Novel In-Field Technique to Monitor and Optimize Asphaltene Inhibitor Performance: A Case Study from Gulf of Mexico
Authors: Punase Abhishek , Mazzeo Claudia , Garan Ron , Wylde Jonathan 
Published: September 2022

Asphaltene precipitation and deposition is a major flow assurance issue faced by the oil and gas industry. The complex nature and non-uniform molecular structure of asphaltenes complicates efforts to accurately assess their stability. Moreover, developing test methodologies with strong laboratory-to-field correlation presents additional challenges. The focus of this study is to discuss the successful validation and application of a novel test method for monitoring and optimizing the performance of an asphaltene inhibitor over incumbent product in a Gulf of Mexico deep-water field leading to approximately 40% reduction in operating dosage requirement.

Application of a newly developed asphaltene inhibitor was performed on a deep-water field in the Gulf of Mexico region experiencing severe asphaltene deposition problems. This study evaluates the correlation between the thermo-electric properties and dispersion tendencies of asphaltenes in treated (with incumbent and new inhibitors) and untreated crude oil samples at both laboratory and field environments. The switching of inhibitor was conducted through multi-step process involving a solvent flush followed by new AI injected through the umbilical tubing. The pre-treatment and solvent flushed flow-back samples were collected, and thermo-electric values were measured to establish the base condition. Performance monitoring of the new inhibitor at various AI dosages was carried out in the field over a duration of 3 months to validate the direct laboratory-to-field relationship.

Higher readings of the thermo-electric property are indicative of a better dispersion state of the polar asphaltene fraction within the test sample. Hence, the pre-treatment samples were observed to have lower thermo-electric values as compared to the flow-back samples collected after the solvent flush stage. Stabilized higher readings were recorded for the samples analyzed in the next three months and a step- down trend was observed with reduction in AI dosage to the lower optimized level. Add itionally, the amount of asphaltene that can be precipitated from the field samples were also measured and it followed an inverse relationship with the thermo-electric values, corroborating the expected asphaltene stability behavior. Furthermore, differential pressure across the flowline was also monitored for this well to confirm the absence of asphaltene deposition throughout the assessment period. A strong correlation between the laboratory and field results obtained from this thermo-electric technique and its validation with other industry standard methods highlight the reliability and high degree of accuracy of the novel method.

With this study, an innovative method of assessing and monitoring the stability of asphaltenes and efficiency of an AI within the native crude oil medium is presented. The effectiveness of the technique to decipher and record variations during different stages of an asphaltene remediation job demonstrates its robustness and applicability as an efficient monitoring tool with great laboratory-to-field correlation.