Experimental Study of Compositional Factor on Asphaltene Deposition for Heavy Crude Oil Dilution in Offshore Production and Transportation

2016 ◽  
Author(s):  
Jiaqiang Jing ◽  
Cheng Wu ◽  
Xiaoshuang Chen ◽  
Junwen Chen ◽  
Ping Lu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Heavy Oil ◽  
High Efficiency ◽  
Carbon Number ◽  
Prediction Method ◽  
Wire Mesh ◽  
Asphaltene Precipitation ◽  
Onset Point ◽  
Asphaltene Deposition ◽  
Light Oil

Heavy oil dilution has been widely used in the oil production and transportation due to its high efficiency in viscosity and drag reduction, and great convenience in operation. The composition of the heavy oil will change while being mixed with some diluents, thus the stability of the asphaltene in the heavy oil might be destroyed, which leads to a tremendous threat to the safe and economic operation of the production and transportation system. The asphaltene contents of eight onshore and offshore oil samples were measured using n-heptane and toluene, then the asphaltene deposition onset points of the oils diluted with n-alkanes (n-C7) were evaluated using viscosity methods. The reliability of the asphaltene deposition predicted by the refractive index of the diluted oils was verified, and meanwhile the impacts of n-C5, n-C7 and n-C8 on the asphaltene precipitation behavior were measured and analyzed. And then the status of the asphaltene deposition, suspending particle distribution and adhesion of the heavy oil diluted with diesel in the stainless wire mesh located in the visible loop pipe layout was investigated. The studied results demonstrate that the asphaltene deposition onset point has no direct relation to its content, and those of the eight diluted oils ranged from 15% to 30% at 70 °C. The onset point prediction method was verified to be reliable because it is based on that the critical solubility parameter and the square root of the diluent molar volume in the Asphaltene-Instability-Trend (ASIST) curve present a good linear relation. The relationship between the refractive index of the diluted oil and its asphaltene deposition onset point depends on the light oil type, and the smaller its carbon number, the more serious the asphaltene deposition in its diluted oil. The reasonable amount of a light oil blended with a heavy oil should well consider the light oil source, its economy and the asphaltene deposition risk at the same time.

Optimal Application Conditions of Solvent Injection Into Oil Sands To Minimize the Effect of Asphaltene Deposition: An Experimental Investigation

2014 ◽  
Vol 17 (04) ◽  
pp. 530-546 ◽  
Author(s):  
L.. Moreno-Arciniegas ◽  
T.. Babadagli
Keyword(s):  
Heavy Oil ◽  
Glass Bead ◽  
Carbon Number ◽  
Operating Conditions ◽  
Viscosity Reduction ◽  
Solvent Injection ◽  
Hydrocarbon Solvents ◽  
Solvent Type ◽  
Asphaltene Deposition ◽  
Pore Plugging

Summary Solvent injection into heavy-oil reservoirs is quite complex because of the asphaltene destabilization that occurs because of the changes in temperature, pressure, and solvent type dissolved in oil. As a result of this destabilization, the asphaltene flocculates, agglomerates, and eventually plugs the pores in the reservoir because of the formation of asphaltene clusters. In solvent applications, light-molecular-weight hydrocarbon solvents are preferred because of their high diffusion coefficient; however, as the carbon number of n-alkane solvents decreases, asphaltene precipitation increases. Therefore, the selection of the solvent and application condition is highly critical in cold and thermally aided solvent applications. In this research, low-carbon-number n-alkane (propane, n-hexane, and n-decane) and a distillate-hydrocarbon (obtained from a heavy-oil-upgrading facility) injection into glass-bead-pack systems saturated with heavy oil (87,651 and 20,918 cp at 25°C) were evaluated at different pressure conditions that are applicable to typical Canadian oil-sand reservoirs (698–2068 kPa) and temperatures (25–120°C). First, the asphaltene behavior of different solvents at different pressures and temperatures was studied through deasphalting work in a pressure/volume/temperature (PVT) cell in previous work [Moreno and Babadagli (2013)]. By use of quantitative (amount of asphaltene precipitated) and qualitative (microscopic images of asphaltene clusters) observations, asphaltenes were classified in terms of their shape, size, and quantity for different oil/solvent types, pressure, and temperature. Continually, the same n-alkane, distillate-hydrocarbon solvents, and heavy oil were used in gravity-stable-displacement glass-bead-pack experiments. 3-D (cylindrical) glass-bead-pack experiments were carried out at the same temperature and pressure conditions used for the PVT experiments. The operational conditions, oil composition, and solvent type showed significant effects on oil-recovery factor. Asphaltene deposition and residual oil saturation (ROS) in the glass-bead pack and the amount of asphaltene in the produced oil were measured, and the standard saturate, aromatic, resin, and asphaltene (SARA) analysis was applied to determine the optimal operating conditions yielding the highest recoveries with minimal pore plugging. Moreover, the pore-plugging process was analyzed through a visual scanning electron microscope (SEM) and optical microscope to find the different organic deposition formation and agglomeration. Oil production was evaluated by use of microscope visualization, viscosity reduction, and refractive-index values. Eventually, optimal application conditions for solvent and thermally aided solvent injection were listed for a wide range of heavy-oil and solvent types.

An Approach for Characterization and Lumping of Plus Fractions of Heavy Oil

2010 ◽  
Vol 13 (02) ◽  
pp. 283-295 ◽  
Author(s):  
I.. Rodriguez ◽  
A.A.. A. Hamouda
Keyword(s):  
Molecular Weight ◽  
Mole Fraction ◽  
Heavy Oil ◽  
Equations Of State ◽  
Carbon Number ◽  
Compositional Analysis ◽  
Volume Depletion ◽  
Molecular Weights ◽  
Pvt Data ◽  
Light Oil

Summary Heavy-oil fluids contain large concentrations of high-molecular-weight components, including a large content of the plus fractions, such as C7+. Different approaches have been developed to characterize the petroleum plus fractions to improve prediction of the pseudocomponents properties by equations of state (EOSs). A method is developed in this work to split the plus fraction into single carbon numbers (SCN), generating the mole fraction and the respective molecular weight. The developed method is based on the relationships between three-parameter gamma (TPG) distribution, experimental mole fraction, molecular weight, and SCN data obtained from the literature and industrial contacts. TPG is used to fit the trend of the compositional analysis. The characterized mole distribution as a function of SCNs is generated by integrating the TPG between the limiting molecular weights (LMw). The limiting molecular weights are determined simultaneously during the integration process by fitting the characterized and experimental mole fractions. The developed method is easy to use. In addition, the approach is not dependent on the assumption that only normal carbon numbers exist in the composition resulting on fixed molecular weights for each single carbon number. There are several correlations generated to predict physicochemical properties as a function of SCNs. Those correlations have been originally developed to work with light oil. Our approach is combined with some of the correlations and is tested for heavy-oil samples to identify the ranges in which they can be applied. Two lumping schemes are used to group the SCNs into pseudocomponents. The properties for each pseudo-component in this work are used to predict pressure/volume/temperature (PVT) data, constant volume depletion, using the Peng-Robinson EOS (PR-EOS), and the PVTP™ commercial simulator.

Mechanics of Heavy-Oil and Bitumen Recovery by Hot Solvent Injection

2012 ◽  
Vol 15 (02) ◽  
pp. 182-194 ◽  
Author(s):  
V.. Pathak ◽  
T.. Babadagli ◽  
N.R.. R. Edmunds
Keyword(s):  
Oil Recovery ◽  
Heavy Oil ◽  
Numerical Models ◽  
Optimum Operating ◽  
Asphaltene Precipitation ◽  
Optimum Operating Temperature ◽  
Asphaltene Deposition ◽  
Temperature And Pressure ◽  
Bitumen Recovery ◽  
Visualization Experiments

Summary In earlier work (Pathak et al. 2010, 2011), we presented the initial results for heavy-oil and bitumen recovery using heated solvent vapors. The heavy-oil- and bitumen-saturated sandpack samples of different heights were exposed to heated vapors of butane or propane at a constant temperature and pressure for an extended duration of time. The produced oil was analyzed for recovery, asphaltene content, viscosity, composition, and refractive index. Recovery was found to be very sensitive to temperature and pressure. The current work was undertaken to better understand the physics of the process and to explain the observations of the earlier experiments using additional experiments on tighter samples of different sizes, numerical simulation, and visualization experiments. The effects of temperature and pressure on the recovery were studied using a commercial reservoir simulator. Propane and butane were used as solvents. Asphaltene precipitation was also modeled. A qualitative history match with the experiments on different porous-media types was achieved by mainly considering the permeability reduction caused by asphaltene precipitation; pore plugging; the extent of interaction between the solvent and oil phases; and parameters such as model height, vertical permeability, and gravity. The effect of asphaltene deposition on models of varying permeabilities was also studied. To investigate the phenomenon further, visualization experiments were performed. 2D Hele-Shaw models of different dimensions were constructed by joining two Plexiglass sheets from three sides, or in some experiments, from all sides. The models were saturated with heavy oil and left open on one side (or all sides) and were exposed to different types of solvents. The setup was monitored continuously to observe fluid fronts and asphaltene precipitation. By use of this analysis, the mechanics of the process was clarified from the effect of solvent type on the recovery process. The optimum operating temperature for the hot-solvent process and the dominant mechanisms were identified. The dynamics of the asphaltene deposition and its effect on oil recovery were clarified through visual and numerical models.

Aerodynamic Characterization of Transonic Turbine Vanes Optimized to Attenuate Rotor Forcing

2011 ◽  
Author(s):  
R. Puente ◽  
G. Paniagua ◽  
T. Verstraete
Keyword(s):  
High Efficiency ◽  
Prediction Method ◽  
Optimization Procedure ◽  
3D Design ◽  
Turbine Vanes ◽  
Turbine Vane ◽  
Loss Prediction ◽  
Transonic Turbine ◽  
Characteristic Features

A multi-objective optimization procedure is applied to the 3D design of a transonic turbine vane row, considering efficiency and stator outlet pressure distortion, which is directly related to induced rotor forcing. The characteristic features that define different individuals along the Pareto Front are described, analyzing the differences between high efficiency airfoils and low interaction. Pressure distortion is assessed by means of a model that requires only of the computation the steady flow field in the domain of the stator. The reduction of aerodynamic rotor forcing is checked via unsteady multistage aerodynamic computations. A well known loss prediction method is used to drive the efficiency of one optimization run, while CFD analysis is used for another, in order to assess the reliability of both methods. In both cases, the decomposition of total losses is performed to quantify the influence on efficiency of reducing rotor forcing. Results show that when striving for efficiency, the rotor is affected by few, but intense shocks. On the other hand, when the objective is the minimization of distortion, multiple shocks will appear.

Compatibility Study of Condensate and Heavy Oil for Storage in an Iranian Reservoir

2021 ◽  
pp. 1-13
Author(s):  
K. Zobeidi ◽  
M. Ganjeh-Ghazvini ◽  
V. Hematfar
Keyword(s):  
Heavy Oil ◽  
Oil And Gas ◽  
Production Performance ◽  
Compatibility Study ◽  
Asphaltene Precipitation ◽  
High Concentration ◽  
Full Capacity ◽  
Potential Risks ◽  
Operational Criteria ◽  
Positive Effect

Summary During the years 2017–2020, when Iran faced restrictions on the sale of oil and gas condensate and due to the need for domestic consumption and gas sales commitments, it was inevitable to produce gas at full capacity. This coercion has led to significant production of gas condensates. Some of these condensates were sold, some were converted into products such as gasoline in domestic refineries, and some of these condensates needed to be stored, but the storage capacity was limited. For the purpose of underground condensate storage, a heavy oil reservoir was selected based on some technical and operational criteria. A feasibility study was conducted to evaluate the potential risks of condensate injection into the reservoir. The results of tests on asphaltene precipitation, as the most important risk, indicated no severe precipitation would occur even if high concentration of condensate mixed with the reservoir heavy oil. The recovery of condensate and the production performance of the reservoir were simulated in three different injection-production scenarios. The results showed a positive effect of condensate injection on production rate of the reservoir. Moreover, satisfactory volume of condensate could be recovered in a reasonable period of time.

Effective Removal of Asphaltene Deposition in Metal-Capillary Tubes

SPE Journal ◽  
2016 ◽  
Vol 21 (05) ◽  
pp. 1747-1754 ◽  
Author(s):  
Sara M. Hashmi ◽  
Abbas Firoozabadi
Keyword(s):  
Organic Acid ◽  
Laboratory Scale ◽  
Asphaltene Precipitation ◽  
Aromatic Solvent ◽  
Benzene Sulfonic Acid ◽  
Chemical Treatments ◽  
Effective Removal ◽  
Dodecyl Benzene Sulfonic Acid ◽  
Asphaltene Deposition ◽  
Petroleum Fluid

Summary We describe asphaltene deposition and removal processes in metal capillaries. We induce asphaltene precipitation by adding an asphaltene precipitant, heptane, to a petroleum fluid. The mixture is then injected through a laboratory-scale capillary and allowed to deposit. We assess the reversal of the deposition by means of the use of two separate chemical treatments: (1) a strong organic acid surfactant and (2) an aromatic solvent. The strong organic acid surfactant, dodecyl benzene sulfonic acid (DBSA), was shown to completely dissolve asphaltenes by means of acid-base chemistry reactions at heteroatomic sites on the asphaltene molecules. We investigate the use of DBSA as an efficient removal agent, injecting it in a mixture of petroleum fluid after the deposit was already formed. An aromatic solvent, toluene, is also investigated in such a fashion to assess its ability in removing deposited asphaltenes. We find that DBSA can effectively remove asphaltene deposits within one pore-volume (PV) of injection and at concentrations roughly ten times less than that required by an aromatic solvent such as toluene. To the best of our knowledge, our current study is the first laboratory-scale investigation with surfactant chemicals to reverse asphaltene deposition in capillaries.

scholarly journals Research on heavy oil gas lift assisted with light oil injected from the annulus

2018 ◽  
Vol 8 (4) ◽  
pp. 1465-1471 ◽  
Author(s):  
H. Q. Zhong ◽  
S. Zhu ◽  
W. G. Zeng ◽  
X. L. Wang ◽  
F. Zhang
Keyword(s):  
Heavy Oil ◽  
Light Oil ◽  
Oil Gas ◽  
Gas Lift

Laboratory Investigation of Permeability Impairment Caused by Asphaltene Precipitation during Screening for Gas-Injection Enhanced Oil Recovery and Pressure Change in a Major Gulf of Mexico Field

SPE Journal ◽  
2021 ◽  
pp. 1-21
Author(s):  
M. R. Fassihi ◽  
E. Turek ◽  
M. Matt Honarpour ◽  
D. Peck ◽  
R. Fyfe
Keyword(s):  
Gulf Of Mexico ◽  
Gas Injection ◽  
Rock Surface ◽  
Permeability Reduction ◽  
Test Results ◽  
Asphaltene Precipitation ◽  
The Core ◽  
Asphaltene Deposition ◽  
Core Permeability ◽  
Permeability Impairment

Summary As part of studying miscible gas injection (GI) in a major field within the Green Canyon protraction area in the Gulf of Mexico (GOM), asphaltene-formation risk was identified as a key factor affecting a potential GI project. The industry has not conducted many experiments to quantify the effect of asphaltenes on reservoir and well performance under GI conditions. In this paper we discuss a novel laboratory test for evaluating the asphaltene effect on permeability. The goals of the study were to define the asphaltene-precipitation envelope using blends of reservoir fluid and injection gas, and measure permeability reduction caused by asphaltene precipitation in a core under GI. To properly analyze the effect of GI, a suite of fluid-characterization studies was conducted, including restored-oil samples, compositional analysis, constant composition expansion (CCE), and differential vaporization. Miscibility conditions were defined through slimtube-displacement tests. Gas solubility was determined through swelling tests complemented by asphaltene-onset-pressure (AOP) testing. The unique procedure was developed to estimate the effect of asphaltene deposition on core permeability. The 1-ft-long core was saturated with the live-oil and GI mixture at a pressure greater than the AOP, and then pressure was depleted to a pressure slightly greater than the bubblepoint. Several cycles of charging and depletion were conducted to mimic continuous flow of oil along the path of injected gas and thereby to observe the accumulation of asphaltene on the rock surface. The test results indicated that during this cyclic asphaltene-deposition process, the core permeability to the live mixture decreased in the first few cycles but appeared to stabilize after Cycle 5. The deposited asphaltenes were analyzed further through environmental scanning electron microscopy (ESEM), and their deposition was confirmed by mass balance before and after the tests. Finally, a relationship was established between permeability reduction and asphaltene precipitation. The results from the asphaltene-deposition experiment show that for the sample, fluids, and conditions used, permeability is impaired as asphaltene flocculates and begins to coat the grain surfaces. This impairment reaches a plateau at approximately 40% of the initial permeability. Distribution of asphaltene along the core was measured at the end by segmenting the core and conducting solvent extraction on each segment. Our recommendation is numerical modeling of these test results and using this model to forecast the magnitude of the permeability impairment in a reservoir setting during miscible GI.

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