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

Abstract

Summary The natural state of asphaltenes in petroleum fluids is described as a colloidal system stabilized, to some extent, by the resins that act as peptizing agents. Destabilization of colloidal asphaltenes appears to happen as a result of changes in temperature, pressure, and composition. This can significantly affect the production efficiency of a reservoir during oil recovery. The phenomenon of asphaltene flocculation and deposition in well tubing appears to be influenced by two mechanisms: the fluid-phase (gas/liquid/solid) separation and the well-flow regime. Predictions of the onset of asphaltene flocculation determined by fluid-phase laboratory studies do not necessarily imply that asphaltene deposition will occur during flow conditions. This paper presents a method for predicting the onset of asphaltene deposition under well-flow conditions. This method will allow us to take preventive actions before asphaltenes problems occur by keeping the asphaltenes dispersed in the oil phase. A well-monitoring technique was used in west Kuwait Marrat (Jurassic) deep wells to monitor the well-flow pressure by use of a programmable data logger. The data gathered from the logger predicted the onset of the flow-regime mechanism that influenced asphaltene deposition in well tubing. The deposition thickness of asphaltenes in well tubing was estimated by the data and was found to agree with the results obtained by the caliper test.