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GROUP MEMBERSGROUP #1:AHMED HUSSIEN ABD EL AZIZESLAM YAKAN MOURADAHMED SAEEDAHMED GAMALABD EL RAHMAN EL HADYABD EL HAMED ABDO MOHAMEDAHMED EL ATTARGROUP #6:MOHAMED ABD EL MONEM SAEEDDOAA ABD EL WAHABAYMAN DOSOKY HUSSIENMAHMOUD GHONEM HASSANMOHAMED ABD EL MONEM MOSELHYSHAABAN MOHAMED SALEMAgendaINTRODUCTIONOCCURRENCE & CONDITIONSFACTORS AFFECTING Asphaltene SOLUBILITYPREDICTION METHODSMODELING THE ASPHALTENE DEPOSITESMITIGATION METHODSCONCLUSIONSREFRENCES INTRODUCTIONDefinitions:High molecular weight aromatic-organic substanceThe heaviest fraction in M.wt. and aromaticityCarry intrinsic charge (- /+)Asphalt refers to combination of asphaltenes and resinsINTRODUCTIONProperties:Asphaltene M.wt. ranges from 1000 : 100,000Micro-particle density 1.2 g/ccRemain in solution or colloidal suspension at Pres&TresPrecipitated when stability disrupted

OCCURRENCE & CONDITIONSDestabilization of asphaltenes stability occurs when removes the resin protective layer might lead to flocculation and precipitation of asphaltenes.

OCCURRENCE & CONDITIONSAsphaltenes deposits can occur in: Near wellbore and perforationPiping system and facilitiesInto reservoir while different recovery methods or stimulation processFACTORS AFFECTING Asphaltene SOLUBILITYCrude oil composition:Asphaltene solubility is higher when the crude is heavier and more aromaticPressure effect:By decreasing the pressure, the relative volume fraction of the light components within the crude oil increases.Below the bubble point, asphaltenes are more soluble again due to evaporation of light crude oil componentsTemperature effect:Temperature has a less pronounced effect on aggregationincrease in temperature generally affects the aggregation of asphaltenes by decreasing the solvating power of the crude oilPREDICTION METHODSFluid Compositional CharacterizationResiduum FormationComposition of AsphalteneSARA(Saturate Aromatic Resin Asphaltene)Pressure DepletionExperimental MeasurementsIsothermal Depressurization TechniquesHigh-Pressure Microscopy (HPM)High-Temperature and High-Pressure FiltrationPREDICTION METHODSFluid Compositional Characterization

Residuum Formation: treatment of the residuum with liquid propane with temperatures not exceed 70oF precipitates the resins and asphaltenesPREDICTION METHODSFluid Compositional CharacterizationComposition of Asphaltene

PREDICTION METHODSFluid Compositional CharacterizationSARA(Saturate Aromatic Resin Asphaltene)

PREDICTION METHODSFluid Compositional Characterization

Pressure Depletion: Asphaltenes are known to aggregate by pressure depletion.EXPERIMENTAL MEASURMENTSSchematic representation of the thermodynamic conditions of the flow assurance elements:

MODELING THE ASPHALTENE DEPOSITESTwo approaches are used for modeling asphaltene precipitation:The asphaltene precipitation process is thermodynamically reversible.Asphaltenes are solid particles colloidally suspended in crude oil, which are stabilized by adsorbed resin molecules.MODELING THE ASPHALTENE DEPOSITESNghiem et al. (1993 and 1997) proposed a thermodynamic model that is capable of describing the asphaltene precipitation behavior over a wide range of pressure, temperature, and composition conditions.The model is based on treating the asphaltene as a pure solid phase while the gas and oil are modeled with a cubic equation of stateMODELING THE ASPHALTENE DEPOSITESMODELING THE ASPHALTENE DEPOSITESMODELING THE ASPHALTENE DEPOSITESThe vapor and liquid phases are described by an EOS, such as the Peng-Robinson EOS, with the Peneloux volume shift parameter.The modified fugacity of component i in the vapor phase, fVi , and liquid phase, f Li , is given by:

MODELING THE ASPHALTENE DEPOSITES

Equation is in a generalized form of the asphaltene fugacity that can be used to study the effect of pressure and temperature on asphaltene precipitation.MODELING THE ASPHALTENE DEPOSITESTHE F-H Model:A model has been used to describe the asphaltene precipitation mechanism by a polymeric solution theory. In this case, large asphaltene molecules are supposed to be similar in their structures and behaviors to polymer molecules and the deasphalted oil acts as a solvent.MODELING THE ASPHALTENE DEPOSITESAs the asphaltene is supposed to be a polymeric like substance dissolved in crude oil, the polymeric solution theory was used for the prediction of asphaltene precipitation in crude oil.

The solubility parameter

MODELING THE ASPHALTENE DEPOSITESThe amount of asphaltene precipitation in an oil sample has been calculated at different proportions of n-Heptane, n-Hexane, and n-Pentane precipitants based on the F-H model and the modified F-H model.The SRK EOS and the sample mixing roles have been used for calculation of the solubility parameter and the molar volume.MITIGATION METHODSChemical TechniquesMechanical TechniquesThermal Treatment TechniquesChemical TechniquesDispersants: work by surrounding the asphaltene molecules similar to the natural resin materialsAntifoulant: to inhibit the attachment and growth of deposits on surfaces and wallsAromatic solvents(e.g. toluene and xylene): to re-dissolve the asphaltene depositsE.g. Tarchek, Paragon, PAD, Parasperse.Chemical Techniques

1St step, entails cleaning out and flowing back the well, then pumping in activator and an oil spacer. The activator binds to the formation enhancing absorption of the inhibitor without changing formation wettability.

2nd step, the precipitation-inhibitor chemical is injected

3rd step, comprises a postflush with crude oil,

Final step, the well is shut in for 12 to 24 hours, giving the activator and inhibitor time to form a complex before production begins. one example from eastern Venezuela, severe asphaltene-deposition problems caused a high-volume production well to plug within seven months of treatment. 37 Several cleaning methods had been attempted, including physically scraping the wellbore and injecting xylene down the tubing. Each cleaning event cost approximately US $50,000 and two days of shut-in production. After squeeze treatment with activator and inhibitor, the oil production rate increased and the frequency of well cleaning decreased to every eight months. The combination of increased production and less frequent cleaning generated an annualized gain of 60,882 barrels [9,674 m3 ], and a return on investment of more than 3,000%.

26Mechanical TechniquesCoiled tubing: enter the pipeline and used to inject asphaltene solvents/inhibitorsDual Completion: with the purpose of: Using the second tubing string for solvent Access for lowering production testing devicesWirelinecutting: can be used to remove asphaltene solids inside the wellbore, provided the wellbore can be easily accessed.Pigging: used to remove asphaltenes inside manifolds and pipelines.Mechanical TechniquesPigging:effective for cleaning the tubing and linesCompared to wax, asphaltenes are brittle and hard, thus special pigs are requiredPigs with disks and cups should be usedpigging operations often require production shutdown

Disc & Cup PigFoam Pig

28Thermal Treatment TechniquesRemoval of deposits by hot fluidworks by melting the organic depositsInsure that the melted organics are not re-deposited, That is when:the hot fluid introduced to the formation becomes saturated with melted paraffinthe formation temperature is lower than the cloud point of the hot fluid.ConclusionsAsphaltenes are best knows for the problems they cause as solid deposits that obstruct flow in the production system.EOS provides models to predict conditions of Asphaltene presentations.Asphaltenes can be mitigated chemically, mechanically, and thermally.REFERENCES Ahmed, Tarek H. Equations of state and PVT analysis: applications for improved reservoir modeling, Gulf Publishing Co.,2007Boyun Guo, Shanhong Song, Ali Ghalambor, Tian Lin. 2014. Offshore Pipelines Design, Installation, and Maintenance. Chapter 15 Flow Assurance: Asphaltene Prevention and Remediation: 207-208.Akbarzadeh K., Hammami A., Kharrat A., Zhang A. 2007. AsphaltenesProblematic but Rich in Potential, Oileld Review: 39-41.G.Ali Mansoori. 2010. Remediation of Asphaltene and other Heavy Organic Deposits in Oil Wells and in Pipelines: 12-23.