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Optimal Feedback Control of Oil Reservoir Waterflooding Processes

International Journal of Automation and computing 2016年第1期13卷 73-80页

作者： a.s.grema Yi Cao school of Energy Environment & Agrifood Cranfield University

Waterfiooding is a process where water is injected into an oil reservoir to supplement its natural pressure for increment in productivity. The reservoir properties are highly heterogeneous, its states change as production progresses which require varying injection and production settings for economic recovery. As water is injected into the reservoir, more oil is expected to be produced. There is also likelihood that water is produced in association with the oil. The worst case is when the injected water meanders through the reservoir, it bypasses pools of oil and gets produced, Therefore, any effort geared toward finding the optimal settings to maximize the value of this venture can never be over emphasized. Waterflooding can be formulated as an optimal control problem. However, traditional optimal control is an open-loop solution, hence cannot cope with various uncertainties inevitably existing in any practical systems. Reservoir models are highly uncertain. Its properties are known with some degrees of certainty near the well-bore region only. In this work, a novel data-driven approach for control variable （CV） selection was proposed and applied to reservoir waterflooding process for a feedback strategy resulting in optimal or near optimal operation. The results indicated that the feedback control method was close to optimal in the absence of uncertainty. The loss recorded in the value of performance index, net present value （NPV） was only 0.26%. Furthermore, the new strategy performs better than the open-loop optimal control solution when system/model mismatch was considered. The performance depends on the scale of the uncertainty introduced. A gain in NPV as high as 30.04% was obtained.

关键词： Oil reservoir management intelligent wells optimal control theory feedback control geological uncertainty.

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Effects of Using softwood Pellet Biochar Prepared at Different Temperatures with Grass Chippings on Retention of Heavy Metals in Contaminated soils

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Open Journal of Polymer Chemistry 2024年第3期14卷 146-166页

作者： Kyari Umar Dunoma Limin Ma Xingquan shu Haiyan Yu Weiwei Zhang Chengcheng Bu Yong-sik Wang Jiahong Luo Guangyao Chen Jinpeng Yu Ru Zhang Yuchen Han Haoyu Zeng Matthew s. Wisseh Amina grema Mustafa Mohammad Auwal saidu Mufidat Mamman Khan College of Environmental science and Engineering Tongji University Shanghai China Key Laboratory of Yangtze River Water Environment Ministry of Education Tongji University Shanghai China Environmental Assessment Department Federal Ministry of Environment Abuja Nigeria

Heavy metals have been viewed as hazardous environmental pollutants, and anthropogenic activities due to their high toxicity and persistent nature in the environment. Anthropogenic activities such as artisanal mining, industrial activities, improper usage of fertilizers and pesticides, and indiscriminate open waste disposal bring about an increase in the presence of heavy metals in the environment. In the Keffi Metropolis, different elements lead to land contamination which debilitates soil quality, plant survival, human well-being, and the environment as a result of extensive dispersion or quantity of heavy metals in the soil and water. In recent years, biochar has emerged as a promising soil amendment for mitigating heavy metal pollution due to its unique physicochemical properties. This paper provides the effects of softwood pellet biochar on the retention of heavy metals in contaminated soils. A microcosm experiment was carried out to investigate the effects of biochar on the retention of heavy metals in contaminated soils. This research aimed to give an overview of the effects of softwood biochar at different temperatures (550˚C and 700˚C) on the retention of heavy metals and metalloids released from the soil during water inundation. The results show that the addition of organic matter (grass chippings) minimizes heavy metal mobilization. Also, biochar at high temperatures is more effective than those at low temperatures. The expected outcome of the research analysis includes providing insights into the role of biochar in retaining heavy metal contamination and further understanding the use of biochar as a sorbent for the management of contaminated soil.

关键词： softwood Biochar Heavy Metal Contaminated soil Grass Chips Keffi Metropolis Microcosm

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Outpatient prevention counseling for malaria in northwest Nigeria: A single-centre descriptive cross-sectional study

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Asian Pacific Journal of Tropical Medicine 2020年第5期13卷 214-220页

作者： Godpower Chinedu Michael Bukar Alhaji grema Ibrahim Aliyu Muhammad Baba Usman ZainabAbdulazeez Umar Department of Family Medicine Aminu Kano Teaching HospitalKano Nigeria Department of Paediatrics Bayero University Kano/Aminu Kano Teaching HospitalKanoNigeria Department of Paediatrics Aminu Kano Teaching HospitalKanoNigeria

Objective:To assess the proportion of caregivers of children and patients who received malaria prevention counseling from their healthcare provider at the time of outpatient malaria ***:This was a descriptive cross-sectional study involving 353 randomly selected adult patients and caregivers of children attending the general and paediatric outpatient clinics of a Nigerian *** interviewer-administered questionnaire was used to collect data on participants'sociodemographics and last malaria-episode *** square test and logistic regression analysis were used to determine factors associated with and predictors of receiving malaria-prevention counseling,***:The mean age of the respondents was(33.6±9.6)years;they were predominantly females(257,72.8%).Most had at least secondary-level education(304,86.1%);the family size was mostly 1-6 persons in 202(57.2%)*** were treated mostly by doctors 256(72.5%),but only 132(37.4%)received malaria prevention ***-level(x2=5.42,P=0.02),family size(Fisher's exact,P=0.01),place of treatment(Fisher's exact,P=0.0002),pretreatment malaria test(x2=9.48,P=0.002),who prescribed treatment(Fisher's exact P=0.001),consultation time(x2=22.09,Ps demand for malaria prevention counseling(x2=36.59,Pssociated with receiving malaria prevention ***,consultation time[Odd ratio(OR)=2.38,95%confidence interval(CI):1.28,4.40,P=0.006]and previous demand for malaria prevention counseling(OR=3.62,95%CI:2.15,6.10,Ps of receiving ***:The proportion of respondents that received malaria prevention counseling was surprisingly *** offers opportunity for policy review towards improving the quality of outpatient malaria care through alternative strategies for giving malaria prevention information,especially in busy clinics where consultation time is constrained.

关键词： Counseling Healthcare provider Malaria Outpatients Prevention

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Conjugate Heat Transfer Predictions of Gas Turbine Hot Walls Jets Cooling: Influence of short Hole Grid Resolutions Using Computational Fluid Dynamics*

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Journal of Power and Energy Engineering 2023年第10期11卷 1-16页

作者： Abubakar M. El-Jummah shehu A. Abdulrahman Alhaji s. grema Department of Mechanical Engineering University of Maiduguri Maiduguri Nigeria Department of Mechanical Engineering Nigerian Army University Biu Borno Nigeria Department of Chemical Engineering University of Maiduguri Maiduguri Nigeria

short hole investigations relevant to gas turbine (GT) hot walls cooling heat transfer techniques, were carried out using computational fluid dynamics (CFD) combined with conjugate heat transfer (CHT) code. The CFD software are commercial ones: ICEM for grid modelling and ANsYs Fluent for the numerical calculation, where symmetrical application prevails. The CFD CHT predictions were undertaken for Nimonic-75 metal walls with square (152.4 mm) arrays of 10 holes, whereby the lumped heat capacitance method was applied in order to determine the surface average heat transfer coefficient (HTC), h (W/msup>2sup> K) and the dimensionless Nusselt number, Nu. The major parameters considered for the short hole geometries are the pitch to diameter, X/D and length to diameter, L/D ratios and both were varied with range of D values, but X of 15.24 mm and L of 6.35 mm kept constant. Also applied, are variable mass flux, G (kg/s∙msup>2sup>) and were used in predicting the flow aerodynamics in the short holes. The predictions were for classic thermal entry length into a round hole, as vena contracta, flow separation and reattachment dominates the holes, hence the development of thermal profile through the depth of the GT hot walls. Additionally, the acceleration of the flow along the wall surfaces as it approaches the holes, was a significant part of the overall heat transfer. This was shown to be independent of the hole length, even though the L/D parameter is a critical component to enhanced heat transfer. The CFD CHT predictions showed that validation of the HTC h, Nu and pressure loss, ∆P are in better agreement with measured data and within reasonable acceptance. The ∆P agreement signifies that the aerodynamics were predicted correctly, which is also the reason why the HTC expressed per wall hole approach surface area and Nu were better predicted. This illustrates how effective and efficient the wall internal heat transfer cooling is for gas turbine hot wall heat transfer

关键词： Lumped Heat Capacitance Thermal Entry Length symmetrical Application Flow separation Flow Reattachment

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