Modeling well performance in compartmentalized gas reservoirs

Predicting the performance of wells in compartmentalized reservoirs can be quite challenging to most conventional reservoir engineering tools. The purpose of this research is to develop a Compartmentalized Gas Depletion Model that applies not only to conventional consolidated reservoirs (with constant formation compressibility) but also to unconsolidated reservoirs (with variable formation compressibility) by including geomechanics, permeability deterioration and compartmentalization to estimate the OGIP and performance characteristics of each compartment in such reservoirs given production data. A geomechanics model was developed using available correlation in the industry to estimate variable pore volume compressibility, reservoir compaction and permeability reduction. The geomechanics calculations were combined with gas material balance equation and pseudo-steady state equation and the model was used to predict well performance. Simulated production data from a conventional gas Simulator was used for consolidated reservoir cases while synthetic data (generated by the model using known parameters) was used for unconsolidated reservoir cases. In both cases, the Compartmentalized Depletion Model was used to analyze data, and estimate the OGIP and Jg of each compartment in a compartmentalized gas reservoir and predict the subsequent reservoir performance. The analysis was done by history-matching gas rate with the model using an optimization technique. The model gave satisfactory results with both consolidated and unconsolidated reservoirs for single and multiple reservoir layers. It was demonstrated that for unconsolidated reservoirs, reduction in permeability and reservoir compaction could be very significant especially for unconsolidated gas reservoirs with large pay thickness and large depletion pressure

A Review of Studies on Real Estate Investment Performance in Nigeria

This study has been conducted to review the studies conducted on property investment performance in Nigeria with the aim of providing a clear insight into the trend, authors’ affiliations, performance measurement techniques and the geographical focus of these studies. Published and unpublished research works in this research area were sourced and reviewed. The data and information used were sourced from online databases such as Google, Google Scholar, ScienceDirect, ProQuest, and ResearchGate. Printed journals (local and international), published and unpublished Masters and PhD theses were also among the sources of the data used. Descriptive statistics were used to analyse the authors’ contributions, affiliations, geographical focus and the annual research trend of real estate investment performance in Nigeria and the results reported. The study found that the first study conducted on the performance of real estate investment was Olaleye (2000) followed by Olaleye (2002). Olaleye, A., Oyewole, M. O. and Dabara, D. I. were found to be the most active and leading researchers on this research area with contributory scores of 3.87, 3.61 and 3.21 respectively. On the average, about 2 studies on the subject were carried out annually with focus majorly on the Lagos property market, Southwest Nigeria. The review further revealed that nominal rate of returns, Sharpe index and coefficient of variation were the common performance measurement indices often adopted by majority of the previous authors. This study recommends that collaborative effort should be established among scholars of estate management and practicing estate surveyors and valuers with a view to bridging the gap between theory and practice and boosting property data banking in Nigeria. The geographical scope of real estate investment performance in Nigeria needs to be expanded to adequately cover all the regional property markets

Drag Reduction with Biopolymer-Synthetic Polymer Mixtures in Oil-Water Flows: Effect of Synergy

The search for lower cost materials that reduce pressure drop in fluid transport systems in oil and gas industries to conserve pumping energy is of paramount importance. Polymers are known to reduce pressure drop in pipeline oil-water flows in a process referred to as drag reduction (DR). The effect of partially hydrolysed polyacrylamide, polyethylene oxide, Aloe Vera mucilage and their mixtures as drag reducing polymers (DRPs) on pressure gradient (pressure drop; Δp) in pipeline oil-water flows were studied. The experiment was carried out in flow rig with 0.02-m diameter straight unplasticised polyvinylchloride (uPVC) pipe, two centrifugal pumps, control valves and two storage tanks. Tap water (ρ = 997 kg/m3 and µ = 0.89 cP) and diesel (ρ = 832 kg/m3 and µ = 1.66 cP) were used as the test fluid at ambient condition. The polymer mixture total concentration (MTC) of 30 and 400 ppm at different mixing proportion, mixture Reynolds number (Remix) and oil input volume were investigated. The results show increase in pressure gradient with increase in oil input volume in both single-phase water flow and oil-water flow before adding drag reducing polymers (DRPs). However, Δp decreased after adding DRPs with increase in Reynolds number (Re) or Remix and decrease in the oil-phase Re, and vice versa. The results further showed higher reduction in pressure drop by the polymer mixture than in each of the polymer used at the same conditions. The rigidness of the biopolymer was improved by adding synthetic polymers which resulted to increase in DR efficiency

A Review of Studies on Real Estate Investment Performance in Nigeria

This study has been conducted to review the studies conducted on property investment performance in Nigeria with the aim of providing a clear insight into the trend, authors’ affiliations, performance measurement techniques and the geographical focus of these studies. Published and unpublished research works in this research area were sourced and reviewed. The data and information used were sourced from online databases such as Google, Google Scholar, ScienceDirect, ProQuest, and ResearchGate. Printed journals (local and international), published and unpublished Masters and PhD theses were also among the sources of the data used. Descriptive statistics were used to analyse the authors’ contributions, affiliations, geographical focus and the annual research trend of real estate investment performance in Nigeria and the results reported. The study found that the first study conducted on the performance of real estate investment was Olaleye (2000) followed by Olaleye (2002). Olaleye, A., Oyewole, M. O. and Dabara, D. I. were found to be the most active and leading researchers on this research area with contributory scores of 3.87, 3.61 and 3.21 respectively. On the average, about 2 studies on the subject were carried out annually with focus majorly on the Lagos property market, Southwest Nigeria. The review further revealed that nominal rate of returns, Sharpe index and coefficient of variation were the common performance measurement indices often adopted by majority of the previous authors. This study recommends that collaborative effort should be established among scholars of estate management and practicing estate surveyors and valuers with a view to bridging the gap between theory and practice and boosting property data banking in Nigeria. The geographical scope of real estate investment performance in Nigeria needs to be expanded to adequately cover all the regional property markets

ERGONOMIC EVALUATION OF PACKAGING WORKERS’ POSTURE IN A FOOD MANUFACTURING COMPANY

This study conducted an ergonomic evaluation of the working posture of workers engaged in various processes in the packaging section of a food manufacturing company. Workers in the packaging section of the food manufacturing company were divided into operating, folding, packing, carton wrapping and palletizing. Forty of the workers in the packaging section were placed under observation through video recording of their daily activities for a period of three months to obtain their working postures. Rapid Upper Limb Assessment (RULA) was used to analyze the working postures in order to obtain their ergonomic risk levels. Computer codes for RULA were written for quick and easy evaluation of upper arm, lower arm, wrist, wrist twist, neck, trunk and leg postures. The results from RULA indicated that 25% of the workers in the operating and folding units were exposed to medium ergonomic risk level; 30% of the workers in the packing unit and 10% of the workers in the carton wrapping unit were exposed to high ergonomic risk level while 10% of the workers in the palletizing unit were exposed to a very high ergonomic risk level. The study concluded that workers in the packaging section of the food manufacturing company were exposed to between medium and very high ergonomic risk levels of working posture necessitating the need to change the conditions of their workstations

ERROR COMMITTED BY BIOLOGY STUDENTS AND THEIR ACADEMIC ACHIEVEMENT AT THE SENIOR SECONDARY SCHOOLS

ABSTRACT This paper investigated the relationship between frequencies of errors committed and academic achievement b

ERGONOMIC EVALUATION OF PACKAGING WORKERS’ POSTURE IN A FOOD MANUFACTURING COMPANY

This study conducted an ergonomic evaluation of the working posture of workers engaged in various processes in the packaging section of a food manufacturing company. Workers in the packaging section of the food manufacturing company were divided into operating, folding, packing, carton wrapping and palletizing. Forty of the workers in the packaging section were placed under observation through video recording of their daily activities for a period of three months to obtain their working postures. Rapid Upper Limb Assessment (RULA) was used to analyze the working postures in order to obtain their ergonomic risk levels. Computer codes for RULA were written for quick and easy evaluation of upper arm, lower arm, wrist, wrist twist, neck, trunk and leg postures. The results from RULA indicated that 25% of the workers in the operating and folding units were exposed to medium ergonomic risk level; 30% of the workers in the packing unit and 10% of the workers in the carton wrapping unit were exposed to high ergonomic risk level while 10% of the workers in the palletizing unit were exposed to a very high ergonomic risk level. The study concluded that workers in the packaging section of the food manufacturing company were exposed to between medium and very high ergonomic risk levels of working posture necessitating the need to change the conditions of their workstations

Effect of early tranexamic acid administration on mortality, hysterectomy, and other morbidities in women with post-partum haemorrhage (WOMAN): an international, randomised, double-blind, placebo-controlled trial

Background Post-partum haemorrhage is the leading cause of maternal death worldwide. Early administration of tranexamic acid reduces deaths due to bleeding in trauma patients. We aimed to assess the effects of early administration of tranexamic acid on death, hysterectomy, and other relevant outcomes in women with post-partum haemorrhage. Methods In this randomised, double-blind, placebo-controlled trial, we recruited women aged 16 years and older with a clinical diagnosis of post-partum haemorrhage after a vaginal birth or caesarean section from 193 hospitals in 21 countries. We randomly assigned women to receive either 1 g intravenous tranexamic acid or matching placebo in addition to usual care. If bleeding continued after 30 min, or stopped and restarted within 24 h of the first dose, a second dose of 1 g of tranexamic acid or placebo could be given. Patients were assigned by selection of a numbered treatment pack from a box containing eight numbered packs that were identical apart from the pack number. Participants, care givers, and those assessing outcomes were masked to allocation. We originally planned to enrol 15 000 women with a composite primary endpoint of death from all-causes or hysterectomy within 42 days of giving birth. However, during the trial it became apparent that the decision to conduct a hysterectomy was often made at the same time as randomisation. Although tranexamic acid could influence the risk of death in these cases, it could not affect the risk of hysterectomy. We therefore increased the sample size from 15 000 to 20 000 women in order to estimate the effect of tranexamic acid on the risk of death from post-partum haemorrhage. All analyses were done on an intention-to-treat basis. This trial is registered with ISRCTN76912190 (Dec 8, 2008); ClinicalTrials.gov, number NCT00872469; and PACTR201007000192283. Findings Between March, 2010, and April, 2016, 20 060 women were enrolled and randomly assigned to receive tranexamic acid (n=10 051) or placebo (n=10 009), of whom 10 036 and 9985, respectively, were included in the analysis. Death due to bleeding was significantly reduced in women given tranexamic acid (155 [1·5%] of 10 036 patients vs 191 [1·9%] of 9985 in the placebo group, risk ratio [RR] 0·81, 95% CI 0·65–1·00; p=0·045), especially in women given treatment within 3 h of giving birth (89 [1·2%] in the tranexamic acid group vs 127 [1·7%] in the placebo group, RR 0·69, 95% CI 0·52–0·91; p=0·008). All other causes of death did not differ significantly by group. Hysterectomy was not reduced with tranexamic acid (358 [3·6%] patients in the tranexamic acid group vs 351 [3·5%] in the placebo group, RR 1·02, 95% CI 0·88–1·07; p=0·84). The composite primary endpoint of death from all causes or hysterectomy was not reduced with tranexamic acid (534 [5·3%] deaths or hysterectomies in the tranexamic acid group vs 546 [5·5%] in the placebo group, RR 0·97, 95% CI 0·87-1·09; p=0·65). Adverse events (including thromboembolic events) did not differ significantly in the tranexamic acid versus placebo group. Interpretation Tranexamic acid reduces death due to bleeding in women with post-partum haemorrhage with no adverse effects. When used as a treatment for postpartum haemorrhage, tranexamic acid should be given as soon as possible after bleeding onset. Funding London School of Hygiene & Tropical Medicine, Pfizer, UK Department of Health, Wellcome Trust, and Bill & Melinda Gates Foundation

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030