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Oil industry suffers from flow assurance problems that occur both in upstream and downstream operations. One of the common flow assurance issues arises from precipitation and deposition of asphaltenes in various locations along the oil production path including near wellbore region in the reservoir, production tubing, flowlines and separation unit at the surface. Asphaltene particles precipitate out of oil continuum due to changes in temperature, pressure or composition. Such changes in operating conditions occur during different recovery processes (natural depletion, gas injection, chemical injection, etc.) as well as production and blending of different oils during transportation. There are different experimental methodologies documented in the literature that describe how to determine onset of asphaltene precipitation. In this paper, a comprehensive review is performed on all the available procedures to measure onset of asphaltene precipitation. The advantages and limitations associated with all these methods are also documented. [ABSTRACT FROM AUTHOR]

Abstract Chemical-assisted waterflooding enhances the ultimate recovery of a conventional waterflooding process through several mechanisms such as reducing interfacial tension between water and oil, formation of in-situ emulsions, treatment of adverse mobility ratio, and wettability modification. Application of chemical-assisted waterflooding for recovery of heavy oil is still an active research topic. A new chemical technology (i.e. IPC Technology as referred to in this paper) has been developed. A proprietary mixture of surfactants is used in several techniques associated with surface extraction as well as in-situ recovery of heavy oil and bitumen. This formulation of solvents and surfactants is reusable, low foaming, non-flammable, not acutely toxic, and non-carcinogenic. The efficacy of using IPC as an additive for waterflooding was presented earlier through a systematic coreflooding study, which showed increased ultimate recovery of different types of oils when compared with commercial surfactant and alkali flooding. In order to investigate the mechanisms behind the enhanced macro-scale oil recovery, a series of pore-scale tests were designed and conducted in this study. Glass micromodel type of porous media was used in the presence of brines with different ion compositions. The pore-scale chemical-assisted waterflooding tests were carried out in four consecutive stages: brine flooding, chemical flooding, soaking period, and extended brine flooding. High quality pore-scale images were captured for qualitative and quantitative analysis of the IPC-assisted waterflooding at the pore-level. IPC intensified water wettability of grain particles in the presence of NaCl; however in the presence of MgCl 2 , use of IPC makes solid surfaces oil-wet. The phenomenon of water-in-oil and oil-in-water emulsification was observed when IPC was used along with different brine compositions. This phenomenon is weakened for lighter oils. When the acid number of the oil was low, extension of soaking period intensified wettability alteration and emulsification mechanisms. Other pore-scale phenomena were also observed during visualization tests such as coalescence of microdroplets during the extended waterflooding stage, snap-off mechanism creating daughter droplets during the extended waterflooding stage, occasional flow of bulk oil films toward the production end, and wettability reversal during various flooding stages. Attempts were also made to conduct statistical analysis of emulsion droplet sizes under different test conditions. Several parameters, including chemical concentration as well as ion concentration in brines, were found to significantly affect the emulsion droplet size distribution. [ABSTRACT FROM AUTHOR]

Abstract Use of chemicals as an additive during steam-based bitumen recovery processes has been an active topic for research and development in the last four decades. In this study, thermo-physical properties of mixtures of bitumen with a newly developed chemical are reported. This new chemical technology (i.e. IPC as referred in this paper) is a proprietary mixture of surfactants that has been used in several techniques associated with surface extraction as well as in-situ recovery of heavy oil and bitumen. This formulation of solvents and surfactants is reusable, low foaming, non-flammable, not acutely toxic and non-carcinogenic. A series of tests were conducted to measure density and viscosity of a bitumen, IPC, and different mixtures of bitumen-IPC at several pressure, temperature and chemical composition conditions. It was observed that solubility of IPC in bitumen was small, and its effects on the oil phase viscosity and density could not be separated from its effects on bulk properties caused by dispersed emulsified droplets of IPC. The impact of IPC on viscosity of mixture was more pronounced than its effect on mixture density. A very complex emulsion was formed upon contact of IPC with bitumen. The results of these tests will be useful in designing a steam-based bitumen recovery process with IPC as the chemical additive. Details of thermal stability analysis of IPC are also presented. Highlights • The effects of IPC formulation on density and viscosity of bitumen-IPC mixtures were studied. • Physical properties and thermal stability of IPC formulation was studied. • IPC formulation had no significant impact on mixture density up to 100 °C. • IPC formulation decreased the mixture viscosity at 100 °C and above. • Complex emulsions were formed upon low temperature mixing of IPC and bitumen. [ABSTRACT FROM AUTHOR]

Although alkaline-surfactant-polymer (ASP) flooding has proven efficient for heavy oil recovery, the displacement mechanisms and efficiency of this process should be discussed further in fractured porous media. In this study, several ASP flooding tests were conducted in fractured glass-etched micromodels with a typical waterflood geometrical configuration, i.e. five-spot injection-production pattern. The ASP flooding tests were conducted at constant injection flow rates but different fracture geometrical characteristics. The ASP solutions consisted of five polymers, two surfactants, and three alkaline types. It was found that using synthetic polymers, especially hydrolyzed polyacrylamide with high molecular mass, as well as cationic surfactant increases the ultimate recovery. The location of the injection well with respect to the fracture system plays a significant role in the ASP flooding performance, i.e. an increase in the angle associated with the longitudinal extension of fractures with respect to the main flow direction resulted in enhanced oil recovery and also postponed the wetting phase breakthrough time. Mechanistic study of this displacement process revealed that dispersive and diffusive behaviour of the ASP front enhanced the fluid transport from fracture to matrix and increased the microscopic displacement efficiency. Emulsification and coalescence mechanisms were responsible for ASP frontal advancement. Residual oil in the invaded region, which was observed in the form of discontinuous oil ganglia dispersed in the invaded pore bodies or in the form of pendular bridges formed around some of the solid particles, was mobilized in the form of oil wads through the droplets of the displacing phase. [ABSTRACT FROM AUTHOR]

Chemical-assisted waterflooding is injection of specialty chemical(s) along with water to enhance the productivity through a series of mechanisms. There are several mechanisms responsible for increased ultimate recovery of such a process compared to the traditional waterflooding process including in-situ emulsification of oil, conformance control and treatment of adverse mobility ratio, reduction of Interfacial Tension (IFT) between the in-situ oil and the injecting phase, and wettability modification to facilitate recovery of oil by enhanced relative permeability values. Although chemical-assisted waterflooding has been applied since the early 20th century, it has not been until recently that applicability of this process has been tested for recovery of heavy oil using preliminary macro-scale as well as pore-scale studies. A new chemical technology (i.e. IPC Technology as referred in this paper) has been developed. A proprietary mixture of surfactants is used in several techniques associated with surface extraction as well as in-situ recovery of heavy oil and bitumen. This formulation of solvents and surfactants is reusable, low foaming, non-flammable, not acutely toxic and non-carcinogenic. A systematic study, based on a series of coreflood tests, was designed and conducted to assess efficacy of IPC in the ultimate recovery of different types of oils by use of IPC-assisted waterflooding. Effects of IPC on IFT between oil and IPC solutions at different brine salinities/hardnesses and IPC concentrations were determined. Compatibility of IPC with different brine hardnesses and salinities was determined. IPC technology was particularly effective in recovering heavy oil. The performance of IPC as an additive during waterflood at elevated temperature for recovery of heavy oil was also investigated. For this particular purpose, thermal stability tests were conducted to determine the threshold temperature below which the formulation is thermally stable. When production performance of IPC-assisted waterflood was compared with alkali flooding and a commercial surfactant, IPC gave superior ultimate recovery. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • This study introduces an experimental and modeling approach to obtain asphaltene precipitation. • The new technique is more accurate for light to heavy oils, compared to previous models. • The new approach considers vital oil and process characteristics in asphaltene precipitation. • A sensitivity analysis is conducted to make better operating and policy decisions while dealing with asphaltene precipitation. • The most influencing parameters in asphaltene precipitation are pressure and dilution ratio. Abstract Asphaltenes are heavy fractions of petroleum mixtures, which precipitate out of homogenous bulk fluid phase due to changes in pressure, temperature, and composition. Asphaltene precipitation and subsequent deposition in porous media can adversely affect Enhanced Oil Recovery (EOR) processes as well as impede surface transportation of crude oil. It is therefore beneficial to develop accurate techniques for determination of asphaltene precipitation as well as reliable predictive modeling approaches to remedy potential production impairments. In this study, a laboratory work is performed using three different oil samples (light, medium-viscosity, and heavy crude oil) to measure the mass of precipitated asphaltenes in a series of titration experiments. The effects of various parameters such as precipitant type, pressure, dilution ratio, API gravity of oil, and resin-to-asphaltene ratio of crude oil on the amount of precipitated asphaltenes are studied. A deterministic tool, so-called Response Surface Methodology (RSM), is then proposed to estimate the mass of asphaltenes precipitated from these three oil types in a titration process as a function of input parameters selected through a systematic parametric sensitivity analysis. The Analysis of Variance (ANOVA) technique is also employed to assess the validity of the proposed predictive methodology. Among all the contributing parameters, pressure and dilution ratio are found to be the most influencing factors when predicting the mass of precipitated asphaltenes. The developed simple predictive tool appears to be an effective methodology to forecast the mass of precipitated asphaltenes over a wide range of input parameters for various oil types. [ABSTRACT FROM AUTHOR]