Practical Prediction of Asphaltene Mitigation Based on Dynamic Asphaltene Inhibitor Test DAIT

Abstract

Abstract Asphaltenes in the production process often cause significant damage to oil production operation through the continuous growth process (precipitation followed by aggregation and finally deposition) of their particles. To mitigate the asphaltene-induced problems, Asphaltene Inhibitor is used to control precipitation and/or deposition of asphaltene particles. In addition to the typical ambient-conditioned Asphaltene Inhibitor-evaluation known as Asphaltene Dispersancy Test, this study applied the Dynamic Asphaltene Inhibitor Test to select candidate Asphaltene Inhibitors at operating conditions. The Dynamic Asphaltene Inhibitor Test used a simple dynamic flow equipment consisting of capillary coil and filter to detect asphaltene precipitation and deposition independently. Based on Asphaltene Inhibitors experimentally screened through a series of Dynamic Asphaltene Inhibitor Test, four Asphaltene Inhibitor numerical models were reproduced to assess how Asphaltene Inhibitors mitigating asphaltene risks. A numerical model assuming no Asphaltene Inhibitor was built as reference by calibrating with conventional Pressure Volume Temperature (PVT) experimental results and asphaltene onset pressure. Asphaltene Inhibitor models were generated from the reference model on the basis of comprehensively interpreted data containing available Asphaltene Inhibitor characteristic information. In the Asphaltene Inhibitor models, pseudo heavy components of the crude oil used in Dynamic Asphaltene Inhibitor Test were characterized with cubic-plus-association equation of state. The Asphaltene Inhibitor models were validated by comparing with the relative Asphaltene Inhibitor's effectiveness in experimental evaluation. To understand transition from Asphaltene Precipitation Envelopes to Asphaltene Deposition Envelope, the findings of deposition-information from the Dynamic Asphaltene Inhibitor Test were incorporated into the Asphaltene Inhibitor models. To be more specific, the deposition behavior was estimated on thermodynamic plot by assuming the Dynamic Asphaltene Inhibitor Test condition as pseudo onset condition. The Asphaltene Precipitation Envelopes on thermodynamic plots revealed causing asphaltene precipitation possibly in part of the operation conditions even using Asphaltene Inhibitor. On the other hand, Asphaltene Deposition Envelope suggested that Asphaltene Inhibitor application could reduce asphaltene deposition over a wide range of the operation condition. The upper-boundary locations of Asphaltene Precipitation Envelopes and Asphaltene Deposition Envelope were apart from each other. The fact revealed that Asphaltene Inhibitor could delay asphaltene aggregation and deposition after precipitation. This paper describes a more realistic Asphaltene Inhibitor modeling method based on the Dynamic Asphaltene Inhibitor Test measurement results.