Integrated reservoir/wellbore production model for oil field asphaltene deposition management

摘要

Asphaltene deposition prevention, mitigation, and management remains a major challenge to the oil industry due to its complexity, poor understanding, and inadequate predictive tools. A literature review study on asphaltene deposition revealed a lack of integrative models that link reservoir, wellbore, and surface facility to predict asphaltene deposition taking into account the effect of their interaction on asphaltene deposition. In addition, most of the existing studies are focused on either modeling the thermodynamics aspects of asphaltene precipitation, or single-phase asphaltene deposition. 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 coupling reservoir and wellbore production models, 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 to ensure accurate phase behavior and volumetric calculations, and to tune the thermodynamic asphaltene precipitation model. A field case input data is used to evaluate the proposed integrated model, which indicates severe asphaltene depositions in production tubing. The proposed model predicted the location and growth of asphaltene deposition thickness with time and space in the inner production-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 and decreasing flowrate. Sensitivity analyses to investigate several parameters such as depletion drive mechanism, asphaltene particle size, and injection of CO2 rich gas on asphaltene deposition show excellent results that are aligned with the physical and theoretical understanding of asphaltene deposition. These results are critical in selecting, optimizing, and implementing asphaltene deposition mitigation and management strategies, which affects project economics and safety.