Prediction of the Asphaltene Precipitation Envelope Curve (APE) and the Amount of Precipitated Asphaltene from Crude Oil in Asphaltene Precipitation Region

, M.Sc. Thesis Sharif University of Technology Kohanpour, Sobhan (Author) ; Jamshidi, Saeid (Supervisor) ; Taghikhani, Vahid (Supervisor)

Abstract

Asphaltene precipitation has become one of the common challenges in oil fields worldwide. The aim of this study was to develop simple, efficient, and accurate correlations for predicting the asphaltene precipitation envelope and the weight percentage of precipitated asphaltene from crude oil. To this end, symbolic regression was employed as an effective tool for modeling asphaltene precipitation behavior under data-scarce conditions. This method demonstrated accurate system behavior prediction due to its ability to derive simple and interpretable mathematical relations. In this study, upper and lower threshold equations for asphaltene precipitation were developed in the temperature range of...

Buckling behavior of the anchored steel tanks under horizontal and vertical ground motions using static pushover and incremental dynamic analyses

, Article Thin-Walled Structures ; Volume 112 , 2017 , Pages 173-183 ; 02638231 (ISSN) Sobhan, M. S ; Rahimzadeh Rofooei, F ; Khajeh Ahmad Attari, N ; Sharif University of Technology

Elsevier Ltd 2017

Abstract

This paper investigates the static and dynamic buckling of an anchored cylindrical steel tank subjected to horizontal and vertical ground acceleration. The buckling capacity of the tank is estimated using static pushover (SPO) and incremental dynamic analyses (IDA). Appropriate load patterns due to the horizontal and vertical components of ground excitations are utilized for SPO analyses. The buckling capacity curves and critical buckling loads computed using SPO analyses are compared to those obtained from IDA. A proper vertical to horizontal acceleration ratio (av/ah) for SPO analysis is proposed that leads to good agreement between SPO and IDA results. © 2017

Investigating the Effect of Soil-Structure Interaction on the Buckling Behavior of Anchored Steel Cylindrical Tanks using Absorbing Boundaries

, M.Sc. Thesis Sharif University of Technology Khaki, Taha (Author) ; Rahimzadeh Rofooei, Fayaz (Supervisor) ; Sobhan, Mohammad Saeed (Supervisor)

Abstract

This research investigates the effect of soil-structure interaction on the buckling behavior of an above-ground storage tanks. For this purpose, a steel tank with a height-to-diameter ratio of 0.4 was selected. Four types of support conditions including a fixed-based condition and three soil islands with a depth of 30 meters, assuming a uniform stiff soil and a two-layered soil consisting of stiff and medium soil, and a three-layer soil with stiff, medium, and soft layers. The tank and soil were modeled using the finite element method, and absorbing boundaries were applied around the soil island to simulate the semi-infinite soil domain. After validating the modeling through parametric and...

Seismic Response and Buckling behavior of Aboveground Cylindrical Steel Tanks

, Ph.D. Dissertation Sharif University of Technology Sobhan, Mohammad Saeed (Author) ; Rahimzadeh Rofooei, Fayaz (Supervisor) ; Khaje Ahmad Attari, Nader (Co-Advisor)

Abstract

In this study, the seismic response of aboveground, anchored cylindrical steel tanks subjected to horizontal and vertical ground acceleration is investigated. The buckling capacity of the steel tanks is estimated using static pushover (SPO) and incremental dynamic analyses (IDA). Finite element models of a broad tank and a tall tank with height to diameter ratios (H/D) of 0.40, 0.80 and with a liquid level of 90% of the height of the cylinder were used in this study. Appropriate load patterns due to the horizontal and vertical components of ground excitations are utilized for SPO analyses. The influence of the vertical component of ground acceleration on buckling capacity curve of the tank...