Sharif Digital Repository

Many reservoir and production engineers face asphaltene precipitation as a major problem during miscible carbon dioxide flooding projects. Experimental studies regarding asphaltene precipitation are therefore employed to assist in selecting appropriate facilities and proper operation schemes. During this study, a series of high pressure, high temperature experiments are designed and performed to analyze asphaltene precipitation behavior of an Iranian light reservoir crude at reservoir conditions due to natural production and miscible CO2 gas injection. For both sets of experiments, two different temperature levels (including reservoir temperature) are selected to investigate the role of... 

Hydrocarbon production decline as a result of formation damage caused by fines migration has been widely observed in laboratory corefloods and natural flows in porous media. Permeability impairment due to fines migration is explained by different capture mechanisms of already released particles at some pore sites. Preventing detachment of in-situ particles from the rock surface during enhanced oil recovery (EOR) agent injection into the porous media has been reported recently. In this experimental study, the effect of five types of metal oxide nanoparticles; γ-AI2O3, ZnO, CuO, MgO and SiO: to adsorb the fine particles existing in the flowing suspension has been investigated. In each test,... 

Experimental Investigation of the Asphaltene Deposition Process during Different Production Schemes - This paper presents the results of asphaltene precipitation and deposition during lean gas injection, CO2 injection and natural depletion in reservoir conditions. In addition, the effect of variations in operating pressure, injection gas concentration and production rate on asphaltene precipitation and deposition were investigated. The severity of asphaltene deposition was found to be more pronounced in lean gas injection in comparison with CO2 injection and natural depletion. Increasing the flow rate in natural depletion xperiments showed a considerable increase in asphaltene deposition,... 

In the optimization of naturally fractured reservoirs, it is required to take into account their complex flow behavior due to high conductivity fractures. In this regard, the possible effects of fractures must be included in the optimization procedure. In a water-flooding project, fast water breakthrough from injection to production wells may be occurred because of high permeability fractures. To consider the effect of the fracture system, a multi-criterion optimization procedure is proposed in this work. For this contribution, Non-dominated Sorting Genetic Algorithm version II (NSGA-II) is implemented for the optimization purposes. Considering the effect of the fracture system on the flow... 

The concern over fossil energy shortage for the next decade leads to the extensive research activities in the area of enhanced oil recovery. Steam injection as one of well known EOR process has been used for about five decades to improve the oil production rate and recovery efficiency. Steam flooding is applied to heavy and extra-heavy oil reservoirs; however it could be used in light oil reservoirs in which water injection do not work effectively. Regardless of different performances, this method is an efficient EOR process for both heavy and light oil reservoirs. In this work, two separate numerical models were prepared to investigate steam flooding performance for the recovery of light... 

In this paper, different injectivity scenarios were experimentally investigated in a coreflooding system to observe the efficiency of each method in laboratory conditions. Surfactant flooding, CO2 injection, carbonated water injection (CWI), active carbonated water injection (ACWI), after water flooding were investigated through the coreflooding system. First, it is necessary to optimize the surfactant concentration and then use it in ACWI injection. To do this, linear alkylbenzene sulfonic acid (LABSA) was used as a cationic surfactant at different concentrations. It was observed that 0.6 PV concentration of LABSA had an optimum result as increasing the surfactant concentration would not be... 

Decision on the location of new wells through infill drilling projects is a complex problem that depends on the reservoir rock and fluid properties, well and surface facilities specifications, and economic measures. Conventional approach to address this is a direct optimization that uses the numerical flow simulation. However, this is computationally very extensive. In this study the authors use a hybrid genetic algorithm (HGA) optimization technique based on the genetic algorithm (GA) with helper functions based on the polytope algorithm and the neural network. This hybridization introduces hill-climbing into the stochastic search and makes use of proxies created and calibrated iteratively... 

Decision on the location of new wells through infill drilling projects is a complex problem that depends on the reservoir rock and fluid properties, well and surface facilities specifications, and economic measures. Conventional approach to address this is a direct optimization that uses the numerical flow simulation. However, this is computationally very extensive. In this study the authors use a hybrid genetic algorithm (HGA) optimization technique based on the genetic algorithm (GA) with helper functions based on the polytope algorithm and the neural network. This hybridization introduces hill-climbing into the stochastic search and makes use of proxies created and calibrated iteratively... 

Smart water flooding as a developing technique utilizes modified water chemistry in terms of salinity and composition to prepare the best-suited brine composition for a specific brine/oil/rock system to obtain higher oil recovery efficiency. Huge amount of unrecovered oil is expected to be remained in carbonate reservoirs; however, few research works on incremental oil recovery during smart water injection in carbonate cores at reservoir condition are reported. Several core flooding tests using one of the Iranian carbonate reservoir rock are conducted to check the effectiveness of smart water injection for more oil recovery efficiency. The results reaffirm the positive effect of sulfate ions... 

In this study, the main recovery mechanisms behind oil/water/gas interactions during the water-alternating-gas (WAG) injection process, in a network of matrix/fracture, were fundamentally investigated. A visual micromodel was utilized to provide insights into the potential applications of WAG process in fractured oil-wet media as well as the possibility of observing microscopic displacement behavior of fluids in the model. The model was made of an oil-wet facture/matrix network system, comprised of four matrix blocks surrounded with fractures. Different WAG injection scenarios, such as slug arrangements and the effects of fluid injection rates on oil recovery were studied. A new equation... 

Porous medium characteristics (e.g., pore geometry and medium heterogeneity) as well as the chemical nature of the co-solvents crucially affect the oil displacement efficiency during solvent flooding processes. In this work, initially saturated models with heavy crude oil were used to perform a series of solvent injection experiments. Several onequarter five-spot micromodels with pre-designed pore geometry were constructed and used. In addition, rock-look-alike flow patterns generated from thin sections of sandstone and dolomite reservoir rocks were etched onto glass plates to form micromodels mimicking the pore geometry and heterogeneity of these rocks. Four different groups of chemicals... 

This study concerns with the microscopic and macroscopic fluid distribution and flow behavior during water alternating solvent (WAS) injection process to heavy oil using micromodel generated from thin section of a real rock which has rarely attended in the available literature. In this study, a one-quarter five-spot glass micromodel was deployed to examine the effect of flow media topology on microscopic displacements as well as macroscopic efficiency of WAS process. The micromodel was initially saturated with the heavy oil, and then the hydrocarbon solvent and water were injected alternately into it. The observations confirmed that WAS injection scheme is an effective method for the... 

The main issue in heavy oils enhanced recovery methods is to reduce their viscosity in order to get a better mobility. This is commonly obtained by blending the oil with light hydrocarbons. Co-solvents are good candidates to improve the hydrocarbon recovery efficiency especially in miscible processes. However, the effect of co-solvents on miscible flooding of heavy oil reservoirs at different pore geometries is not well understood. In this work different one-quarter five-spot network patterns along with those generated from reservoir rocks' thin sections were etches on glass surfaces. The models that had been initially saturated with the heavy crude oil were used to perform a series 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... 

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... 

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... 

Condensate and water banking around gas condensate wells result in vital well deliverability issues. Wettability alteration of near wellbore region to gas wetting condition is known to be the most novel and the only permanent method, to improve condensate well productivity. In this work, a water based nanofluid is used to change the wettability of sandstone reservoir rocks from strongly liquid wetting to intermediate gas wetting condition. Static contact angle measurements demonstrated significant increase of liquid phase contact angle as a result of chemical treatment with SurfaPore M nanofluid. The characteristics of SurfaPore M adsorption on sandstone rock are quantified through kinetic... 

In this work, a series of solvent- and water-injection scenarios were conducted on horizontal five-spot glass micromodels that were saturated initially with heavy oil. Sandstone and limestone rock look-alike and network patterns with different pore structures were used in the experiments. The results show that the ultimate oil recovery of a water-alternating-solvent (WAS) scheme was greater than that of a simultaneously water-alternating-solvent (SWAS) scheme, and the efficiency of a solvent-soak scheme also offers a greater recovery. Likewise, the WAS scheme resulted in greater oil recovery when compared with continuous solvent injection (CSI), with the same amount of solvent consumption.... 

This work is concerned with the role of geometrical properties of fractures on oil displacement efficiency during solvent injection to heavy oil. Here, a series of solvent injection processes were conducted on one-quarter five-spot fractured micromodels that were initially saturated with the heavy oil, at a fixed flow rate condition. The oil recovery was measured using image analysis of the continuously provided pictures. The results show that for the range of experiments performed here, the maximum oil recovery happens at a fracture orientation angle of 45 degrees. Also, increasing the number of fractures leads to a higher oil recovery factor by solvent in 45 degrees, while it does not... 

In this work a series of solvent injection experiments was conducted on horizontal glass micromodels at several fixed flow rate conditions. The micromodels were initially saturated with heavy crude oil. The produced oil as a function of injected volume of solvents was measured using image analysis of the continuously provided pictures. In order to investigate the macroscopic behavior of the process in different media, several fractured, with constant width, and nonfractured five-spot micromodels were designed and used. The measured data have also been used for verifying and developing a simulation model that was later used for sensitivity analysis of some parameters that affect oil recovery....