Integrated Reservoir/Wellbore Production Model for Oil Field Asphaltene Deposition Management

Abstract

Asphaltene deposition prevention, mitigation, and management remains a major challenge to the oil industry due to its complexity and current poor understanding and inadequate predictive tools. A literature review study on the asphaltene deposition revealed a lack of integrative models that link reservoir, wellbore, and surface facility to predict asphaltene deposition and take into account their effect on each other. In addition, most of the existing studies are focused on the thermodynamics aspects of asphaltene precipitation, or single-phase asphaltene deposition modeling. Therefore, it is critical to model asphaltene deposition under multiphase flow conditions to, accurately, develop prevention, mitigation, and management strategies, which depends on not only asphaltene thermodynamics, but also multiphase flow hydrodynamics and behavior. The objective of this study is to develop a robust systematic approach for predicting asphaltene deposition in production system through coupled reservoir and wellbore production model, which provides a cost-effective optimal mitigation and management strategies. The proposed work in this study integrates five models, namely reservoir asphaltene deposition model, equation-of-state (EOS) model, asphaltene thermodynamics precipitation model, mechanistic multiphase flow model, and asphaltene deposition transport model. The above-mentioned models are integrated using developed workflow platform, which enables compositional tracking throughout the entire production system. Furthermore, experimental fluid characterization data was used to tune the EOS model and the thermodynamic asphaltene precipitation models to ensure accurate phase behavior and the volumetric calculations, as well as of asphaltene and resin precipitations at any operating conditions. A field case study is used to evaluate the proposed integrated model, which indicates severe asphaltene depositions in production tubing and flowline. The proposed model predicted the thickness growth with time of asphaltene deposits on the inner tubing wall. The model results also show that local asphaltene deposition reduced tubing cross-sectional area, increasing in-situ superficial oil and gas velocities, thus increasing pressure drop. These results are critical in selecting, optimizing, and implementing asphaltene deposition mitigation and management strategies, which impacts project economics.