EPR dosimetric studies on strontium sulfate rod for possible use in radiotherapy

Author(s):  
Ramy Amer Fahim ◽  
Yasser S. Soliman ◽  
W.B. Beshir ◽  
Mahmoud H. Abdelgawad ◽  
A.A. Abdel-Fattah ◽  
...  
Keyword(s):  
2021 ◽  
pp. 118592
Author(s):  
Eslam Aboelezz ◽  
Emanuela Bortolin ◽  
Maria Cristina Quattrini ◽  
Sara Della Monaca

Author(s):  
Paola Adriana Coca Suaznabar ◽  
Kazuo Miura ◽  
Celso Kazuyuki Morooka

The purpose of this research is to identify in the literature: causes, factors, case study descriptions and adopted solutions for production losses regarding the petroleum flow in offshore oil wells. Those facts will be organized and structured to identify potential zones of intervention for planning the well maintenance during well design phase to avoid production losses. This paper focuses on four offshore regions: Campos Basin, Gulf of Mexico, North Sea, and West Africa. These regions represent the most significant share of offshore oil production in the world. Data set available in the last thirty five years through academic, technical and governmental reports in the literature were the basis of this study. The procedure was accomplished in three steps: (1) data research (2) analysis of the data (3) guidelines establishment. The main cause of production loss regarding the petroleum flow is the solids deposition in the well/line system, such as hydrates, asphaltenes, wax, scales (barium sulfate, strontium sulfate, calcium sulfate, calcium carbonate, and naturally occurrence radioactive material), and calcium naphthenates. In this work the superposition of graphics (hydrate curve, wax appearance temperature, asphaltene onset pressure, and saturation index) resulted in a region free of solids deposition, denominated as “flow assurance envelope”. The main expected result is to propose a guideline to be used during the well design phase in order to minimize and facilitate the well intervention. The main contributions of this paper to the oil industry are the identification of potential zones of intervention due to solids deposition in the well/line system, the foresight of well intervention before the beginning of the oilfield production, and finally, possibilities to improve the well or intervention design.


1972 ◽  
Vol 45 (9) ◽  
pp. 2773-2775 ◽  
Author(s):  
Toshio Matsuzaki ◽  
Morio Setaka ◽  
V. V. Gromov ◽  
Takao Kwan

SPE Journal ◽  
2021 ◽  
pp. 1-14
Author(s):  
Yue Zhao ◽  
Zhaoyi Dai ◽  
Chong Dai ◽  
Xin Wang ◽  
Samridhdi Paudyal ◽  
...  

Summary Scale inhibitors have been widely used as one of the most efficient methods for sulfate-scale control. To accurately predict the required minimum inhibitor concentration (MIC), we have previously developed several crystallization and inhibition models for pure sulfate scales, including barite, celestite, and gypsum. However, disregarding the wide existence of barium-strontium-sulfate (Ba-Sr-SO4) solid solution in the oil field, no related models have been developed that would lead to large errors in MIC determination. In this study, the induction time of Ba-Sr-SO4 solid solution was measured by laser apparatus with or without different concentrations of scale inhibitor diethylenetriamine penta(methylene phosphonic acid) (DTPMP) at the conditions of barite saturation index (SI) from 1.5 to 1.8, temperature (T) from 40 to 70°C, and [Sr2+]/[Ba2+] ratios from 0 to 15 with celestite SI < 0. The results showed that the Ba-Sr-SO4 solid solution’s induction time increases with the [Sr2+]/[Ba2+] ratio at a fixed barite SI, T, and DTPMP dosage. That means the MIC will be overestimated if it is calculated by the previous semiempirical pure barite crystallization and inhibition models without considering the presence of Sr2+. To resolve such deviations, the novel quantitative Ba-Sr-SO4 solid solution crystallization and inhibition models were developed for the first time. The novel models are in good agreement with the experimental data. They can be used to predict the induction time and MIC more accurately at these common Ba2+ and Sr2+ coexisting scenarios. The observations and new models proposed in this study will significantly improve the barite scale management while Ba2+ and Sr2+ coexist in the oil field. NOTE: Supplementary materials are available in support of this paper and have been published online under Supplementary Data at https://doi.org/10.2118/205367-PA.


1969 ◽  
Vol 52 (4) ◽  
pp. 708-714 ◽  
Author(s):  
William L Hoover ◽  
John C Reagor ◽  
Julianne C Garner

Abstract Samples of plant or animal tissue are digested in a mixture of HNO3, H2SO4, and HClO4. Lead released in the digestion is entrained with strontium sulfate. The sulfate precipitate is separated from the digest and then converted to the carbonate by agitation with ammonium carbonate solution. The carbonate precipitate is dissolved in 1N HNO3, and lead is determined by atomic absorption spectrophotometry. Good recovery of lead (100 ± 3%) was observed except in samples with high calcium content (> 1%). For the latter samples, good recoveries were obtained after separation of the calcium from the digested samples. Moderate quantities of the following elements do not interfere: Al, Fe, P, Sn, Ca, Bi, and Tl. Most elements are soluble as sulfates and, hence, do not interfere. The procedure is rugged. Dry samples containing from 0.5 ppm to 1% lead can be routinely analyzed.


1968 ◽  
Vol 51 (3) ◽  
pp. 719-724
Author(s):  
Bruce C Flann ◽  
John C Bartlet

Abstract Lead in trace quantities is co-precipitated as the sulfate with milligram quantities of strontium carrier, using dilute sulfuric acid. The precipitate is separated from the excess sulfate by centrifuging and is then converted to the carbonate by agitation with ammonium carbonate solution. The carbonate precipitate is separated, dissolved in a slight excess of hydrochloric acid, and then freed of carbon dioxide. The solution, buffered to a pH of 8.8, is immediately extracted with a solution of dithizone in chloroform, and the lead is determined spectrophotometrically. Recoveries are approximately 100% and moderate quantities of the following ions do not interfere: Cd; Co (II) ; Cu (II) ; Fe (II); Fe (II); Mn (II); Hg (II) ; Ni (II) ; Ag (I) ; and Zn. Cyanide buffer is not required, all the chemistry is done in the same centrifuge tube, and many samples can be analyzed simultaneously, using readily available equipment


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