Aggravated corrosion conditions caused by H2S in mixture of oil, brine and gas are responsible for some of the highest equipment failure rates in the petroleum industry. Thw sulfide scavengers HP1 and HP2 have been developed to protect well equipment and pipeline steel from sulfite cracking, electrochemical corrosion and corrosion fatigue. The desulfurisation efficiency and corrosion inhibition rate of scavengers in multiphase systems were measured in the laboratory. Their desulfurisation efficiency exceeded 90% and the corrosion inhibition rate was up to 98%. Based on the obtained results, the scavengers HP1 and HP2 can be recommended for field test and field application as well. Introduction Hydrogen sulfide gas, H2S, is a naturally occurring gas, often found below the surface of the earth, in zones below which oxidation of minerals does not occur. As a constituent of some oil and gas reservoirs it is generally found in small ercentages of the total fluid, though in some reservoirs H2S maybe found in concentration as high as 30%1. It is known that increasing levels of H2S in produced fluids have been bserved since waterflooding began. The biogenic production of H2S is certainly a cause of this problem in many of these reservoirs. The problems associated with sour production are well known: toxic, corrosion, excess solids, emulsion and surface equipment problems, and the necessity to remove H2S prior to sale. Multi millions dollars are spent every year on detection and mitigation of weight loss and other kinds of corrosion in oil and gas industry equipment. Although an abundance of literature describing the abatement of hydrogen sulfide in gas and drilling fluid systems is available, these techniques and environments do not appear to have significant utility in oilfield waterflood operations. Thought the methods like aeration, bacteria, chemical scavengers 2,3 metallic salt and oxide beds4,5, and oxidizers6,7 used in other industries-such as the geothermal, pulp and paper, and wastewater industries have some application in oilfield production, the most of them appear impractical because of cost and compatibility consideration. The purpose of this paper is to present a potential solution to the problem that involves the laboratory testing on H2S scavenger and corrosion control effects of a new H2S scavenger which is designed for injection into the reservoir with the injection water and for near wellbore treatment. In order to better understand the problem, the kinds of corrosion and mechanism caused by hydrogen sulfide and its commercial scavenger will be briefly reviewed.
Characterization of HIV-1 strains is important for surveillance of the HIV-1 epidemic. In Vietnam HIV-1-infected pregnant women often fail to receive the care they are entitled to. Here, we analyzed phylogenetically HIV-1 env sequences from 37 HIV-1-infected pregnant women from Ha Noi (n = 22) and Hai Phong (n = 15), where they delivered in [2005][2006][2007]. All carried CRF01_AE in the gp120 V3 region. In 21 women CRF01_AE was also found in the reverse transcriptase gene. We compared their env gp120 V3 sequences phylogenetically in a maximum likelihood tree to those of 198 other CRF01_AE sequences in Vietnam and 229 from neighboring countries, predominantly Thailand, from the HIV-1 database. Altogether 464 sequences were analyzed. All but one of the maternal sequences colocalized with sequences from northern Vietnam. The maternal sequences had evolved the least when compared to sequences collected in Ha Noi in 2002, as shown by analysis of synonymous and nonsynonymous changes, than to other Vietnamese sequences collected earlier and/or elsewhere. Since the HIV-1 epidemic in women in Vietnam may still be underestimated, characterization of HIV-1 in pregnant women is important to observe how HIV-1 has evolved and follow its molecular epidemiology.
Radio direction finding system is a system that determines the direction or coordinates of radio signal sources. The main function of this system is to determine the direction of arrival (DOA) of an incident radio wave. DOA information plays an important role in array signal processing and has many applications in communications, radar, seismic survey, etc. In this study, we propose a method to estimate the DOA by using the simulated signal dataset obtained at the linear antenna array (ULA) and the suitable Long Short-Term Memory (LSTM) network model. The performance of the method is evaluated based on the root mean square error (RMSE) parameter and then is compared with 2 other algorithms, multiple signal classification (MUSIC) and deep neural network (DNN) in different cases such as deviation of incoming signals, variation of signal-to-noise ratio (SNR), and coherent incoming signals. The obtained results have shown that the proposed method has significantly improved accuracy compared to other methods.
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