesel generators and batteries (operating in grid-connected as well as islanded modes) has been simulated using the HOMER Pro software. Different configurations of distributed generators (DGs) with/without batteries have been evaluated considering multiple objectives. The multiple objectives include the minimization of the total net present cost (TNPC), cost of generated energy (COE) and the annual greenhouse gas (GHG) emissions, as well as the maximization of annual waste heat recovery (WHR) of thermal units and annual grid sales (GS). These objectives are subject to the constraints of power balance, battery operation within state of charge (SOC) limits, generator operation within capacity limits and zero capacity shortage. The simulations have been performed on six cities including Islamabad, Lahore, Karachi, Peshawar, Quetta and Gilgit. The simulation results have been analyzed to find the most optimal city for the CHP plant integrated microgrid

Designing Functionally Substituted Pyridine-Carbohydrazides for Potent Antibacterial and Devouring Antifungal Effect on Multidrug Resistant (MDR) Strains

The emergence of multidrug-resistant (MDR) pathogens and the gradual depletion of available antibiotics have exacerbated the need for novel antimicrobial agents with minimal toxicity. Herein, we report functionally substituted pyridine carbohydrazide with remarkable antimicrobial effect on multi-drug resistant strains. In the series, compound 6 had potent activity against four MDR strains of Candida spp., with minimum inhibitory concentration (MIC) values being in the range of 16-24 mu g/mL and percentage inhibition up to 92.57%, which was exceptional when compared to broad-spectrum antifungal drug fluconazole (MIC = 20 mu g/mL, 81.88% inhibition). Substitution of the octyl chain in 6 with a shorter butyl chain resulted in a significant anti-bacterial effect of 4 against Pseudomonas aeruginosa (ATCC 27853), the MIC value being 2-fold superior to the standard combination of ampicillin/cloxacillin. Time-kill kinetics assays were used to discern the efficacy and pharmacodynamics of the potent compounds. Further, hemolysis tests confirmed that both compounds had better safety profiles than the standard drugs. Besides, molecular docking simulations were used to further explore their mode of interaction with target proteins. Overall results suggest that these compounds have the potential to become promising antimicrobial drugs against MDR strains

Designing Functionally Substituted Pyridine-Carbohydrazides for Potent Antibacterial and Devouring Antifungal Effect on Multidrug Resistant (MDR) Strains

The emergence of multidrug-resistant (MDR) pathogens and the gradual depletion of available antibiotics have exacerbated the need for novel antimicrobial agents with minimal toxicity. Herein, we report functionally substituted pyridine carbohydrazide with remarkable antimicrobial effect on multi-drug resistant strains. In the series, compound 6 had potent activity against four MDR strains of Candida spp., with minimum inhibitory concentration (MIC) values being in the range of 16–24 µg/mL and percentage inhibition up to 92.57%, which was exceptional when compared to broad-spectrum antifungal drug fluconazole (MIC = 20 µg/mL, 81.88% inhibition). Substitution of the octyl chain in 6 with a shorter butyl chain resulted in a significant anti-bacterial effect of 4 against Pseudomonas aeruginosa (ATCC 27853), the MIC value being 2-fold superior to the standard combination of ampicillin/cloxacillin. Time-kill kinetics assays were used to discern the efficacy and pharmacodynamics of the potent compounds. Further, hemolysis tests confirmed that both compounds had better safety profiles than the standard drugs. Besides, molecular docking simulations were used to further explore their mode of interaction with target proteins. Overall results suggest that these compounds have the potential to become promising antimicrobial drugs against MDR strains