How do you precipitate asphaltenes?
The two most prevalent causes of asphaltene precipitation in the reservoir are decreasing pressure and mixing of oil with injected solvent in improved oil recovery (IOR) processes. Drilling, completion, acid stimulation, and hydraulic fracturing activities can also induce precipitation in the near-wellbore region.
What are asphaltenes in crude oil?
Asphaltenes are the crude oil component with the highest molecular weight. They are conditionally defined as fractions insoluble in pentane or heptane; their presence in heavy oil provides its high viscosity. Therefore, the removal of asphaltene is one of the most efficient methods for the reduction of oil viscosity.
How do you remove asphaltenes?
Asphaltene deposits are generally removed manually, if present in readily accessible equipment, such as separators and other surface equipment. For tubular and flowline deposits, removal techniques involve chemical methods such as solvent soaks with or without dispersants.
What are Maltenes in asphalt?
Maltenes are the n-alkane (pentane or heptane)-soluble molecular components of asphalt, which is the residue remaining after petroleum refiners remove other useful derivatives such as gasoline and kerosene from crude oil. Asphaltene compounds are the other primary component of asphalt.
How are asphaltenes formed?
Asphaltene deposition can also be induced by changes in composition of the crude oil through injection of fluids such as CO2 or lean gas. Several studies have documented the possibility of asphaltene precipitation during lean gas and CO2 injection. Large changes in temperature can also induce asphaltene deposition.
What are asphaltenes made of?
Asphaltenes are the most abundant components of a crude oil mixture. Asphaltenes consist of polycyclic aromatic rings, an aliphatic chain, and various heteroatoms (oxygen, sulfur, or nitrogen). The combination of these three subcomponents defines the properties of the crude oil mixture.
Are asphaltenes polar or nonpolar?
Asphaltenes and resins are polar, while the rest of the so-called oils are either nonpolar or mildly polar. The interaction among these species strongly affect asphaltene precipitation from petroleum fluids.
What is asphaltenes in fuel?
Asphaltenes are formed when diesel fuel is heated under high pressure as it passes through today’s high pressure fuel injection systems. These systems operate at about 30,000 PSI (pounds per square inch) which is about six times the pressure of the previous conventional fuel injection systems.
Do Maltenes increase viscosity?
The correlation between softening point and maltene percentages. viscosity was markedly reduced by 15% maltene, bringing it close to the 650 mPa. s value of virgin bitumen viscosity, as reflected by viscosity at 135, 150 and 165°C.
What are the causes of Asphaltene Precipitation?
Asphaltene precipitation is caused by a number of factors including changes in pressure, temperature, and composition. The two most prevalent causes of asphaltene precipitation in the reservoir are decreasing pressure and mixing of oil with injected solvent in improved oil recovery (IOR) processes.
What is Asphaltene precipitate test?
The test is designed to measure the amount of asphaltene that will precipitate when an oil sample is diluted with various ratios of n-alkene agent, n-pentane, and n-heptane. Essentially, the test is conducted by placing a known quantity of the reservoir oil in a special PVT cell and allowing it to reach reservoir temperature.
Does the amount of heptane affect the onset of Asphaltene Precipitation?
This onset of asphaltene precipitation as a function of the amount of heptane in the test liquid was determined for 20 and 50 vol% of oil in the oil and test liquid solution. HD was measured directly through heptane dilution tests that quantify the maximum amount of heptane, VH, which can be added to the crude oil without precipitating asphaltenes.
How do you measure Asphaltene Precipitation in oil?
Acoustic data exhibit sharp changes at pAu and at the oil saturation pressure, ps . Light-scattering techniques also have been successfully used to measure the APE. For dark-colored oil, a near-infrared laser light system (800×10 -9 m to 2200×10 -9 m wavelength) is required to detect asphaltene-precipitation conditions.