Characterization and Modelling of Asphaltene Precipitation and Deposition in a Compositional Reservoir

Abstract

Abstract This paper presents results of phase behavior calculations and simulation of asphaltene precipitation and deposition in The Carito-Mulata Field, based on a reliable experimental support. The Carito-Mulata Field is a complex compositional system which changes from gas condensate at the top to an under saturated black oil in the flank. In this area Asphaltene precipitation becomes a serious problem where plugging of the formation, wellbore and production facilities dramatically affect the productivity and final recovery of the area. To help to prevent the asphaltene precipitation a high pressure maintenance project has been applied by gas and water injection. Therefore it has been considered mandatory to define a representative numerical model to predict the phase behavior of asphaltene precipitation and deposition. As first part of this study a complete experimental plan was carried out involving several PVT analyses, measurements of precipitation onset pressures and plugging core analyses. PVT analysis was used to match a Peng-Robinson EOS in order to reproduce the phase behavior of the system. Asphaltene precipitation as function of pressure was modeled by a pure solid model which was matched by measurements of precipitation onset pressures. A Solid deposition model was matched based on core analysis to reproduce the reduction of porosity and permeability by asphaltene deposition. At the end, a simulation study based on a radial single-well and a 3D model was carried out to validate the predicting model and analyze the Impact of the asphaltene deposition in the well productivity and how it affects the efficiency of different production strategies. It was compared to the impact in the design of production plans taking into consideration the asphaltene modelling and not taking this into consideration. Also it showed how the reported observations in the field, in Lab and in the literature were adequately reproduced.