Sharif Digital Repository

We describe a general method for analyzing a nonstationary stochastic process X (t) which, unlike many of the previous analysis methods, does not require X (t) to have any scaling feature. The method is used to study the fluctuations in the daily price of oil. It is shown that the returns time series, y (t) =ln [X (t+1) X (t)], is a stationary and Markov process, characterized by a Markov time scale tM. The coefficients of the Kramers-Moyal expansion for the probability density function P (y,t y0, t0) are computed. P (y,t, y0, t0) satisfies a Fokker-Planck equation, which is equivalent to a Langevin equation for y (t) that provides quantitative predictions for the oil price over times that... 

Wax precipitation may occur in production or transportation of crude oil form field which is a serious problem in petroleum industry. Flow assurance issues concerning wax precipitation make it necessary to develop a precise thermodynamic model to predict the wax appearance temperature and amount of precipitation at different conditions. In this work a new procedure has been proposed to characterize crude oil based on the SARA test considering the wax and asphaltene as single pseudo components. Two scenarios have been investigated for the survey of the crude oil characterization, with and without asphaltene pseudo component. Also, in this work, the Perturbed Chain form of the Statistical... 

In this work the enhancement of gas to hydrate conversion employing the nanographene oxide (NGO)-based nanofluid regarding CO2 capture and sequestration recovery is investigated. A new series of experiments are carried out at different pressures, temperatures, agitation intensities and NGO promoter concentrations by using a newly developed fully automated GTH (gas to hydrate) energy converter. According to the presented results at the 3 MPa and 275.15 K and in the presence of 30 ppm NGO, it is possible to reach a CO2 gas to hydrate conversion of 95% at a low impeller speed in less than 2.5 h, which is quite interesting from an energy consumption standpoint. The presented approach can have... 

In recent years, improving oil recovery (IOR) has become an important subject for the petroleum industry. One IOR method is infill drilling, which improves hydrocarbon recovery from virgin zones of the reservoir. Determining the appropriate location for the infill wells is very challenging and greatly depends on different factors such as the reservoir heterogeneity. This study aims to investigate the effect of reservoir heterogeneity on the location of infill well. In order to characterize the effect of heterogeneity on infill well locations, some geostatistical methods, e.g., sequential gaussian simulation, have been applied to generate various heterogeneity models. In particular, different... 

Multi-phase flows, particularly two-phase flows, are widely used in the industries, hence in order to predict flow regime, pressure drop, heat transfer, and phase change, two-phase flows should be studied more precisely. In the petroleum industry, separation of phases such as water from petroleum is done using rotational flow and vortices; thus, the evolution of the vortex in two-phase flow should be considered. One method of separation requires the flow to enter a long tube in a free vortex. Investigating this requires sufficient knowledge of free vortex flow in a tube. The present study examined the evolution of tube-constrained two-phase free vortex using computational fluid dynamics. The... 

Iran's petroleum industry is facing challenges including maturity of hydrocarbon fields, growing population of the nation that demands additional revenues from petroleum exports, and international economic sanctions that have limited access to technology sources. Restrictions from international technology providers have led managers of the industry enterprises to try to develop their needed technologies inside the country. The Ministry of Petroleum has supervised this and as a result, a technology planning systems has been developed and implemented since 2009. In this paper, an overview of the Iranian petroleum industry is provided from a technology planning perspective. The focus has been... 

In this work, the effect of brine salinity on water-in-oil emulsion flow performance in porous media is studied as it imposes a significant challenge to oil production in the petroleum industry. A crude oil sample from an Iranian oilfield and synthetic brine with different salinities (40-140 g/L salt) are used. The results show that the emulsion viscosity and interfacial tension increase slightly with salinity, while they do not considerably affect the flow behavior. The emulsion stability analysis shows that larger w/o emulsion droplets are formed for higher brine salinity, which potentially block more pore spaces through straining and interception mechanisms. This phenomenon resulted in... 

Oil production strategies define to a large extent the future of the world crude oil market. This paper aims at modelling the long-term world crude oil supply and demand, as well as the global oil price. The main assumption is that non-OPEC and OPEC oil producers act as price-taker and strategic players respectively. The world crude oil demand is modelled as a linear price dependent function. We compare four scenarios to diagnose the OPEC’s supply behaviour: “cartel”, “oligopoly”, “mixed-cartel” and “mixed-oligopoly”. A Mixed Complementarity Problem, MCP, is used to find the Nash equilibrium point of each game scenario. The OPEC countries maximize their individual total discounted profits in... 

Asphaltene deposition in porous media, wellbore and surface facilities has been a severe problem in petroleum industry which causes considerable remediation costs annually. Asphaltenes are heavy and polydisperse fractions of crude oil which are insoluble in n-alkanes such as n-heptane. In this work, three Iranian crude oils were prepared for titration experiments with n-pentane, n-heptane and n-dodecane at different solvent ratios and constant temperature. The experimental data were correlated by perturbed chain form of statistical associating fluid theory (PC-SAFT). The association of asphaltene molecules has been considered in this model with adjusting the uncertain parameters (such as... 

Asphaltene deposition during enhanced oil recovery (EOR) processes is one of the most problematic challenges in the petroleum industry, potentially resulting in flow blockage. Our understanding of the deposition mechanism with emphasis on the rate of the asphaltene deposition is still in its infancy and must be developed through a range of experiments and modelling studies. This study aims to investigate the rate of asphaltene deposition through a visual study under different gas injection scenarios. To visualise the asphaltene deposition, a high-pressure setup was designed and constructed, which enables us to record high-quality images of the deposition process over time. Present research... 

Asphaltene precipitation and deposition causes many serious problems to the petroleum industry from the reservoir to the surface facilities. Therefore, it is important to bring it under control by finding a method to accelerate or slow down its precipitation and deposition. For achieving this purpose two parameters play an important role; onset point of the precipitation and amount of the deposited phase. When asphaltene precipitates, it is capable of depositing in the solution. After the deposition, the solution split into two phases; asphaltene-rich and asphaltene-lean. Determining the amount of the deposited phase needs to distinguish the interface between two phases. In this study, a... 

In this study, biodiesel (FAME) was prepared using a novel heterogeneous catalyst of phosphomolybdic acid (H3PMo12O40, HPMo)/support graphene oxide (GO). The characterization of the catalyst was evaluated by SEM, EDX, Map analysis, TEM, FT-IR, and Raman analyses. The production of biodiesel from waste cooking oil (WCO) was carried out by the electrolysis method. The process of the trans-esterification reaction was optimized by applying the response surface methodology (RSM) based on the central composite design (CCD) approach. The effects of four independent variables of methanol to oil molar ratio (6–12 mol:mol), catalyst weight (0.5–1.5 wt%), time (8–24 h), and voltage (30–70 V) were... 

A new innovative 'universal' structural joint with multiple applications was devised. The two major conceived contexts for the use of this joint are 'joining beams to columns, ' and 'joining diagonal braces to horizontal ones. ' The main features of this joint are its high rotational capacity, its high shear deformation capacity, its high energy-dissipation capacity, its ability to contain damage, and its repalceability. Due to its geometry, it can well lend itself to protection measures against fire, normally practiced by the involving industries. This makes it a good candidate for being used in structures related to oil and gas industry, offshore or onshore. Through numerical modelling of... 

This review aims to bring together the studies on petroleum reservoirs' sand production control in a comprehensive guide for the researcher to compare various methods for the chemical consolidation of sand. Sand production can be considered one of the major challenges in the petroleum production industry, causing severe operational issues. This study introduces various methods to control and prevent sand production in petroleum wells and evaluates their advantages and performance in tabular form. The use of chemical procedures is considered to be more efficient in counteracting the production and migration of sand. Various chemicals and polymers have been proposed for this purpose. These... 

Steam injection process has been considered for a long time as an effective method to exploit heavy oil resources. Over the last decades, Steam Assisted Gravity Drainage (SAGD) has been proved as one of the best steam injection methods for recovery of unconventional oil resources. Recently, Fast-SAGD, a modification of the SAGD process, makes use of additional single horizontal wells alongside the SAGD well pair to expand the steam chamber laterally. This method uses fewer wells and reduces the operational cost compared to a SAGD operation requiring paired parallel wells one above the other. The efficiency of this new method in naturally fractured reservoir is not well understood.... 

Asphaltene deposition causes serious problems in the oil industry. Variation of oil composition and reservoir pressure is reported to be the most important factors that influence asphaltene deposition from reservoir oil. In this study, a mathematical model was developed to simulate asphaltene deposition during primary depletion and CO2 injection. The main purpose of this study is to investigate and to compare asphaltene deposition mechanisms due to primary depletion and CO2 injection. The solid model as thermodynamic model was applied to investigate asphaltene precipitation. A numerical model was established to the governing equations both in space and time and model parameters were... 

Recently production optimization has gained increasing interest in the petroleum industry. The most computationally expensive part of the production optimization process is the evaluation of the objective function performed by a numerical reservoir simulator. Employing surrogate models (a.k.a. proxy models) as a substitute for the reservoir simulator is proposed for alleviating this high computational cost.In this study, a novel approach for constructing adaptive surrogate models with application in production optimization problem is proposed. A dynamic Artificial Neural Networks (ANNs) is employed as the approximation function while the training is performed using an adaptive sampling... 

Application of solar energy compared to conventional gas-burning boilers for steam generation in thermal Enhanced Oil Recovery processes is a newly attended technology, which brings significant benefits to the petroleum industry through environmental and economical aspects. This technique is especially designed for the regions in which gas-burning steam generation is not viable in large scale. The objective of this study is to investigate about viability of using solar energy to generate steam instead of using conventional steam generators in a Venezuelan extra heavy oil reservoir. Limited gas production policy of the Venezuelan government is the major challenge for utilizing gas steam... 

Recently, a renewed interest arises in the application of nanotechnology for the upstream petroleum industry. In particular, adding nanoparticles to fluids may drastically benefit enhanced oil recovery (EOR) and improve well drilling, by changing the properties of the fluid, rocks wettability alteration, advanced drag reduction, strengthening the sand consolidation, reducing the interfacial tension and increasing the mobility of the capillary trapped oil. In this study, we focus on roles of clay nano-particles on polymer viscosity. Polymer-flooding schemes for recovering residual oil have been in general less than satisfactory due to loss of chemical components by adsorption on reservoir...