Sharif Digital Repository

Steam-assisted gravity drainage is one of the most promising strategies to develop huge heavy oil and bitumen accumulations. Like the other thermal processes, this method aims at reducing oil viscosity by increasing the temperature. But in an economical point of view, it requires a great volume of steam for injection. Moreover, early breakthrough of steam and high steam-oil ratio makes it uneconomical, especially in long production time. In this study, a new method, two wells cyclical steam-assisted gravity drainage is compared with a conventional steam-assisted gravity drainage process. Well configuration in two wells cyclical steam-assisted gravity drainage is the same as the... 

In this work, the vapour extraction (VAPEX) process is studied experimentally in a rectangular physical model at moderate-high pressure. The solvent was either pure propane or a mixture of propane/ methane with different compositions. The solvent and carrier gas were totally mixed before injection, so that a solvent with the desired composition flowed through the injector during experiments, and the solvent mixture was in thermodynamic equilibrium before injection into VAPEX cell. Effects of pressure and composition of solvent were studied. Results showed that at a fixed pressure, the process is more effective with pure solvent compared to the use of solvent mixtures. The main feature of... 

Almost all of the heavy oil reservoirs contain discontinuous permeability barriers (shales) with different structures. However, the effect of shaly layer geometrical characteristics including: spacing from wells, discontinuity, orientation, shaly layers' spacing and length, and heterogeneous distribution on oil recovery factor in the presence of gravity force are not well understood. In this work, a series of solvent injection experiments were conducted on various vertical one-quarter five-spot glass micromodels, containing barriers, which were initially saturated with a heavy oil sample. The oil recovery was measured by analysis of the pictures provided continuously during the injection... 

In the upstream asphaltene flow assurance community, both academics and industries are actively involved to predict the asphaltene deposit profile in wellbores and pipelines. Essential information for such a study is the amount of asphaltenes that can precipitate and, hence, deposit. In this work, the perturbed chain form of the statistical associating fluid theory (PC-SAFT) is applied to predict the asphaltene precipitation onset condition as well as the amount of precipitate under pressure depletion and high-pressure and high-temperature gas injection conditions. Previous PC-SAFT asphaltene studies in crude oil required the compositional data for both flashed gas and flashed liquid. This... 

The increasing incidence of flow assurance problems caused by asphaltene deposition during oil production has motivated the development of numerous theoretical models and experimental methods to analyze this complex phenomenon. Even more challenging are the prediction of the occurrence and the magnitude of asphaltene deposition. It is well accepted that precipitation of asphaltene is a necessary condition for deposition. Hence, a significant amount of work has been devoted to the understanding of the conditions at which asphaltene precipitate from the crude oil. Although, several models seem to work well for correlating available data of onsets of asphaltene precipitation, they usually lack... 

This paper concerns on experimental investigation of biopolymer/polymer flooding in fractured five-spot systems. In this study, a series of polymer injection processes were performed on five-spot glass type micromodels saturated with heavy crude oil. Seven fractured glass type micromodels were used to illustrate the effects of polymer type/concentration on oil recovery efficiency in presence of fractures with different geometrical properties (i.e., fractures orientation, length and number of fractures). Four synthetic polymers as well as a biopolymer at different levels of concentration were tested. Also a micromodel constituted from dead-end pores with various geometrical properties was... 

The Conventional Fire Flooding (CFF) process application feasibility on fractured carbonated reservoirs remained questionable. In this paper first combustion parameters and reaction kinetics of a naturally fractured low permeability carbonated heavy oil reservoir in Iran called Kuh-E-Mond applied to simulation study. After that, simulator has been validated with Kuh-E-Mond combustion tube experiment. Recovery mechanism in single block matrix is different from one in conventional model since oxygen first flows into the fractures and then diffuses from all sides into the matrix. Combustion of the oil in the fractures produces some water ahead of fracture combustion front which prohibits oxygen... 

Although viability of low-salinity waterflooding (LSWF) at the laboratory scale has been proven, there are some challenges associated with its field application, which sheds uncertainties on its economic success. One of the challenges is the minimum required volume of low-salinity water, which should be injected to the reservoir due to the salt dispersion in porous media. Once the low-saline brine is injected into the reservoir, mixing of injected (low-salinity) and resident (high-salinity) brines occurs and the developed mixing zone grows continuously as the front moves from the injection well toward the production well. Increase in the salinity of the front reduces the efficiency of LSWF.... 

Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of... 

Alkalis, surfactants and/or polymers are usually injected in the injector wells so that the injection fluids can sweep through the reservoir and mobilize/recover more oil. However, the formation of stable emulsion due to the residual chemicals in the recovered crude oil poses problems in the primary separation process. This study focuses on the effect of Alkali-Surfactant-Polymer injection on creaming and coalescence of crude oil and water emulsion produced in the primary gravity separator. In addition, a model is developed in this work to predict the separation effectiveness of oil and water emulsion containing ASP. In this work, the effect of ASP on the stability and the separation of... 

Thermodynamic modeling is known as a promising tool for phase behavior modeling of asphaltene precipitation under different conditions such as pressure depletion and CO2 injection. In this work, a thermodynamic approach is used for modeling the phase behavior of asphaltene precipitation. The precipitated asphaltene phase is represented by an improved solid model, while the oil and gas phases are modeled with an equation of state. The PR-EOS was used to perform flash calculations. Then, the onset point and the amount of precipitated asphaltene were predicted. A computer code based on an improved solid model has been developed and used for predicting asphaltene precipitation data for one of... 

There are different thermodynamic models that have been applied for modelling of asphaltene precipitation caused by various reasons, such as solvent/CO2 injection and pressure depletion. In this work, two computer codes based on two different asphaltene precipitation thermodynamic models-the first being the thermodynamic micellization model with a different characterization approach and the second being the solid model-have been developed and used for predicting asphaltene precipitation data reported in the literature as well as in the obtained data for Sarvak reservoir crude, which is one of the most potentially problematic Iranian heavy oil reserves under gas injection conditions. For the... 

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.... 

As the oil production from conventional oil reservoirs is decreasing, oil production through Enhanced Oil Recovery (EOR) processes is supposed to compensate for both the oil production reduction in matured oil reservoirs and the worldwide dramatic increase in oil demand. Therefore, developing a strategy to choose an optimized EOR technique is crucial to find a resolution for production decline in oil reservoirs. A screening tool recommending the most appropriate EOR method is proposed in this study. An expert fuzzy logic system is employed to screen four well-known EOR methods including miscible CO2 injection, miscible HC gas injection, polymer flooding and steam injection based on the... 

Thermodynamic modeling is known as a promising tool for phase behavior modeling of asphaltene precipitation under different conditions such as pressure depletion and CO2 injection. In this work, a thermodynamic approach is used for modeling the phase behavior of asphaltene precipitation. The precipitated asphaltene phase is represented by an improved solid model, while the oil and gas phases are modeled with an equation of state. The PR-EOS was used to perform flash calculations. Then, the onset point and the amount of precipitated asphaltene were predicted. A computer code based on an improved solid model has been developed and used for predicting asphaltene precipitation data for one of... 

Although alkaline-surfactant-polymer flooding is proved to be efficient for oil recovery from heavy oil reservoirs, the displacements mechanism/efficiency of this process in fractured systems needs to more discussion, especially in five-spot patterns. In this work, several ASP flooding test were performed on fractured micromodels which were initially saturated with heavy oil at constant flow rate and different fracture geometrical characteristics conditions. The ASP solutions are constituted from 5 polymers i.e. four synthetic polymers include three hydrolyzed polyacrylamide with different molecular weight as well as a non-hydrolyzed polyacrylamide and a biopolymer, 2 surfactants i.e. a... 

In this work effect of composition changes of injection gas, CH4 + CO2, on the performance of immiscible WAG injection in light oil, 41 oAPI, which has been rarely attended in the available literature is investigated. Presence of CO2 helps to reduce the MMP of CH4 significantly. Core flood experiments are conducted at reservoir conditions and fixed flow rate of 0.5cc/min on a sandstone sample with the brine concentration of 5000 ppm, and the influence of injection gas composition as well as WAG ratio on oil recovery is investigated. Different mole percents of methane in mixture, 0%, to 100% are examined, and the tests continued to ten alternate cycles with a slug size of 0.1 pore volumes and... 

This work examines the operational parameters that may influence the performance of toe-to-heel steamflooding in a laboratory-scale simulation model built on the basis of the fluid and rock samples from a fractured, low-permeable, carbonate heavy oil reservoir in Southwestern Iran, called KEM (Kuh-e-Mond). Using vertical (V) or horizontal (H) injectors (I) and producers (P), the effects of different well configurations including VIVP, VIHP, 2VIHP, VI2HP, HIHP, and HI2HP, injectors' traversal distance, producers' traversal distance, and horizontal producer length have been investigated. In summary, the results show that 2VIHP scheme performs best in terms of oil recovery and areal/volumetric... 

There are different thermodynamic models that have been applied for modelling of asphaltene precipitation caused by various reasons, such as solvent/CO2 injection and pressure depletion. In this work, two computer codes based on two different asphaltene precipitation thermodynamic models-the first being the thermodynamic micellization model with a different characterization approach and the second being the solid model-have been developed and used for predicting asphaltene precipitation data reported in the literature as well as in the obtained data for Sarvak reservoir crude, which is one of the most potentially problematic Iranian heavy oil reserves under gas injection conditions. For the... 

Nitrogen has been appeared as a competitive gas injection alternative for gas-based enhanced oil recovery (EOR) processes. Minimum miscibility pressure (MMP) is the most important parameter to successfully design N2 flooding, which is traditionally measured through time consuming, expensive and cumbersome experiments. In this communication, genetic programming (GP) and constrained multivariable search methods have been combined to create a simple correlation for accurate determination of the MMP of N2-crude oil, based on the explicit functionality of reservoir temperature as well as thermodynamic properties of crude oil and injection gas. The parameters of the developed...