A Simplified Method to Predict and Prevent Asphaltene Deposition in Oilwell Tubings: Field Case

摘要

The natural state of asphaltene in petroleum fluids is describedas a colloidal system stabilized to some extent by the resinsthat act as peptizing agents. Destabilization of colloidalasphaltene appears to happen as a result of changes intemperature, pressure, and composition. This can significantlyaffect the production efficiency of the reservoir duringoil recovery.The phenomena of asphaltene flocculation and depositionin oil well tubing appear to be influenced by two mechanisms,the fluid phase (gas/liquid/solid) separation and well flowregime respectively. The predictions of the onset of asphalteneflocculation determined by fluid phase laboratory studies donot necessarily imply that asphaltene deposition will occurduring flow conditions. We believe that the deposition is dueto the change in well flow regimes under the effect ofreservoir drawdown pressure. This paper presents a methodcapable of predicting the onset of asphaltene deposition underwell flow conditions. This allows us to take preventive actionsbefore asphaltene problems occur by keeping the asphaltenedispersed in the oil phase.A well monitoring technique was conducted in WestKuwait Marrat (Jurassic) deep wells to monitor the behaviorof the well flowing pressure using programmable data logger.The data gathered from the logger have predicted the onset ofthe mechanism that influenced asphaltene deposition in welltubing. The deposition thickness of asphaltene in well tubingwas estimated by the data and was found agreeable with theresults obtained by the caliper test.