Modeling the Effect of Asphaltene on the Development of the Marrat Field

Abstract

Abstract This paper describes the study of the effect of asphaltene precipitation and deposition on the development of the Marrat field using a compositional simulation model with asphaltene modeling facilities. The model enables the simulation of asphaltene precipitation, flocculation, and deposition including adsorption, plugging, and entrainment, and the resulting reduction in porosity and permeability and changes in oil viscosity and rock wettability. A workflow was established in the study to i) characterize the equation of state (EOS) by analyzing the fluid PVT and asphaltene data from the lab; ii) calibrate the asphaltene model input parameters using the core flood experimental data; and iii) incorporate the EOS and the asphaltene parameters into the full field simulation model. The model was used to analyze the effects of asphaltene on various development scenarios, including depletion and water injection. For each scenario, the following were calculated and analyzed: field performance including production of oil, gas, and water; asphaltene behavior including precipitation, flocculation, adsorption, plugging and entrainment; formation damage and the effect of rock wettablity changes. The results show that the formation could be severely damaged near the producers where asphaltene is more likely to precipitate because of lower pressures (below the asphaltene onset pressure) and longer time exposure to a larger amount of oil. Formation damage could be reduced by flushing away the deposited asphaltene using higher flow rates if plugging is not significant. The water injection scenario with higher injection rate and higher production rate with BHP limit above 6,000 psia results in less asphaltene adsorption, more entrainment, and therefore less deposition. This in turn causes less permeability damage and more oil production.