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→Decrease in relative permeability
Some oils can precipitate appreciable amounts of paraffin or asphaltenes as the temperature and pressure are reduced in the near wellbore region. Most often these deposits form near the surface where the temperature is lowest. However, there have been many confirmed cases of paraffin buildup near the perforations. Removal of these deposits can be accomplished with heated oil or chemical solvents.
Some oils can precipitate appreciable amounts of paraffin or asphaltenes as the temperature and pressure are reduced in the near wellbore region. Most often these deposits form near the surface where the temperature is lowest. However, there have been many confirmed cases of paraffin buildup near the perforations. Removal of these deposits can be accomplished with heated oil or chemical solvents.
===Decrease in [[relative permeability]]===
===Decrease in relative permeability===
As the well is produced, the lowest pressures are observed near the wellbore. In oil reservoirs, this pressure drop can result in the release of gas. Similarly, in a gas reservoir, the lower pressure can result in the formation of condensate fluids around the wellbore. The increase in saturation of a second phase of fluid decreases the permeability to flow of the primary fluid. The ability of these different fluids to flow is defined by the relative permeability characteristics of the rock and the fluids. To reduce this problem, a method must be implemented, such as hydraulic fracturing, to help decrease the pressure drop around the wellbore (see [[Stimulation]]). Eventually, pressure will deplete further out in the reservoir and the flow capacity of the primary fluid will be reduced.
As the well is produced, the lowest pressures are observed near the wellbore. In oil reservoirs, this pressure drop can result in the release of gas. Similarly, in a gas reservoir, the lower pressure can result in the formation of condensate fluids around the wellbore. The increase in saturation of a second phase of fluid decreases the permeability to flow of the primary fluid. The ability of these different fluids to flow is defined by the relative permeability characteristics of the rock and the fluids. To reduce this problem, a method must be implemented, such as hydraulic fracturing, to help decrease the pressure drop around the wellbore (see [[Stimulation]]). Eventually, pressure will deplete further out in the reservoir and the flow capacity of the primary fluid will be reduced.